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An Effective 2040m CW Transceiver - DOC - DOC

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					A Homebrew 20/40m Binaural CW Transceiver

Hannes Coetzee, B. Eng (Electron), ZS6BZP and Christo Pelster, M.Eng (Electron), ZS6AHQ

A binaural CW transceiver covering the 20 and 40m amateur bands is presented. (40m is
ideal for country wide contacts and 20m offers the opportunity for DX contacts.) Power levels
of 10W on 40m and 5W on 20m ensure reliable contacts with reasonable power drain if
battery operation is required. The design has been optimised for reproducibility by relatively
inexperienced persons having only access to the minimum amount of test instruments (if they
are comfortable working with SMD components). The result is ideally suited as a club project
or for hams wishing to construct their own gear for “Summits-on-the-Air” (SOTA) activities.


Introduction

When the achievable performance of the various receiver architectures is compared to the
complexity, cost and availability of components and reproducibility, few can beat the Direct
Receiver (DC) configuration. But unfortunately the basic DC receiver is not without its
drawbacks and shortcomings.

The major drawback of a DC receiver is the lack of image suppression. It is very apparent in a
busy band with closely spaced CW signals. Despite this the DC receiver is very popular for
homebrewing and low power, portable equipment. This may be an indication that the image
problem is not as serious as what may be thought at first and that it may be possible to enjoy
amateur radio to the fullest despite this inherent drawback.

It was decided to make use of a Binaural DC [1] receiver design to help overcome some of
the drawbacks. The design can also form the basis for a full featured, phasing method
Single-Side band transceiver.


Basic DC Receiver

A local oscillator (LO) signal, operating very close to the received frequency, is mixed with the
received signal. The result of this mixing process is two frequencies, the sum component at
double the operating frequency, and the difference component at audio or base-band. The
difference (audio) component is filtered out (selected) and amplified to a suitable level.




                             Direct   Conversion Receiver


                   Antenna       NE/SA602 TL071            LM386



                       Mixer/                Pre-           Audio
                       Oscillator           Amplifier      Amplifier


                           Figure 1. Basic Direct Conversion Receiver

Binaural I-Q DC Receiver

In the Binaural I-Q DC receiver the process is taken one step further: The incoming signal is
first divided into two paths, each feeding a mixer. A local oscillator (LO) signal, operating very
close to the received frequency, is also divided into two paths, but with a 90º-phase difference
between the two LO signals. The two LO signals are mixed with the two received signals.
Once again the difference (audio) components are filtered out (selected) and amplified to
suitable levels. The outputs are fed to a stereo headphone or two loudspeakers.




                                                                                               Pre-                 Audio
                      Antenna                              Mixer
                                                                                              Amplifier            Amplifier




                                  0                                              Oscillator

                      Power                                       90
                      Splitter


                                                           Mixer                                Pre-                     Audio
                                                                                               Amplifier                Amplifier


                                                         Figure 2. Basic Binaural I-Q DC Receiver

The 90º-phase difference between the two signals allows the human mind to create a virtual
stage of signals. The mind now not only classifies signals in terms of frequency, but also in
terms of position. It is now much easier to focus on individual CW signals, especially in a
crowded band. This helps to overcome the inherent drawback of the basic DC receiver.

Implementation
The basic Binaural DC RX design is now extended to provide solid performance on the
sometimes-challenging 20 and 40m amateur bands.

  SOTA 20/40m CW Binaural Transceiver                                                                                                NE602
  by ZS6BZP and ZS6AHQ                                                                                                    7/14MHz
                                                                                                                                                    TL072                          Audio
                                                                                                                                                                                   Amp
                                                                                                                                                    Pre-
                                                                                                                                                                                   LM386
                                                                                                                                                    Amp
                                                                                                                                 NE602                           Vol
                                         20m                                            20m            Rx
                                                                 HPF                                                                                                        Side           OR
                                                                                                                                                    TL072
                                                                                                                                                                            Tone
              HPF                                       13.6 MHz                                                                                    Pre-
                            LPF                                                                                                                                                    LM386
                                                           HPF                                                                                      Amp
                                                                                                                                                                Vol
       6.8MHz HPF          14.5MHz                         LPF                         40m             Tx                                                                           Audio
                                         40m
                             LPF                                                                                                                                                    Amp
                                                                                                   Push-Pull                        0º      90º
                                                         7.5 MHz                                   MOSFET
                                                           LPF                                                                                          Side Tone
                                                                                                    Power                            4                                            CW key
                                                                                                   Amplifier                                             (NE555)
                                                                                                                                 (74AHC04)
                                                                                                                          180º
              Encoder
                                                LCD_LOAD                                                                                          74AHC251
                                     PIC16F84




                                                                       AY-0438




                                                                                                            4½ Digit                                 20m/40m
                                                                                 LCD Driver




                                                                                                                                                               20m
                                                                                 32 segment




                                                LCD_DATA                                                                                                              40m
                                                LCD_CLK
                                                                                                             LCD
                                        A




                    STEP
                                                                                              32                                                 28-
                                                      DDS_CLOC
                                            DDS_DAT




                    Tx/R
                                            DS_FSYN




 Rx     Tx                                                                                                                                    28.7MHz
                    x
 20m                BAN                                                                                                                      2
        40m
                    D                                                                                                                    (74AHC04)                         +T
                                                      A
                                                      K
                                            C




                                                                                                                                                                            x        CW
                             X-Tal •                                                                      x3               x3
                                                                                                                                                               +R      Tx/Rx         Key
                            Ref Osc
                                           AD983                                 LPF                                                                            x      Control
                                                                                                      (74AHC04)        (74AHC04)       56-
                            50MHz            5                                                                                      57.4MHz
                                              DDS
                                             6.222-                         6.8MHz
                                           6.377MHz

                           Figure 3. SOTA 20/40m CW Binaural Transceiver Block diagram
Input/Output Filter

A selectable band pass filter is required at the input of the receiver to ensure that the receiver
only responds to the signals of interest. But band pass filters normally require alignment,
which implies that some additional test equipment may be required. This is in contrast to the
design goals of simplicity and reproducibility. The solution is to use separate high pass and
low pass filters.

A 6.8 MHz, fifth order Chebyshev high pass filter with 0.5 dB ripple and a 14.5 MHz, fifth order
low pass filter are permanently in the signal path. When operation on 40m is required, an
additional 7.5 MHz low pass filter is switched in the signal path. For operation on 20m, a 13.6
MHz, fifth order Chebyshev high pass filter with 0.5 dB ripple is switched in the signal path.
The wider-than-absolutely required filter bandwidths ensure reproduce-ability while still
protecting the receiver from strong, out-of-band signals.

The same filter combinations are used in the transmit path. Very high voltages exist on a
band pass filter with the planned 10-Watt power level. Once again this will require special
components, but the separate high-low pass filter combination ensures a clean output signal.

Use is made of IM-5 moulded inductors. The Q values of moulded or bought-out inductors are
adequate for the required power level and the requirements of low or high pass filter
arrangements.

Capacitors are low cost ceramic units with a zero temperature coefficient (NP0). 100V ratings
are once again adequate for the required power levels.

A 100 kΩ, 1-Watt resistor at the antenna terminal bleeds any static build-up to ground. This
helps to protect the transceiver against electro-static-discharge (ESD) damage without
influencing the functioning of the TRX.
Mixers

Deciding on the specific mixer to implement was a difficult decision as so many options were
available. Suitable candidates include a selection of passive, double balanced mixers from
Mini-Circuits, active mixers from Analog Devices and a balanced mixer using CMOS IC‟s
developed by one the authors [2,3].

The ease of implementation, low noise figure and medium gain eventually swung the decision
in favour of the NE602 family, an old favourite among radio amateurs.

Balanced inputs and outputs are required to get the „602 to perform at its best. On the input
side this is easily implemented with a RF transformer wound on a balun core. Impedance
matching from the filter‟s 50 Ω to the high impedance of the „602 is also implemented on the
same RF transformer.

Power dividing of the received signal are accomplished by paralleling the inputs of the two
„602‟s, no need for exotic power dividers here.


Audio Buffers

The balanced outputs of the „602 are converted to a single ended audio signal with the aid of
a low cost, low noise op-amp implemented in a differential amplifier configuration.

The 1.5 kΩ impedance of each of the „602‟s outputs defines the gain of the audio stage in
conjunction with the 22 kΩ feedback resistors. A simple audio high pass filter with a corner
frequency of 300 Hz is implemented with the aid of the 330 nF DC blocking capacitors. 4.7 nF
capacitors across the feedback resistors help to limit the audio bandwidth. Higher value
capacitors can reduce the bandwidth even more, but the audio quality may suffer when
monitoring SSB signals.

A 100 nF capacitor across the inputs of the differential amplifier prevents brake through of
very strong commercial AM broadcasts.


Audio Amplifiers

A stereo 10 kΩ potentiometer does duty as a volume control. The audio signals are fed to
another two Old Faithfuls: LM386 audio power amplifiers. There is nothing special about the
implementation. The 10 Ω, 10 nF combination at the output ensures that the amplifier is
properly terminated at high frequencies and prevent RF from braking through on the audio.
An R-C feedback network between the output (pin5) and pin 8 reduces the bandwidth of the
LM386 and saves the ears from the notorious high frequency hiss generated by the LM386.
The side tone signals are fed via another 10 kΩ potentiometer to the normally grounded input.

The output level of the „386 is adequate to drive a small 8 Ω loudspeaker to comfortable
levels or earphones to ear-splitting levels. The outputs of the two „386‟s drive two small
loudspeakers mounted on either side of the enclosure to give the binaural advantage even
when earphones are not used.


VFO

Generating a clean, stable, adjustable local oscillator and displaying the operating frequency
can be much more complex than the transmitter and receiver circuitry. Once again many
options were investigated, ranging from free-running VFO‟s with variable capacitors to exotic
Phase-Locked-Loops under microprocessor control.
The simplest solution seemed to be a dedicated voltage controlled oscillator, the LTC1799.
On paper it seemed a viable option, but measurements done on a sample highlighted the
shortcomings of this device very clearly. The stability, phase noise and “purity of note” are
simply not good enough for communications purposes.

Generating the two LO signals with the required 90º-phase difference at the operating
frequencies of 7 and 14 MHz are done with the aid of dual flip-flop logic gates (SN74AHC74)
clocked at four times the operating frequency. The quadrature outputs of the flip-flops are
terminated in two resistor divider networks that ensure a modest load current of 5 mA / gate
and the correct drive levels for the mixers [4]. The LO frequency required for operation at
14.350 MHz is thus 57.4 MHz. Free-running oscillators operating at such a high frequency
tends to be very unstable, or other techniques require lots of complicated circuitry.

It was decided to use a low frequency LO operating at between 6.2 and 6.4 MHz followed by
two frequency triplers (x9) to generate the required clock signal to feed the quadrature
generator (dual flip-flops). Operation on 7 MHz requires an additional divider, implemented
with a flip-flop, ensuring easing band selection with the aid of a 74AHC251 multiplexer.

The two, frequency triplers are implemented with a single CMOS hex buffer (SN74AHC04).
The output of the VFO is squared before driving the first tripler. A square wave can be
considered as the fundamental (sine wave) and a large amount of odd harmonics added
together. The fundamental is suppressed by a tuned circuit formed by a capacitor and
inductor. The third harmonic is selected by the tuned circuit formed by the same inductor and
the other capacitor. The output signal is once again squared by one of the CMOS inverters
and the process repeated for the next tripling action. [5]

A low cost Direct Digital Synthesiser (DDS) controlled by a PIC processor is probably the
simplest way to generate a very clean and stable LO signal. The PIC can then also display
the frequency on a low cost, 4½-digit Liquid Crystal Display. The readability of these displays
is better than the 2 x 16 types. A low cost rotary encoder is used for frequency adjustment
purposes.
                   TM
An Analog Devices AD9835 complete DDS is well suited for the requirements. Most
modern DDS‟s generates a very clean output if the clock frequency is at least eight times
higher than the output frequency. 50 MHz clock oscillators are common and relatively low
cost. An Elliptical low pass filter using standard, off-the-shelf components follows the output of
the DDS. This ensures a spectrally clean signal to drive the frequency tripler chain.

The output frequency of the VFO is shifted (lowered) by eight hundred Hertz during
transmission to ensure that the transmitted signal is on the same frequency as the received
signal.


DDS
           TM                                       TM
A PICMicro 16F84A manufactured by Microchip is used to calculate and send the
programming commands to the DDS. This microprocessor is also used to display the
frequency and handle other functions such as frequency adjustments from the rotary encoder,
band select, tuning step changes and transmitter-receiver offsets. The internal RC oscillator is
used reduce component count.
                                                                               TM
The 32-segment display driver (AY-0438) is also manufactured by Microchip

The DDS uses a 50 or a 40 MHz crystal oscillator as a reference. The output of the DDS is
calculated based on this reference frequency and the programming word in the following
relationship:

Fout = (Fclk x Freg)/2^32                                                            [1]
The DDS frequency for 20m must therefore be 4/9 of the displayed frequency and 8/9 of the
displayed frequency for 40m.

The PIC has a few tasks that it needs to perform, almost at the same time, but independent of
each other (not strictly multi-tasking):

    1. Check Band Selection switch
    2. Check Tx/Rx mode
    3. Check Step Change input
    4. Check for changes in the Shaft Encoder (increment or decrement)
    5. Check frequency limits
    6. Calculate the Digits to be displayed and send them to the display
    7. Calculate the DDS word and send them to the DDS chip


The DDS word is only calculated and sent to the DDS chip when the frequency has changed
(including band change) and when the Tx/Rx mode changed. When no user input is active,
the DDS retains the previous generated frequency. This avoids additional output spurious
signals.

The frequency limits for the 20m and 40m band are set in the PIC code to ensure no out-of-
band transmissions are possible. The display flashes to indicate when the lower or higher limit
was reached.


Side tone Oscillator

Another Old Faithful is called up for duty as the side tone oscillator. The 555 is probably the
world‟s most versatile IC. A low power, CMOS version (7555) is preferred for this application,
but any version will function in the circuit. The output is fed via a simple, low-pass filter to the
audio amplifiers. The levels are adjustable via the pre-set potentiometers.

A side tone is generated whenever the key is pressed, independent of the radio been in
transmit mode or not. The side tone generator serves double duty as a test oscillator for
debugging the audio stages and as a CW practise aid.


RF Power Amplifier

Two square wave signals with a 180º phase difference are available from the flip-flops. The
frequency of these signals is either at 7 or 14 MHz, depending on the selected band. Hex
inverting gates (SN74AHC04) are used to buffer these signals. The remaining inverting gates
are paralleled to drive a pair of power FETs normally used in switched mode power supply
applications. The push-pull output signal is transformer coupled via a balun core to the
applicable output band pass filter.

Power to the FETs is supplied via a centre tap on the transformer. The balanced configuration
prevents DC saturation of the transformer core. The driver inverting gates are only powered
during the transmit cycle. The 74AHC04‟s are run from a 6V supply to ensure that the power
FET‟s are properly switched on. This voltage is slightly higher than normal, but still with-in the
manufacturers absolute maximum rating of 7V. Gate resistors ensure that the power FETs
are totally switched off during reception.

The diodes that are built into the FETs provide reverse polarity protection in case the supply
to the Transceiver is accidentally connected the wrong way round.
Availability of Components

It may be difficult to obtain some of the components in low quantities. Agents for all the
components can be found on the Internet and they will be more than willing to supply larger
quantities for example for a club project.


Construction

This transceiver is definitely not a beginner‟s project. This is not due to the complexity, but
rather because many of the components used are only available as surface mounted devices
(SMD). A double sided, through plated PC board considerably eases the construction of the
transceiver. The PC board is a standard Euro card (100 x 160 mm) size. The microprocessor
and DDS portion is cut off to enable it to be mounted on the front panel of a suitable
enclosure.

It is recommended that the output audio stages are built and tested first. After this is done
connect loudspeakers and a suitable power supply. Touching the inputs of the amplifiers will
result in a loud hum or noise, indicating that there is a good chance that the output stage is
functioning correctly.

Next step is the completion of the sidetone oscillator. Shorting of the “key” connections must
result in an approximately 800 Hz tone on the loudspeakers.

It is now the time to get brave and take on the mixed technology (leaded and SMD)
microprocessor and DDS board. This board can easily be tested on its own once completed.

The rest of the transceiver can now be completed with the experience gained working with
SMD.


Operation

Operation is very simple with the lack of bells-and-whistles. The transmitting frequency is 800
Hz lower than the received frequency. It is easiest to start at the low frequency side and tune
through a signal until it becomes audible in the left ear. This ensures that the correct side
band is selected and that the transmitted frequency is nearly zero-beat with the station that
you want to contact.

The binaural effect is also very apparent as the CW signal “moves” from in front of you in an
elliptical fashion to the right, again in front of you and then slightly to the left as the received
frequency is increased. It is a very unique and enlightening experience on a crowded CW
band.

The step size is changed by pressing the STEP button. The default step size is 10 Hz, which
is useful for CW tuning, while the coarsest step size is 1 kHz. The step size cycles through 10
100  1000  1 Hz. It is easiest to search for activity with the bigger step increments and
then use the small increments for fine-tuning.

The receiver unfortunately suffers from a few spurious responses. These are probably caused
by the clock signals of the DDS and the PIC as well as the multiplication and divider circuits.
The receiver was found to be more than useful despite this.


Summary

An effective, dual band, binaural CW transceiver was described. One of the main drawbacks
of a direct conversion receiver (lack of image suppression) is turned into an operator aid with
the implementation of the binaural I-Q principle.
To reduce the component count and enhance repeatability, “luxuries” such as an AGC and an
S-meter is omitted. The design focussed on solid RF performance with readily available
components. The transceiver is ideally suited as a club project or for personal construction, as
long as the constructor has experience with surface mounted components.


References

1. A Binaural I-Q Receiver. Rick Campbell, KK7B. The ARRL Handbook for Radio Amateurs
   2002. pp 17.70 – 17.75

2. A Low-Cost, High Performance Mixer for HF Applications. P J Coetzee, Engineer‟s
   Notebook, RF-Design, June 1995

3. Multi-band, direct conversion receiver. Hannes Coetzee, ZS6BZP. Electronics World,
   February 1998. pp138-143

4. Circuits, Systems & Standards. Edited by Ian Hickman. Electronics World + Wireless
   World. November 1991. pp 939 – 943

5. CMOS Frequency Multiplier. Gert Baars. Elektor Electronics. 7-8/2004. pp 34 – 35
                                                                                                                                                           20m
                                                                                                                                                                   COM
                                                                                                                                                                            40m




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P1                270pF                180pF                   270pF                     L3                              L4                                                                                470pF                            820pF 470pF                                    C12                                               C13                                                    100nF                                              16V                        10uF
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              100K                 L5        L6                270pF                          470pF                           270pF                                                                                                                                                        C20          2                                                        C18                  -             TL072                                                    7       +              5                 1           2
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                                         5      6                                R9                                                                        N30                                                                                                                             C34                                               C35             4n7F          22K                      100nF                                              16V                        10uF                                                  3
                                                                                                                                                                                                                                                                                                                                                                                      8




                                                                                 10K                                                                                                             R10                               C33                                                     10nF                                              330nF                                                                                                                            1             2         R6
                                                                                                                                                                                                                                                                                                                                                         1



                                                                                                                                                                                                                                                                                                                                                                    2




                                             IC4E                                                                                                                                            2                 1               1                 2                                    1           2         IC5                          1           2                           5                  IC1B                                                                                              10K
                                                                                                                                                                                                                                                                                                                                                                                                                  1




                                                                                                                                                                                                                                                                                                                                                                                      +
                                                                                                                                                                                                                                                                                                                                                                                                                                                                     6
                                                                                                                                                                                                                                                                                                                                                                                                                                                                     1




                                             74AHC04                                                                          T2                                                                                                                                                                        1                        4                                                                    7                                                                             16V                 C37                                  Earphone
                                                                             2




                                                                                                                                                                                                                   1




                                                                                                                                                                                                                                                                                                                                                         2




                                                                                                                                                                                                                                                                                                                                                                                                                                            1




                                        11        10                                                                 6             1                                                                 1K                            10nF                                                                      IN1    OUTA                                                         6                                                                           3                IC6                       220uF
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                2




                                                                                                                                                                                                                                                                                           C38          2                                                    C36                      -             TL072                                                    7       +              5                 1           2
                      0°                   IC4F                              +12V                        N=1                                                                                                            R11                                                           1           2          IN2                             C39             100nF                                                                                   2       2
                                                                                                                                                                                                                                                                                                                                                                                      4




                                                                                                                                                                                                                                                                                                                                                                                                                                                                     -
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                1




                                         74AHC04                                                                     5                                                                                                  68R                                                                                                                  330nF                                                                                                                            LM386N
                                                                                                                                                                                                                                                                                                                                                         1




                                        13      12                                                                   4             N=3                                                                                                                                                     10nF                                  5       2           1                                    R13                                                     RV4                                                 R12
                                                                                                                                                                                                                   2




                                                                                                                                                                                                                                                                                                                                                                                                                                                                     4
                                                                                                                                                                                                                                                                                                                                                                                                                                                                     8
                                                                                 1


                                                                                              1




                                                                                                         N=1                                                                                                                                                                                            6           OUTB                                                         1                  2                                             10K                                                 10R
                                                                    C40                                                                                                                                                                                                R14                 C42               OSCA                8
                                                                                                                                                                            0°                                                                       90°                                                                                       +5VRx
                                                                                                                                                                                                                                                                                                                                                                                                                                            3




                                                                    100nF                            C41             3             2                                                                                                                           1             2        1           2     7         VCC            3                                                      22K
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                1 2
                                                                                                                                                                                                                                                                                                                                         1




                                                                                                     10nF                N30                                                                               IC7A                                                                                              OSCB GND                                                                 C44                                 C93
                      Buffer / Driver                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        To Control
                                                                                 2


                                                                                              2




                                                                                                                                                                                                                                                                                 1




                                                                                                                                                                                             +5V           74AHC74                               +5V                   1K                  10nF             NE612                             C43                                1              2                     2             1
                                                                                                                                                                                                       4                                    14                                                                                                100nF                                                                                                                                                       C45                            +12V             P3
                                                                                                                                                                                                                                                                                                                                                                                                                                        1




                                                                                                                                                                                                       2       PRE             VCC          5                                         R15                                                                                             4n7F                                330nF                                                                           100nF
                                                                                                                                                                                                                                                                                                                                         2




                                                                                                                                                                                                               D                 Q                                                    68R                                                                                                                                                                                                                                                             1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                2




                  +6VTx                                                                                                                                                                                3                                                                                                                                                                                                                                    R7                                                                                                        2
                                                                                                                                                                                                                                                                                 2




                                                                                                                                                                                                               CLK                                                                                                                                                                                                                          1K
                                                           IC8A                                                                                                                              +5V                                            6                                                                                                                                                                             C94
                                                     14




                                                                                                                                                                                                                                                                                                                                                                                                                                        2
                         1




                                                           74AHC04                                                                                                                                     1                         Q          7                                                                                                                                                                         2             1
              C48                            1               2                                                                                                                                                 CLR             GND
                                                                                                                                                                                                                                                                                                                                                                                                                                        2




              10nF                                                                                                                                                                                                                                                                                                                                                                   +ST                                  330nF
                                                                                                                                                                                                                                                                                                                                                                        C47
                                                                                                                                                                                                                                                                                                                                                                                                                                             C46
                         2




                                                     7




                                                                                                                                                                                                                                                                                                                                                                  2              1                                                           100nF
                                                                               Q2                                                                                                                                                                                                                                                                                                               IC9
                                                                                                                                                                                                                                                                                                                                                                                                                                        1
                                                                                              2




                                             IC8B                            IRF510                                                                                                                                                                                                                                                                                    100nF                8                               3                    R16
                                             74AHC04                                                                                                                                                                                                                        ÷4                                                                                                                      VCC           OUT                            10K             +ST
                                         3        4                                  1                                                                                                                                                                                                                                                                                                      2                               4           2                1
                      IC8D                                                                                                                                 +5V                                                                                                                                                                                                                                      TR            RES
                                                                                              3
                                                                             1




                                                                                                                                                                                                                                                                                                                                                                    1




                      74AHC04              IC8C                                                                                                                                                                                                                                                                                          Side tone                                          5                               7                            R17           +ST
                  9        8               74AHC04                               R19                                                                                                                       IC7B                                                                                                                                                                                     CV            DIS                            1                    2                                               PSU
                                                                                                                                                            1




                                         5      6                                10K                                                                                                    +5V                74AHC74                                                                                                                       generator                                          1                               6
                                                                                                                                                                                                                                                                                                                                                                                                                                            1




                                                                                                                                                     C52                                             10                                                                                                                                                                                             GND           THR                                    10K
                                                                                                                                                                                                                                                                                                                                                                    2




                                             IC8E                                                                                                    10nF                                            12        PRE                          9                                                                                                                                                                                                     R18
                                                                                                                                                                                                                                                                                                                                                                                                    LM555
                                                                             2




                                             74AHC04                                                                                                                                                           D                   Q                                                                                                                                                                                                              8K2                                                                     IC11
                                                                                                                                                            2




                                        11        10                                                                                                                                                 11                                                                                                                                                            C49                                                                                                                                +12V                78L05                           +5V
                      180°                                                                                                                                                                                     CLK                                                                                                                                                 100nF                                                                                                                                              3                       1
                                                                                                                                                                                                                                                                                                                                                                                                                                            2




                                             IC8F                                                                                                                                        +5V                                                8                                                                                                                                                                                                                                                                              VI           VO
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             1




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  1




                                             74AHC04                                                                                                                                                 13                            Q
                                        13        12                                                                                                                                                           CLR                                                                                                                                                                                                                                                                                C53                                                     C54
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  100nF                                                   10uF
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                2




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           16V
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             2




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  2




                                                                                                                                                                                                                                                                                                                                                                 SW3                                                                                     +12V
                                                                                                                                                                                                                                                                                                                                                                       1                                                                                                          SW2B          +ST
                                                                                                                                                                                                                                                                                                                                             ON/OFF
                                                                                                                                                                                                                                                                                                                                                                                           1




                                                                                                                                                                                                                                                                                                                                                                                                              1




                                                                                                                                                                                                                                                                                                                                                                                                                                1




                                                                                                                                                                                                                                                                                                                                                                       2                                                                                                                                                  IC12
                                                                                                     18.667 - 19.133MHz                                            56 - 57.4MHz                                                                                                                                                                                                                                                                                          RX             1
6.222 - 6.377778MHz                                                                                                                                                                                                                                                                                                                                                                             C55                   C56           R20                                                                                   78L06                           +6VTx
                                       R22                         +5V                                           R21                                                                                                                                                                                                                                                                            220uF                 100nF         10K                                                 2                             3                       1
                                       10K                                   C57                         1                2                                                     R23                                                                                                              IC13A                                                           BATT1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                         TX             3                                  VI           VO
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  GND
                                                                                                                                                                                                                                                                                                                                                                                           2




                                                                                                                                                                                                                                                                                                                                                                                                              2




                                                                                                                                                                                                                                                                                                                                                                                                                                                 1




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             1




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  1




                                   1                  2                  1               2                                                                                      10K                                                                                              +5V             74AHC74                   +5V               +12V
                                                                                                                                                                                                                                                                                                                                                                                                                                2




                                                                                                                 10K                                                   1                2                                                                                                   4                         14                                               1                                                                2            Q3                                           C58                                                     C59
                                                                             10nF                                                                                                                                                                                                           2     PRE        VCC      5                      BATTERY                   2                                                                             2N2905                                       100nF                                                   10uF
From DDS
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                2
                                                                                                                                                                                                                                                                                                                                                                                                                                1




                  C60                                                                                                                                                                                IC14D                                                                                        D            Q                                                                                                                                                                                +12V                                                       16V
                                                                   14




                                                                                                                                                                                                                                                                                                                                                                                                                                                 3




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             2




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  2




P4                10nF                                                               C61                                               IC14C         C62                                                                                                                                    3                                                                                                                                       R24                     +ST                   SW2C
              1            2       13                 12       1             2 2               1             3            4        5           6 1          2              11           10       9             8                                                                                  CLK                                                                                                                               1K
     1                                                                                                                                                                                                                                      IC15                                     +5V                              6
                                                                                                                                                                                                                                                                                                                                                                                                                                                                         RX             1
          1




                                                                                                   2




                                                                                                                                                                 2




     2                                   IC14F                                       68pF                    IC14B                     74AHC04       18pF                  IC14E                     74AHC04                            4                              6                    1                 Q       7                                          SW4                                                                                                                    2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                         TX
                                                                   7




                                                                                                                                                                                                                                                                                                                                                                                                                                2




              R25                        74AHC04                                                             74AHC04                                                       74AHC04                                                      3       D0            W                                   CLR       GND                                                                                                                                                                         3                                 IC16
              330R                                                                                       C63                                                           C64                             +5V                              2       D1                     5                                                                                               1                                                                                                                                                  78L05                           +5VRx
                                                               IC14A                                     560pF                                                         150pF                                                            1       D2             Y                                                                                 KEY                   2                                                                                                                                              3                       1
                                                                                                                                                                                                                                                                                                        ÷2
                                                                                                   1 1




                                                                                                                                                                 1 1




                                                                                                                                                                                                          1




                                                               74AHC04                                                                                                                                                                 15       D3                                                                                                                                                                                                                                                                         VI           VO
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  GND
          2




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             1




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  1




                                                                                                                                                                                                                                       14       D4
                                                                                                         L9                                                                                      R26                                   13       D5                                                                 IC13B                                                                                                                                                                          C65                                                     C66
                                                                                                         1u2H                                                          L10                       10K                                   12       D6                                                                 74AHC74                               +5V                                                                                                                                      100nF                                                   10uF
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                2




                                                                                                                                                                       470nH                                                                    D7                               +5V                        10                                                                                                                                                                                                                                             16V
                                                           Multiplier
                                                                                                                                                                                                          2




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             2




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  2




                                                                                                                                                                                                                                       11                                                                   12     PRE                   9
                                                                                                                                                                                                                                                                                                                                                             1




                                                                                                                                                                                                                                       10       A                      16                                          D                 Q
                                                                                                   2




                                                                                                                                                                 2




                                                                                                                                                                                                                                        9       B            VCC                                            11                                   C67
                                                                                                                                                                                                                                                                                     1




                                                                                                                                                                                                                                        7       C                      8                                           CLK                           10nF
                                                                                                                                                                                       SW1C                                                     G            GND                           C68                                           8
                                                                                                                                                                                                                                                                                                                                                             2




                                                                                                                                                                                                                                                                                           10nF             13                       Q                                                                                                       Title
                                                                                                                                                                       40m                                                                      74AC251
                                                                                                                                                                                             1                                                                                                                     CLR
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  40/20m CW Tranceiver - TX & RX
                                                                                                                                                                                                                                                                                     2




                                                                                                                                                                                             2
                                                                                                                                                                       20m                   3                                                                                                                                                                                                                                               Size            Document Number                                                                                    Rev
                                                                                                                                                                                                                                                                                                                                                                                                                                               A3                                                 20/40m TRX                                                      02

                                                                                                                                                                                                                                                                                                                                                                                                                                             Date:                   Wednesday, November 16, 2005                 Sheet           1          of           2
                                                                             R2 7
                                                                      1               2                                                                                                                                                               DISPLAY
                                                                                                                                                                                 IC17                                                             DSPL1




                                                                 1




                                                                                          1
                                                                             10K                                                                                                                           39                             35
                                                                      R2 8                    C6 9                                                                           2            SEG1             38                             34          SEG1
                          SW5                                         10K                     100nF                                                                             LOAD      SEG2             37                              7          SEG2
                                        A                                                                                                                                   40            SEG3             33                              6          SEG3




                                                                                          2
                                1       B                                                                                                                                       CL K      SEG4             32                              5          SEG4
Rotary Encoder




                                                                 2
                                2       C              +5VD1                                                                                                                34            SEG5             29                             36          SEG5
                                3                                                                                                                                               DATA IN   SEG6             28                             37          SEG6
                                4                              +5VD1                                                                                                        35            SEG7             27                             30          SEG7
                                                                             R2 9                                                                                               DATA OUT SEG8              26                             29          SEG8
                                                                      1               2                                                                                                   SEG9             25                             11          SEG9
                                                                                                                                                                                         SEG10             24                             10          SEG10




                                                                 1




                                                                                          1
                                                                             10K                                                                                                         SEG11             23                              9          SEG11
                                                                                              C7 0                                                                                       SEG12             22                             31          SEG12
                                                                      R3 0                    100nF                                                                                      SEG13             21                             32          SEG13
                                                                      10K                                                                                                                SEG14             20                             25          SEG14




                                                                                          2
                                                                                                                                                                                         SEG15             19                             24          SEG15




                                                                 2
                                                                                                                                                                                         SEG16             18                             15          SEG16
            R3 1                                                                                                                                                            31           SEG17             17                             14          SEG17
   +5VD1    10K                                                +5VD1                                                                                                            LCD      SEG18             16                             13          SEG18




                                                                                                                                                                   1
      1             2                           IC18                                                                                                                                     SEG19             15                             26          SEG19
                                                                                      17                                                                                   C7 1          SEG20             14                             27          SEG20
                        1




                                        16                                RA0         18                                                                                                 SEG21             13                             21          SEG21
                                                 OSC1/CLKIN               RA1                                                                                              47pF          SEG22                                                        SEG22
            C7 2                                                                      1                                                                                                                    12                             20




                                                                                                                                                                   2
            22pF                                                          RA2         2                                                                                                  SEG23             11                             19          SEG23
                                                                          RA3         3                                                                                                  SEG24             10                             18          SEG24
                        2




                                                                     RA4/CLK1                                                                                                            SEG25             9                              17          SEG25
                                                                                                                                                                                         SEG26             8                              22          SEG26
                                        15                                            6                      R3 3                                   +5VD1                                SEG27             7                              23          SEG27
                   R3 2                          OSC2/CLKOUT          RB0/INT         7                      1K                                                               1          SEG28             6                               4          SEG28
            1               2               4                            RB1          8                  1              2                                                       VDD      SEG29             5                               8          SEG29




                                                                                                                                                             1
                                                 MCLR                    RB2          9                                                                                                  SEG30             4                              38          SEG30




                                                                                                                            1
   +5VD1           10K                                                   RB3          10                                                        C7 3                        36           SEG31             3                               3          SEG31
                                        14                               RB4          11                         C7 4                           100nF                           VSS      SEG32             30                             40          SEG32
                                                 VDD                     RB5          12                         47pF                                                                       BP                                             1          BP




                                                                                                                                                             2
                   1




                                            5                            RB6          13                                                                                         AY0438                                                               BP




                                                                                                                            2
           C7 5                                  VSS                     RB7                                                                                                                                                                      DISPLAY1
           100nF                                PIC16F84                                                     R3 4                                                                                                                                                        C7 6                       C7 7




                                                                                                                                                                                                                               2
                                                                                                             1K                                                                                                                                                          8p2F                       8p2F
                   2




                                                                                                         1              2                                                                                                              R4 2                          1          2               1           2
                            SW6                 +5VD1                                                                                                                                                                                  330R                                                                             DDS OUT
                                                                                                                            1
                                                                      R3 5                                                                                                                                                                        C9 5
                                    1                          1              2                                  C7 8                                                                               IC19                                          10nF                   L11                        L12                      P5
   Band Change




                                                                                                                                                                                                                               1
                                    2                                                                            47pF                                                                          7                          14                  1          2       1                  2       1                   2
                                                                                  1




                                    3                                 10K                                                                                                                      8     SCLK          IOUT                                                  8u2H                       8u2H                     1
                                                                                                                            2




                                                                                                                                                                                                                                                             1




                                                                                                                                                                                                                                                                                        1




                                                                                                                                                                                                                                                                                                                    1
                                                                                      C7 9                                                                                                     9     SDATA                             C8 0        +5VD1                                                                     2
                                                                                      100nF                  R3 6                                                                                    FSYNC                16     1                2              C8 1                       C8 2          C8 3
                                                                                                             1K                                                                                                   COMP                                           82pF                       150pF         82pF
                                                                                                                                                         X1
                                                                                  2




                                                                                                         1              2               +5VD1            50MHz                                12                                       10nF




                                                                                                                                                                                                                                                             2




                                                                                                                                                                                                                                                                                        2




                                                                                                                                                                                                                                                                                                                    2
                            SW7                 +5VD1                                                                                               4                       3                 11     PSEL0                2
                                                                                                                            1




                                                                      R3 7                                                                               V          OUT                       10     PSEL1       REF IN                C8 4
                                                                                                                                            1

                                    1                          1              2                                  C8 5                                                                                FSEL                 3      1                2
                TX/RX
                                                                                                                                                               G

                                                                                                                                                                    G
                                    2                                                                            47pF                                                                                           REF OUT
                                                                                  1




                                    3                    +5VD1        10K                                                        C8 6                                                                                                  10nF
                                                                                                                            2




                                                                                                                                                             1

                                                                                                                                                                   2
                                                                                      C8 7                                       10nF                                                          6                          1
                                                                                                                                            2
                                                         1




                                                                                      100nF                                                                                                          MCLK        FS ADJ




                                                                                                                                                                                                                                         1
                                                  R3 8                                                                                                                  +5VD1
                                                                                  2




                                                  10K                                                                                                                                         15                          13                      R3 9
                                                                                                                                                                                   +5VD1             AVDD         AGND                            3K9
                                                                                                                                                                            1
                            SW8                                       R4 0                                                                                                                     4                          5
                                                         2




                                                               1              2                                                                                    C8 8                              DVDD         DGND




                                                                                                                                                                                                                                         2
                                                                                                                                                                                        1
                                    1                                                                                                                              100nF                            AD9835BRU
                Step
                                                                                  1




                                    2                                 10K                                                                                                                   C8 9
                                                                                                                                                                            2




                                                                                      C9 0                                                                                                  100nF
                                                                                      100nF
                                                                                                                                                                                        2
                                                                                  2




                                                                                                                        IC10
                            P6                                                                                          7805                        +5VD1
                                                  +12V                                                              1                       3
                                    1                                                                                       VI         VO
      POWER
                                                                                                                                 GND
                                                                                                             1




                                                                                                                                                1




                                    2                                                                                                                                                                                          Title
                                                                                                      C5 0                                              C5 1                                                                                          40/20m CW Tranceiver - DDS & Control
                                                                                                      10uF                                              10uF
                                                                                                                                 2




                                                                                                      16V                                                16V                                                                   Size           Do cument Number                                                                    Re v
                                                                                                             2




                                                                                                                                                2




                                                                                                                                                                                                                                 A4                                                 20/40m TRX                                      01

                                                                                                                                                                                                                               Da te:             Wednesday, November 16, 2005                      Sheet           2   of   2

				
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