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MAINTENANCE
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MODEL
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E L E C T R O N I C S C O c e a n s i d e ,a i l o r n i a
OPERATION and MAINTENANCE MODEL 4OO SERIES S]NGLE SIDEBAND TRANSCEIVER
INTRODUCTION
The Swan Model 400 Single Sideband Transceiver, together with its accessorre6 and optional equiprnent, is designed to be used in either CW or SSB mode6 on all portionB of the 80-, 40-, 20-, l5-, and I0-meter amateur radio bands. Operation on AM (Single Sidebaltd rrith Carrie!) is possible by zero-beating the !eceived signal. The Swan 400 generates the single sideband signal by mean6 of a crystal lattice and the tran6ceive op€ration autofilter, to the matically tunes the transmitter Provi6ions a!e receivedfrequency. included in the transceiver Jor ope!ation on either upper or lower sideband, and provisiong for cohplete band coveraSe are included within the basic
microphone is possible by use of the FuDction Switch or the VOX acces sory. T h e b a s i c t l a n s c e i v e ! i B d e B i g n c df o r use with either the Model 410 Frequency Control Unit, which provides full coveiage of all portions o{ the amateur bandd, or with the Model 4068 Frequency Colttlol Unit which providea coveiage of all phone portiona of the 80 throrrgh l5 rneter bandE and a 500 kc portion of the l0-meter band, With a suitable power 6upply, operation may be fixed, portabl€ or hobile. Power input on all banda exceeds 400 Watts, PEP, on single sideband, and 320 Watts DC input on CW. The baaic t ranac e ive r includeB autoDatic gain control, (AGC) automatic lirniting control, (ALC), aelectable sideband, grid-block keying, calibrator, and speaker Part I of this Manual covers the basic transceiver. Parts II and lfl cover the Models 4068 and 410 Frequency Conttol Unita, !e6pectively. Part IV covers the recohEended power Bupplies, Model ff7-XB or ll?-XC lor ac operation and Model l4-ll7 for l2 volt dc operation. Models a!e also available for 230 volt AC oDeration.
Ba6ic circuitry of the single conversion de6ign has been proven in thouaands of hours ot opeiation of the very popular Swan 240 and 350 series of transceivers. electrical, and thermal Mechanical, are exceptionally high, and all stability are voltage legulated and oscillators PuBh-toternperature cornpensated. talk opeiation is po6sible in aU installatiolrs, and operation with a tv,/o-contact
E L E C T R O N I C S
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C O R P .
I MODEL 4OOTRANSCEIVER SPECIFICATIONS
FREOUENCY RANGES
Foll frequency coverage of 80, 40, 20, I5, and l0 meter amateur radio bands in 8 ranges oJ 500 kc each, as Iollows: 3 , 5 - 4 . 0 , 7 . 0 - 7 . 5 , t 3 . 8 5 - 1 4 . 3 5 ,2 1 . 0 2 r , 5 , 2 8 . 0 - 2 8 .5 , 2 8 . 5 - 2 9 . 0 , 2 9 . 0 29.5, 29.2-?9.1rnc. Model 4068 Frequercy Contlol Unit Full phone band coverage of 80, 40, 20, and l5 meters, plus a 500 kc segmentof l0 lneters, as follows: 3. 8 - 4 . 0 , 7 . r - 7. 3, 1 4 . r 5 - r 4 . 3 5 , 2 1 . 2 5- 2 1 . 4 5 , 2 8 . 5 - 2 9 , 0 r n c . POWER INPUT
Sinele Sideband Su
Car!ie!
400 Watts PEP,
Watts DC input on all bands, AM (Sinsle Sideband With Carrier) IZ5 Watts DC input on all bands. DISTORTION Distortion products downat least30 db. UNWANTED SIDEBAND SUPPRESSION Unwanted sidebaDd downat least40 db. CARRIER SUPPRESSION Carr:ier suppression at Ieast 50 db, RECEIVER SENSITIVITY Less than 0.5 Inicrovolt at 50 ohms to irnpedanc e for 6ignal-plus-noise noise ratio of I0 db. AUDIO OUTPUT AND RESPONSE Audio output through built-in speaker approx. 3 watts to 3,2 ohrn load. Response essentially flat 300 to 3000 cps on both teceive and transmit. METERING 0-800 rrla on PA Cathode current, tran6mit S-Meter, 0-?0 db over 59 FRONT PANEL CONTROLS Function Switch, Sideband Selector, Phone-CW, AF Gain, Bandswitch' Mic. Gain, Carrier Balance, PA Plate Tune, PA Grid Tune, PA Load Coarse, PA Load Fine, VOX-PTT REAR PANEL CONTROLS AND CONNECTORS Grid -Block CW Bias Potentiometer, key jack, Jones plug powe! connecto!, VOX Connector, F requency Control Unit Connecto!, Antenna, S-Meter Zero, SPDT Relay Terrninal. FREOUENCY CONTROL UNIT CONTROLS Main Tuning, RF Gain Bardswitch,
cw -320
bands.
VACUUM TUBE COMPLEMENT Vl - 6EW6 VFO Amplifier YZ - IZBE6 Transrnitter Mixer vJ - ou.t\.o.urrver V4 - 6HF5 Power Amplilier v) - bill ) rowe r Arnprlri e r V6 - IZBZ6 Receiver RF Amplifier Y? - IZBE6 Receiver Mixer V8 - 6EW6 First IF Amplifier V9 - l28.q.6 Second IF AmPlifier Vl0 - IzAX7 Product Detector/Receiver Audio v t r - 6BN8 AGC Amplifie r/ Detector y l z - 6GK6 Audio Output v l 3 - l2I}A6 I00 KC Cryslal Calibrator v l 4 - 7360 Balanc€dModulator v l 5 - 12I}A6 Carlier O scillator v l 6 - I ZAXT Mic. Amplifier / Transrnit Vl?- OAZ Voltage Regulator DIODE AND TRANSISTOR COMPLEMENT 2 N 7 06 O s c i l l a t o r QI,i 2N706Emitte r Follower QZ* D40l TS -2 ALC Diode D4oz TS -2 ALC Diode D60l TS-2 S-Meter Delay Dl?01 IN29?4A Zener Voltage Regulator i. Transistor cornplement identical for eithei Model 4I0 or Model 4068 Frequency Control Unit. TRANSMITTER OUTPUT IMPEDANCE Wide - range Pi-network output matche8 a n t e n n a se 6 s e n t i a l l y r e s i s t i v e a t 2 0 t o 300 ohms impedance with provision8 for both coarse and fine adju6t, POWER REOUIREMENTS Filarnents 12. 6 volts, 5.5 amp
ReIay Bias Medium
Voltage
12 volt6 dc, 250 ma - I l 0 volts dc, 100 rna 2?5 volts dc, 150 ma
800 volts dc, 500 rna High Voltage DIMENSIONS Model 400 Transceiver 5-l/2 ir'. high, l3 in. wide, IL in. deep Model 410 Frequencv Control Unit 5-l lZ A, t^rgn, 6-l/2 in. wide, I I in. deep Control Unit
3 in, high, 1-3/4ir,. wide, 5 in. deep.
WEIGHT Mode] 400 Transceiver: Model 410 Frequency Control Unit Model 4068 Frequency Control Unit
t7lb, '91b. 3 lb.
2
PART I
MODEL 4OOTRANSCEIVER
CIRCUlT THEORY
GENERAL DISCUSSION The Sr ran 400 Transceiver plovides siagle s i d e b a n d ,B u p p r e s s e dc a ! r i e r t r a n € c e i v e operation; and generates the Bingle sideband eignal by mean6 of a crystal lattice To permlt a logical diEcussion of filte!. thi6 lnode of operation, certain definitions ate nece€5aly, In a normal AM signal (double dideband with carrier), a radio frequency i6 modulated with an audio Jrequency signal. This is considered by many to be merely a ca8e of varying the amplitude of the carlie! at an audi.o rate. In fact, howeve!, there are actual.ly sideband frequencies generated which ale the !eBults of mlxing the RI. and A!' 6ignal3. These sideband3 are the suh ot, and the difference between the two hetelodyned 6ignals. For detection by means of conventional diode detectols, the two sidebands are mixed with the carlier to detect aDd to demodulate the audio intelligence. This inef{icient hean€ of transrnis sion p€rrnits only approximately 25 per cent of the full tlanahitted power to b€ used to tras6lnit intelligence. There are other attendant drawbacks, also. The bandwidth of the transmitted 6igna1 is on the order of 6 kc, while the actual dehodulated audio is 1e66 than 3 kc. The lesult i. very limited use of the band, and over half of the allotted frequency range iB unuaable becauge oI heterodyne6, ioterference, and congestion. In the single sideband, suppressed carlier rrode of transhioeion, only ono sideband of the Rr. and AF heterodyned signal is tranBmitted, the other sideband and the carrier being Buppressed to a level which effectively permits using only the audio intelligence bandwidth. This results in increasing the transrnission efficiency many times ove!, and pellnits an effec tive doubling of the use of the allocated frequenciea. It rnust be remerrlbered that in the single aideband, suppresned calrier mode of transhission, both the unn,anted sideband and the calrier ale oaly Buppressed, not entile1y eliminated. Thu6, with a transmitted sigDal frorn a transmittei with 40 db sideband 6uppression, the other, or unwanted sideband is pleBent, and it i6 transrnitted, but its leve1 is 40 db below the'wanted sideband. When
3
I MODEL,lOO RANSCEIVER T A. Circuit Theory (cont)
BLOCK DIACRAM, RECFJIVE
B],OCK DIACRAM, TRANSMIT
FIGURE 3
CRYSTALFTLTER,TYPTCAL CHARACTERISTIC
I MODEL 4OOTRANSCEIVER A. Circuit Theoiy (Cont) this signal is leceived at a level of 20 db over 59. the unwanted sideband will be pre6ent at a leve1 oI approximately 55. The sahe is true of carrie! guPPression. With carrier suppressionof 50 db, and a signal level of 50 db over 59, carlier will be present at a level of approxirnately 53 to 54. In the Model 400 Transceiver, the single sideband, suppressedcarrie! signal is generated by the crystal lattice filter method. Refer to the schematic diagram' and to FiSule6 I and 2, Block Diagrams SIGNAL CENERATION In the TRANSMIT position (i. e., when the pu6h-to-talk switch on the lnicroPhone i3 pressed ot when the Function Switch is moved to TRANSMIT), the transmitter portion of the transceivel is activated, and generates a sinSle sideband, suppressedca!!ier signal in the follow_ i n g m a n n e r : C a r r i e r i s S e n e r a t e db y V l 5 , Carrier Oscillator, which is a Pierce oscillator, with the crystal oPerating in parallel resonance. This stage operates in both th€ ttansoit and leceive rnodes. When transmitting, the RF outPut oJ the oscillator is injected into the control grid of the Balanced Modulator, VI4. This balanced modulato! is a beam deflection type, and opeiates 5imila! to a cathode ray tube in that the elect!on bearn frorn the cathode i6 deflected to one outPut plate or the other by the charge aPPear_ ing on the deflection Plates. The RF energy fed to the cootrol Srid of the balanced modulator appeals on both plates oI the output, in the absence of signals to the deflection plates. The two output plates feed the carrier to Trans_ forrner Zl40I in push PuU, and the two RF signals cancel each other out in the The defl€c output ot the transforn:rer. tion plate reference voltages are adjusted bv means of the ca!rier balance control 60 that with no audio, the RF being Ied to the output plates will cancel out' and the output lror'j. Zl40l will be zero, Audio from Microphone Amplifier Vl6 is superilnposed on one deflection Plate, thereby unbalancinS lhe modulator, and the two sideba$ds resulting froh the 3uln and diff€rence frequencies of the audio and carrier appear as a double sideband, suppressed carrier si8na1 in the outPut The catrier o{ Translormer Zl40l. suppression is aPproximately 50 db. The double sideband, suPPressed carrier siSnal is then couPled to the crystal filter' which euppreeees one sideband, and permit6 the other sideband to be fed to the First IF Amplifier, V8. The carrie! frequency crystal alrd the filte! crystalg are selected so that in the LSB poBition on 4O and 8O hete!s, the sideband siSnal is Senelatedwith a calrier frequency of 5l?2. 8 kc, and this siSnal \till fall within the bandpass of the filt€r 6uch that the lower 6ideband will be attenuated by at least 40 db. See Figure 3. On the USB positron of 40 and 80 meiers, the carrier clystal is 5I?6.8 kc, which positiond the double 6ideband signal on the other side of the response culve oJ the filter, attenuating the upper sideband by at Ieast 40 db. In lhe single conversion mixing proces6, these sidebands become inverted. OnZ0, 15, and l0 meters, where oPeration i6 generally on upPer sideband, the siBnaI i6 generatedwith the same carrier crystal used in generating the lower sideband on 40 and 80 meters. The five crystal filter used in the tranaceive! results in an improved reaPonae characteristic on the low frequency end of the bandpass, and advantage is taken of this eflect to provide better sideband suppression on the lnost used 6ideband for each frequency band,
4OO TRANSCEIVER I IV{'IEL A. C i.cuit Theory (Cont) The single sideband, suppressed carrier is fed signal Jrom the First IF Amplilier to the Transmitter Mixer, V2, u'here signals Irom the VFO Amplifier are mixed, and the resultant signal at the final transmitted frequency is alnplified through the Transrnitter Mixer, the Driver, V3, and the Power Amplifiers, The signal from the VFO V4 and V5. Amplifier iE initiated in the particular Frequency Control Unit being used. The signal frorn the Frequency Control Unit is routed to the VfO Amplilier, and on is subtractively 40 and 80 rneteis, mixed with the single sideband signal On 20, 15, and from the IF AmpliIier. l0 meters, the frequencies are additively mixed, resulting in output on the opposite sideband, thc gain oI the First When in TRANSMIT, II Amplifier is controlled through the Automatic Limiting Control network D40l-402, etc., to control the gain of the stage in response to the average input power to the power amplifiers. This ALC system will cornpensat€ {or any extremely strong input signaLs, but does not completely eliminate the necessity of proper adjustrnent ol the Mic. Gain Although this feature wil] Control. prevent the transmitter Jroln flat-topping and spurious ernissions, considerable distortion may occur if the Mic. Gain control is not properly adjusted. Refei to Operating Instructions. TUNE AND CW OPERATION the Jrequency oJ the carrier Normally, oscillator is approximately 300 cps outside the passband of the crystal lattice filter. In TUNE position, to enable the to be tun€d to the maximum transmitter power output condition, the frequency of the carrier oscillator is moved approximately 500 cps to place it well within the passband ofthe cry6tal lattice filter, At the sarne tirne, one d€flection plate of the balanced rnodulator is grounded, unbalancing the modulator and allowing full carrier input for tuning puiposes, A similar procedure is followed in the CW position of the Phone -CW switch, to allow output duiing CW operation. full carrier During CW operation the cathode of V168 i6 opened from grotrnd, cuttrng ofI the tube. This allows CW operation with no danger of pickup of audio through an open microphone, Attempts to operate on CW by keying the lnicrophone jack, and inserting carrier, are not recommended. RECEM In RECEIVE position, or at any time when the transrnitter is not in TRANSMIT or STANDBY, all circuits used in transmitting are disabled throrgh the relay controlled circuits, thc relays being energized Ior transmitting, and de-energrzcd for receiving. Rclay K2, when de-energized, allows signals frorn the transrnitting tank circuit and antenna to be ted to the Receiver RF Amplifier, V6, where thcy are amplilied, and then {ed to the control giid oI the Receiver Mixer, V?. The local oscillator signal from the VFO Amplifier is now used to heterodyne the received frequency to the IF frequency, either upper or lower sideband. A11IF arnplification is accomplished at this Jrequency, nominally 5l?4.5 kc, and in the Product Detector Vl0A, the IF lrequency is heterodyned with carrier frequency generated by Carrier Oscillator, VI5, to res$lt in detection of the sarne sideband used to generate the transmitted signal. It i6 not possible {or the transceiver to thus receive a 6ignal on any frequency other than that to which the trarlsrnitter is tuned, nor to detect the wrong sideband. This simple single conversion de6ign results in an extrelnely stable signal, and an image response down more than 80 db. Since the VFO frequency from the
1 MODEL 4OO TRANSCEIVER A. Circuit Theory (Cont) Frequency Control Unit is deterrnined by circuit elements which are far removed frorn any heat source, and the voltage regulation is very precise to the transistor oBcillator, frequency stability is good. extiemely Automatic Cain Control, (AGC) is provided by the AGC Amplrfier/Detector, VlI, which provides an AGC signal for control of the gain of V6, Receiver RF Amplifier, V7, Receiver Mixer, and V9, lated, i5 considerably 500 \ratts, or rnore, more, tyPically
TRANSM]T
AND RECEIVE
SWITCH]NC
AII transmit and receive ewitchrng i6 performed by relays Kl and K2. In TRANSMIT position, only those tubes that opelate in the transmit mode a!e operative, aU others being biased to cutoff through the relay contacts, In the position, with the relay deRECEM energlzed, the tubes that are norhally used only in tran3mittiDg are cut oft in Relay K2, which the sarne manner. when de-energized feeds signals frorn the output pi-network to the receiver, and is used also to control any external In the TRANSMIT po3ition, switching. the meter indicates the cornbined cathode current oI the two Power Amplifiers. po6ition, it indicates the In the RECEM voltage acro6s R902 in the cathode of the Second IF Amplifier, V9, which is iDversely proportional to the AGC voltage used to control the gain of the tube. Thus the S-Meter reads le{t to right on transmit, and right to left on receive. POWER RATING The Swan 400 is capable of 400 watts, PEP input under steady two-tone te6t .onditions, when operated with any of The the recommended power supplies. peak envelope power, when voice modu-
Recommended power supPlies produce a no-load plate voltage ol approximately Under TUNE conditions, or 925 volts. CW operation, this voltage rnay drop to as Iow as ?20 volts. Under steady state the voltage will two-tone modulation, 750 volt3, If Power to apploxirnately drop idling current is 50 rna, and Amplifier ju8t before flattwo tone plate current, topping, is 3?5 ma, the peak two -tone cullent will be 560 rna. The PEP input wiu then be ?50 volts x 560 ma = 420 watts, beca[rBe average Under voice modulatio!, Iess' the Pow€r power i6 considerably plate and screen voltages will Amplifier be mainta)ned hiSher, even during voice peaks, by the power supply filter capacitors. Peak voice plate cu!rent will thelefole also be higher than with two-tone Under typical operatinS test conditions. conditions, peak plate current befole flat-topping will be 625 lna at 800 volts, to result in a peak envelope power inPut of 500 watt8. Reading6 ol cathode current would not reflect this 500 watt power inPut' however, because oI the dampiDg in the The meter dampcathode current meter. ing i6 such that the rneter i3 unable to respond to variations oJ cathode current Cathode current in the audible range. readings under normal voice input, should not exce€d approximately I50 to 175 rna. POWER AMPLIF]ER PLATE DISSIPATION
There is olten a mi s und€ r standing about the plate dissipation of tubes operated as under voice modulation, AB ampliliers In the Swan 400, while in the transmit the plate position, and with no modulation' the plate current voltage will be 890 vo1te, 50 rna, and the power input will be 50 watts.
I MODEL 4OOTRANSCEIVER A, C ircuit Theory (Cont) Authorities agree that the average voice power is l0 to 20 db below peak vorce power. Normally some peak clipprng in the Power Amplilier ( an be tolerated, and a peak-to-average ratio oJ only 6 db rray sometimeg occur. unde! such a condition, the average power input will be 125 \ratts, and plate current will be about 156 rna. With an average Po'\r/er Amplilier efficiency of 55 per cent, plate dissipation wilt be 57 watts, or 28, 5 watts per tube. The 6HF5 is rated at 28 watt6 continuous duty cycle in normal TV service. Thus it can be seen that under normal operating conditions th€ PA tubes in the Swan 400 are not being driven very hard. Only dLrring the tune up is there any need to exercise caution by lirniting the length of time the unit is held in the TUNE position to about 30 secondsat a time,
B.
CENERAL
INSTALLATION
Power requirements for the Swan 400 are shown in the following table. Pin connections to the Jones type power connector are also listed as an aid in connecting other brands or horne-brew power eupplies. Pin High Voltage Mediurn Voltage Bias Voltage Filament Voltage Relay Voltage Nornrnal
The Swan 400 traogceiver has been designed to provide the utmost in ease of operation, stability, versatility, arld enjoyment. Maximum enjoyment Irorn your Swan will depend to a great extent on the installation. For fixed station or portable use, operation with the Model I I?XB or I t?XC power supply provides a ( ompa( t dr rdngement with maxrrnum ease oI op
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SINGLE SDEBAND TNANSCEIVER SCHEMATICDIAGRAM--SWANMODEL 4OO
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