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CONSTRUCTION NOTES ON SUPAPIX BY ZS4U Intro Congratulations on by monkey6



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CONSTRUCTION NOTES ON SUPAPIX BY ZS4U Intro. Congratulations on your purchase of the Supapix kit! This kit was developed to help restricted licensed radio hams in South Africa upgrade to the full license. This kit fulfills the requirement as set by the SARL. Just the transmitter alone when used in CW satisfies the requirement but by building a working transceiver it actually surpasses the requirement! It is accepted that the prospective kit builder has a basic knowledge of how to identify electronic components as well as a basic know how on soldering. Let’s get to building! The kit will be built in phases so as to ensure that every section operates correctly and also to minimize fault tracing once completed. You will require the following to complete the Supapix: a. b. c. d. e. f. g. h. i. j. k. l. Soldering iron capable of 40 to 60 watt. Solder – preferably the thin type +/- 1 mm. Side cutter small type. Long nose pliers. Small brass screw driver or plastic trimmer to adjust C16. Magnifying glass for component markings and solder inspection. A receiver capable of USB reception. A watt meter capable of measuring a minimum of 1 watt. 50 ohm dummy load. Build your own – see NOTE on Page 8. 9 V or 12V battery – NO electric power supplies!! An electric drill with bits. A pair of scissors and some Bostik for the decals.

Once you have all the tools ready proceed to pack out your components. The best is to group the different types together example – all resistors together; all capacitors, transistors etc. Graphical component examples can be found at the end of page 9. Make a colour printout of the Supapix Component Colour document – it has all your markings and component info handy. In addition you may also use the Supapix Component Colour Silk Screen document should there be any doubt as to the placing of a component. Experienced builders might want to use the Supapix Circuit print out. Ensure that ALL the parts have been shipped to you by using the parts list on your printout – if not contact the kit vendor. Phase 1 – Local oscillator. Orientate the PC board so that the black dot on the top side is situated to the bottom right as in fig.1.

Fig. 1


It is a good time to start up your soldering iron! You are ready to proceed. Select the following components from your component groups and place them aside in a group – use your magnifying glass to see the markings on the components: a. b. c. d. e. 7020 kHz Crystal C1,2,3 & 16 R1,2 &12 Q1. Black & red wire.

Place the components on the PC board one at a time and solder them in position as indicated on your print out of the Supapix Component Colour document. You will see that the transistor casing has a little protrusion on the side – make sure it is aligned exactly as shown on your printout! When you solder try not to warm up the component connections too long as it might damage the component itself. Do not press the transistor Q1 too deep – the distance between the transistor casing and the PC board should be between 3 to 5 mm. Cut off the protruding legs of components flush with soldering. Once you have soldered the components into place you can solder the red wire into the +9-12V (red) hole and about 15 cm of the black wire into the – 9-12V (black) hole. Connect a 9/12v battery to the RED & BLACK wire – make sure about the polarity! If no smoke or heat is present you are halfway there – switch on your receiver, select 7020 kHz on USB and look for the carrier. Found it? If so then you have just built a small RF oscillator. Note that the carrier might not be exactly on 7020 kHz – DON’T worry – as long as there is a carrier within 2-3 kHz of 7020 kHz you are on the right track! Disconnect your project from the battery and back to building. If you do not pick up the oscillator proceed with fault finding procedure on page 8. Phase 2 – Switching Circuit. I hope you find it exciting so far! Select the following components and place them aside: a. b. c. d. C12,14 & 18. R6,7 & 13. D2,3 & 4. Q3 & 4.

Solder these components in place exactly as per your print out and method used with phase 1. The two small diodes D3 and D4 stands upright with the black ring at the top. Solder the yellow wire into the yellow hole marked Key. Solder the green wire onto the black hole marked Key. Cut about 5 cm off from both wires (to be used later) and remove about 5 mm of the insulation from the tips of the soldered wires. Once completed it is back to your receiver and the battery. Connect the battery to your project and switch on the receiver +/- 7020 kHz in USB mode. Connect the yellow wire momentarily with the green wire – black and yellow Key wires together. Find the carrier and turn the receiver frequency knob onto the carrier until you hear the tone comfortably – now turn the frequency knob on the receiver towards the side


where tone frequency reduces until the carrier tone is at zero beat– NO further! Disconnect the yellow wire from the green wire – keep power on. Take your brass screw driver and turn C16 until you hear the tone - slowly adjust C16 until the tone is at +/- 700 Hz – set at tone on which you want to hear the replying stations in CW. Connect the yellow and green Key wire and the tone disappears and the CW zero beat should be heard. If you have achieved this you are well on your way – if not use Fault Finding Procedure on page 8. Phase 3 – Transmitter PA. You are well on your way – lets get some RF going! Select the following components and place them aside: a. b. c. d. e. f. g. h. L1 & 2. Ferrite ring and the piece of coated copper wire. R3. C5,6 & 7. Q2 & Heat sink. Orange wire. Green wire. BNC panel mount connector.

Firstly, solder C6 & 7 into place. Let us do L3 – a challenge to many but really not so difficult – please follow the instructions carefully as L3 forms part of the LP filter – if done incorrectly it will have a adverse effect on the output power of your transmitter! Hold the toroid ring with the red side facing you. Take the coated copper wire and place it behind the toroid with about 2 cm protruding below – see fig 2 – and hold the wire and toroid with your left index finger and thumb.

Fig. 2

Take the loose end and pass it from behind through the hole round the bottom to the back and repeat until the loose end has passed through the hole 19 times – every time the wire end passes through the hole counts for a turn thus 19 turns means you would have passed the loose end through the hole 19 times – see fig. 3.

Fig. 3


Make sure that the windings fit snug next to one another on the inside of the ring – check that there are NO overlaps – outside spacing would naturally space out at about 1mm gaps. Once you have complete L3 cut both legs to about 10mm. Take a lighter with the flame close to the tips and burn away the coating on the leg tips to about 7 mm. DO NOT burn the coatings on the wire around the toroid!! You can scrape any residue from the melted coating away with a scalpel or sharp knife. Place the two legs next to one another see fig. 4.

Fig. 4

Once L3 is complete orientate it as per your print out between C6 & 7 and solder the two legs firmly in place. Ensure that you place L3 snug against the PC board when you solder the legs. Solder the rest of the components in place as per print out. Remember that Q2 must not be pushed in more than 3-5mm from PC board. Fit the heat sink only after Q2 is firmly soldered into position by gently pushing it over the transistor casing with wire ring placed at bottom of the heat sink. Solder a piece of 3 cm of the orange wire into the orange antenna hole and a 3 cm piece of the green wire into the green antenna ground hole. Solder the orange wire to the center pin and the green wire onto the casing lug of the BNC panel connector. Back to the testing side – connect your watt meter to the BNC connector of your project – make sure your watt meter is connected to a 50 ohm dummy load. Connect battery. Turn on the receiver for zero beat on the tone. Key your transmitter by connecting the yellow and green Key wires. A strong signal at your desired tone should be evident on your receiver – check the watt meter for an output of at least 1 watt at 13V – it will be less with only 9V. If the output is too low ensure that your turns on the toroid is nicely spaced and that you have exactly 19 turns on the inner circle or 18 on the outer side. Only key the transmitter for short periods as the final transistor gets hot and might be damaged if keyed for too long. If you are using a resonant antenna – be careful not to cause interference – your signal can be heard anything up to 2000 km! Once you have your correct tone with 1 watt out then you have successfully completed the transmitter - if not use Fault Finding Procedure on page 8. Take some clear cutex (nail polish) and paint the toroid so as to have your wire windings kept in tact – you may even support toroid with hot glue from a glue gun – don’t overdo! Phase 4 – The receiver. Well done so far – let us add some ears to our project! Select the following components and set them aside:


a. b. c. d. e. f.

U1 with 8 pin IC socket. C4,8,9,10 &11. R4 & 5. D1. R14. Audio screen wire with earphone socket.

Firstly, solder the 8 pin IC socket into place – ensure that the indent on the socket holder is aligned in the same manner as shown on your print out – see fig. 6. Take R14 and cut off the left leg as viewed on the 2 pin side - see fig. 5 - and solder in place.

Cut here

Fig. 5

Proceed to fit the rest of the components. Press U1 into the socket ensuring that the indent is on same side as that of the socket – see fig. 6.


Indent Fig. 6

Clear the ends of the supplied audio wire by about 10mm. Solder the wires into the holes available – inner to point A (brown hole) and outer screen to black hole. Solder the earphone socket onto the other end – screen to outer casing and inner to the tip connection. See fig. 7.


Fig. 7

Back to the bench. Connect a low impedance high quality mono headset to the head phone socket. Set R14 with the arrow at 9 o’clock with the small screw driver – see fig 8. Connect the antenna. Connect the battery. Adjust R14 slowly until receiver audio can be heard comfortably. You might hear a hum – the receiver is very sensitive to the presence of electrical currents so


best is to operate the rig with no or little AC currents present in the near proximity. If your antenna is situated close to buildings you also might hear a hum. You might even hear the CW beacon on 7025 kHz. If you can hear band activity you have completed the receiver successfully - if not use Fault Finding Procedure on page 8. Disconnect everything and let’s continue construction.

Fig. 8

Phase 5 – Side tone generator. You are almost there….. Select the rest of components and set them aside: a. b. c. U2 and 8 pin socket. R8,9,10,11 & 15. C13,15 & 17.

Firstly, solder the 8 pin IC socket into place – ensure that the indent on the socket holder is aligned in the same manner as shown on your print out – see fig. 8. Next solder R10 in place. Proceed to fit the rest of the components. Press U2 into socket ensuring that the indent is on same side as that of the socket – see fig. 6. Last visit to the bench – connect the antenna, headphones and lastly the battery. Set R10 in the 9 o’clock position – see fig. 9. Key the transmitter by connecting the yellow wire and black Key wires. You should hear a side tone. Adjust R10 until you have the side tone to a frequency suitable for your operating environment – I found the preset at 9 o’clock to be most suitable. If you do not have side tone use the Fault Finding Procedure on page 8. Check following: a. b. c. Output 1 watt. Receiver audio level set to comfortable level. Side tone frequency as desired.

Congratulations – you have successfully completed the Supapix transceiver! Phase 6 – Fitment of Supapix into enclosure. Drill suitable holes into the supplied enclosure and place sockets as per fig. 10.




Fig. 10

Fig. 10

Cut the yellow and green wires to about 4 cm and solder to the other phone socket (socket used for the morse key) – see fig. 9. Solder the black key wire onto the key socket – see fig. 9. Twist the wires together for uncluttered finish.
Green wire

Yellow wire

Fig. 9

Ensure all appropriate wires are soldered to the phone and key sockets - do not solder power wires to the power socket yet. De-solder the green and orange antenna wires from the BNC panel connector. Fit the BNC and power sockets into holes and secure as per Fig. 10. Peel of the covering the double sided tape on the bottom of the enclosure – place PC board at the center and move the Phone and Key sockets into their prospective holes then press PC board firmly onto the double sided tape so that the PC board is fixed correctly onto enclosure floor – be careful not to bend components and allow sufficient space for the BNC and power sockets! Stick rubber feet at corners on bottom of enclosure. Cut out the decals and use small amount of Bostik smeared on the back of the decal to stick it onto the enclosure as per Fig. 10. Enjoy your new transceiver and please read the operating manual before going on air! NOTES ON NEXT PAGE


NOTE : Build your own QRP Dummy Load for this project. Use a 2 watt carbon resistor with a value as close as possible to 50 ohm and solder it into a PL-259 coax connector as in fig. 10. This little dummy load can be screwed directly into the antenna socket of your watt meter for testing the Supapix.
Solder to casing

Fig. 10

Solder to tip

Fault Finding Procedure Check correct components placed and orientated correctly on board by using the Supapix Component Colour Silk Screen document. Check correct component in the correct place – check value on PC board with value on your Supapix Component Colour document. Inspect every solder joint with a magnifying glass. Ensure battery is full and connected correctly. If all above is executed and the circuit is still not functioning you might have a component failure – proceed as follows: Components that are subject to failure most of the time are transistors and IC’s. To test a transistor use a multi-meter which is set on Diode Test or 200k ohm. De-solder and remove the transistor from the PC board. If you don’t have a transistor tester then use a normal multimeter. Check the resistance between all three legs by connecting the test leads between any two legs at a time – if a dead short is indicated the transistor is faulty – replace. If current flows both ways between any two legs (use reverse polarity from your multi-meter) – the transistor is faulty – replace. If your transistors check ok then the IC in the circuit is most probably faulty – take a small screw driver and lift it from the socket and replace. The components in the kit is factory checked but as everything that is produced in mass quantities a latent error might be present – fortunately the components selected for the kit are easily available. Contact the kit vendor should you require assistance.


Component Examples for Identification

IC 8 pin






Molded Choke

Trim Pot

Trim Capacitor

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