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The DCxxA Family of Transceivers
High Performance Direct Conversion Transceivers for 40, 30 and 20 Meters
Evolution of the popular DC40 to the DCxxA series on 40, 30 and 20 Meters
Join Yahoo's DC40 Kits group for support from other builders and information about operation and modifications.
Be sure to include your call and real name with your request
2/14/2007
DC30A Transceiver
A KD1JV "Melt Solder" Design
Distributed by Hendricks QRP Kits
www.qrpkits.com
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http://groups.yahoo.com/group/dc40kits/
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Table of Contents
Related Manuals for QRPKits DC40A
Summary of Contents for QRPKits DC40A
- Page 1 Evolution of the popular DC40 to the DCxxA series on 40, 30 and 20 Meters A KD1JV “Melt Solder” Design Distributed by Hendricks QRP Kits www.qrpkits.com Join Yahoo’s DC40 Kits group for support from other builders and information about operation and modifications. Be sure to include your call and real name with your request http://groups.yahoo.com/group/dc40kits/...
- Page 2 The DCxxA A Direct Conversion, Fixed-Frequency Transceiver for 40, 30 and 20 Meters The DCxx is a moderately complex rig, which yields excellent performance, yet is small enough to fit into an Altoids tin. The receiver features nearly complete immunity to AM SWBC interference and can be run on an AC supply with little hum pickup or AM BC interference common to most DC receiver designs.
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Page 3: Parts List
Parts list RESISTOR VALUE TYPE Caps Value Type 1 meg 5% 1/4w CF .012 uF FILM 360 K 1.00% C2 330 p Mono or Disk 1 meg .1 uF Mono .1 uF Mono .012 uF FILM 10 OHMS Skipped Not used Band specific See page 5 Mono or Disk C0G 1 MEG 40 p... - Page 4 Band specific See page 5 Mono or Disk C0G Band Specific See page 5 Band specific See page 5 Mono or Disk C0G See page 13 100 p Mono or Disk C0G See page 11 Band specific See page 5 Mono or Disk L2/3 Band Specific See page 5 YEL TRIMMER...
- Page 5 Band specific values Location Type C0G Mono or Disk 100p C0G Mono or Disk Not used C0G Mono or Disk 330p 220p 150p C0G Mono 680p 560p 330p C0G Mono 330p 220p 150p C0G Mono C0G Mono Not used 100p C0G Mono or Disk Toroid Winding Charts 40 Meters...
- Page 6 Examples of Component Types Note variations in shape, size and color of similar component types. Some component leads will need to be reshaped to fit the holes in the PCB. 2/14/2007 Page - 6...
- Page 7 Tips and Info for First Time Builders Installing parts: You can insert several parts at a time onto the board. Parts should be pressed flush to the top of the board. The exception are the transistors which should stand off the board by about 1/8” due to their three legged nature. Once you insert the part, kink one of the leads over slightly to keep it from falling out of the board when you flip the board over to solder.
- Page 8 Group 1: Power, Audio and Keyer stages. NOTES: Do not install the ICs into the sockets until after the initial smoke test. R11 and R2 are 1% resistors, so have four color bands for the value, instead of three for the 5% resistors. They also may have a blue body color, instead of tan. On C9, C13 and C22 the long lead is + and the negative lead side is marked with a black strip on the cap body.
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Page 9: Smoke Test
Connection of jumper from U4-3(output) to U1-3 required for missing 5V buss PCB trace. There was a mistake made when the board was laid out and the connection shown below was missed. The kit builder needs to solder a jumper in place as shown. A solid insulated wire, 26 or 28 ga, should be used for the connection. - Page 10 Group 2: Receiver front end: location value markings √ 10 ohms BRN/BLK/BLK 22 K RED/RED/ORG 100 K BRN/BLK/YEL 470 ohms YEL/VIO/BRN .1 uF 104 Mono .1 uF 104 Mono .1 uF 104 Mono .001 uF 102 Mono or Disk .001 uF 102 Mono or Disk .001 uF 102 Mono or Disk...
- Page 11 T3: This coil is wound on a small binocular core. One turn is a pass through both holes. The secondary is a single turn, one hairpin passed through both holes. Insert this wire first. You might want to mark the secondary end with a dot of nail polish. Then wind the primary, 5 turns, starting from the other side of the core from which the secondary exits.
- Page 12 104 Mono want to install a SIPP socket at location X1. An example of preparation and installation of the SIPP socket can be found at .01 uF 103 Mono http://www.qrpkits.com/buildertip03.html. Yellow trimmer Smoke Test: 4.7 uF/16V Alum Electro Connect a paddle and headphones to the board. Connect a test lead antenna to your “big rig”...
- Page 13 Group 4: Low pass filter location value markings √ C24 (All) .1 uF 104 Mono T2 (All) See notes 68 p 101 Mono 330 p 331 Mono 680 p 681 Mono When winding the toroid cores, remember that one pass of wire through the center of the core is one turn.
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Page 14: Final Tests
Final Tests Your new rig is now just about ready to use. All we need to do now is peak the receiver trimmer and check for transmitter power output. For peaking the receiver trimmer, on 30 or 40 you can probably just connect an antenna up and peak the trimmer for best band noise or signal if someone is transmitting near the crystal frequency. -
Page 15: Troubleshooting Guide
Trouble Shooting Guide The most common reason a kit does not work right is due to soldering issues. Therefore, the first thing to look for if something doesn't work is the solder connections. Look for solder splashes that might be shorting two pads together and shouldn't be connected. -
Page 16: Keyer Operation
Making Contacts with a Fixed-Frequency — Direct-Conversion Rig Making contacts with this type of rig can be a challenge, but its not impossible. In fact, it can be a lot of fun and satisfying. Just remember, it’s easier to have stations come to you. The reason for this is because the receiver will hear stations on both sidebands, you don't know which side band your hearing them on. -
Page 17: How It Works
How it works Receiver Signals from the antenna first travel through the transmitters low pass filter. It then passes through a T/R QSK switch comprised of two, 2N7000 mosfets. During receive, Q9 is turned on and Q8 is turned off. This allows the signal to pass into the link coupling into the front end tuned circuit. - Page 18 2/14/2007 Page - 18...