QRPKits DC20A Manual Download Page 1

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2/14/2007

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The DCxxA Family of Transceivers

High Performance Direct Conversion Transceivers for 40, 30 and 20 Meters

DC30A Transceiver

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

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Summary of Contents for DC20A

Page 1: ...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 builder...

Page 2: ...ard will be done in several groups You may find it convenient to separate the parts for each of the groups as shown in the parts lists for each group You can smoke test most of these groups when finis...

Page 3: ...ed Not used C13 100 uF 16V ALUM R14 Skipped Not used C14 Skipped Not used R15 100 OHMS C15 330 p Mono or Disk R16 100 K C16 Skipped Not used R17 15 K C17 001 uF Mono or Disk R18 10 ohms C18 001 uF Mon...

Page 4: ...ALUM C36 001 u Mono or Disk C37 1 u Mono C38 001 u Mono or Disk C39 001 u Mono or Disk C40 01 u Mono C41 Band specific See page 5 Mono or Disk C0G Semiconductors X1 crystal U1 NJM4556AD High current o...

Page 5: ...T37 2 red 35T Pri 5T Sec 24 Red 6 Grn T2 28 Red Green FT37 43 6T Bifilar 10 Red 10 Grn T3 28 Red Green BN2402 43 5T Pri 1T Sec 5 Red 2 Grn 30 Meters Wire Core Turns Wire Length L1 Not Used L2 28 Red T...

Page 6: ...2 14 2007 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...

Page 7: ...three number group which matches the value your looking for 331 for 330 pF 104 for 1 uF 681for the 680 pF cap and so on IC pin 1 The outline on the board for the ICs has a V notch on one end This indi...

Page 8: ...N BLK ORN R3 1 MEG BRN BLK GRN C4 1 uF 104 Mono R4 1 K BRN BLK RED C11 1 uF 104 Mono R5 1 K BRN BLK RED C12 1 uF 104 Mono R7 1 K BRN BLK RED C20 1 uF 104 Mono R10 1 5 K BRN GRN RED C25 1 uF 104 Mono R...

Page 9: ...marked V Connect the negative lead to the hole marked GND You can tack these to the bottom of the board so they are easy to remove during further assembly Apply power to the board Using a voltmeter v...

Page 10: ...ngle layer Trim back the leads to about 1 4 and tin Tinning can be done with a HOT soldering iron It helps to have a blob of solder on the tip when you do this Start at the wire end and move back towa...

Page 11: ...h 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: ...ear the board s crystal oscillator Click and hold closed the switch until you hear the letter T in the headphones The keyer is now in Tune mode Tapping the DASH paddle will put the rig into transmit m...

Page 13: ...red and green wires on one side of the core so that both ends of the red and green wires are opposite each other on the core as shown in the diagram above Now trim back the leads and tin them Insert t...

Page 14: ...use a scope if it has enough band width or use a simple diode detector and volt meter Connect up an antenna jack if not already done plug in headphones paddle and power leads Turn on power to the rig...

Page 15: ...is possible to damage them though The 2N7000 can be damaged by static due to improper handling and ICs can be damaged if they are installed backwards Some DC voltage levels are shown on the schematic...

Page 16: ...keyer functions speed tune mode and iambic A B selection Clicking and holding closed the switch for various lengths of time access these functions Changing Code Speed Keying speed can be selected from...

Page 17: ...ring is provided the filter isn t as narrow as a Q of 8 would imply when strong signals are present The output of this filter drives the headphones A 10 ohm resistor helps keeping the amplifier stable...

Page 18: ...2 14 2007 Page 18...

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