20 Meter Transceiver Kit Review I have just finished building Oak Hills Research "OHR QRP 20" CW transceiver kit and thought I would share some of my experiences with it. Manufacture's Description The OHR QRP CW transceiver is offered as a complete kit for the 20M or 40M band. Features include: superhet receiver with narrow CW crystal ladder filter, stable VFO w/RIT covering 14.00 - 14.100 Mhz on 20 M and 7.00 - 7.150 Mhz on 40 M, audio-derived AGC circuit, 2 stages of audio filtering, semi break-in keying with adjustable sidetone level, and 2 - 3 watts of RF output power. The kits are 100% complete. Included are all components, wire, hardware, connectors, jacks, etched and drilled PC board, knobs, VFO dial plate, and a punched and labeled cabinet. The transceiver measures (HWD): 2 1/4" X 6 1/4" X 6" and weighs 1 1/2 lbs. Price - $149.95 + shipping. Oak Hills Research, 20879 Madison St.,Big Rapids, MI 49307, (616) 796-0920. Catalog available. Construction The kit arrived in a well packed and padded box. All of the parts are sorted and packed in small bags. The toriods were packed with their wire and labeled. Other parts like transistors, crystals, and RF choke coils were labeled on their bags. All of the parts were new and shiny. Everything was well cushioned in "peanuts". I ordered my kit without the TEN-TEC case since I had my own case to build it into. The minimum tools that you will need to construct the kit are a soldering iron, solder, screwdriver, and pliers. Figure on about a about a week, working an hour or two a night to complete the kit. There are several toroid coils to wind and install, so this kit is geared more towards experienced kit builders. The instructions are pretty good. The parts overlays and toroid winding diagrams are a big help. Stuffing the PC board went fast. I had to refer back to the schematic to insure that a couple of the toroids were installed correctly. There are about 25 jumpers to run on the board for power and keying. The instructions also detail basic check out and alignment. The alignment can be done with just a ham band receiver, an SWR/power meter, and a dummy load. Including a scope and a receiver for 5-6 Mhz or a frequency counter will make the alignment go quicker. A ham transceiver will make setting the transmit offset a quick job too. Problems found The VFO capacitor (C5) is advertised to have a 6:1 reduction drive allowing 3 turns to cover 100 Khz or about 33 Khz/turn. The actual VFO cap supplied only required 2.5 turns to cover 100 Khz or about 40 Khz/turn. I prefer about 15 -18 Khz/turn so I substituted a 20 pf cap with a 7:1 drive with a 39 pf cap in series in place of the original VFO cap (C5). This resulted in about 18 Khz/turn and a range of 14.00 - 14.070 Mhz for my rig and I had to re-label the VFO dial plate. The 10.7 Mhz coils (L2,L3) used in the receiver front end will not tune properly with the internal capacitors left in. Remove the caps before installing the coils, the instructions did not address this. RFC2 is not labeled on the parts overlay. I installed it according to the schematic. Be careful when installing the parts on the PC board to verify that the correct parts are in the right holes. I even marked off each part from the parts list as it was installed and still got a couple of resistors confused. Comments I liked the quality of the PC board and the parts. The PC board is drilled and plated and the layout is compact but not extremely dense. All of the parts appear brand new and high quality. Alignment was fairly quick, set the VFO, peak the IF, peak the front end and start listening to signals. On transmit, peak two capacitors, set the transmit offset, set the sidetone level and make some contacts. I called Oak Hills Research to discuss the problems that I had. They were extremely nice and helpful. They sent me a 10:1 vernier drive (free) to try on the VFO cap, offered to replace the original VFO cap (free - after I broke it) and promised to change the instructions for L2,L3. Enhancements I added a "S" meter circuit to the receiver, a LED transmit indicator, and a homebrew SWR bridge to the transmitter (OHR has a kit too). I packaged the rig in a little instrument box that I had gotten at the Shelby hamfest for $.50 (those hamfest goodies actually got used). Conclusion All in all this has been an enjoyable project and I have a nice, small 20 meter rig that performs well. Tuning is smooth from 14.00 - 14.070 Mhz. The receiver performs well under non-contest band conditions. The AGC does pop on strong signals. The switchable audio filter works well. At 13.38 vdc, my rig runs 3.3 watts RF out. My first QSO was with Norway his rst - 449, mine - 339. Signals were weak in both directions and the receiver pulled him out of the noise pretty well. Now I'm kind of waiting for a 17 meter version or I may dig into this one in a few months and see if it can be modified to 17 meters. Meanwhile I'll be on 20 meters, QRP. 73 - Dave, N4ELM -- END -- -- Dave Redfearn via cmhGate - Net 226 fido<=>uucp gateway Col, OH UUCP: ...!bluemoon!cmhgate!151!121.0!Dave.Redfearn INET: Dave.Redfearn@p0.f121.n151.z1.FIDONET.ORG