I can't claim to have the best collection of small QRP (low power) ham rigs, but I have built a few. I thought I would share some of them with you.
This is a nice little rig that was relatively easy to build and tune. The manual is easy to follow and is very readable. The rig is fairly simple, so the schematic is easy to read. The controls are simple, just a tune control and a gain control. The receiver is a superhet with a 3 crystal IF filter. There is no agc. There is no speaker, you must use a headset. The frequency is VFO controlled but it seems very stable. Note that this kit does not come with a case. Small Wonder Labs used to sell a case kit, but it has been discontinued. I bought the case kit.
The only problem I had when I built this kit was that the VFO would not tune as high in the band as I wanted. So I removed one turn from the VFO coil (a toroid) and that got me about a 34 KHz tuning range from 7.015 to 7.049 MHz.
I did have another problem with this rig, when I took a lightning hit on my 80 meter antenna. This rig was connected to a small dummy load at the time, I thought nothing would we wrong with it. When I tested it, it transmitted all the time. Turned out a diode (D5) in the keying circuit had shorted.
My first QSO was with WB4DCW in Jasper, TN. I have 149 QSOs in the log from this rig. They stretch from California to the Balearic Islands near Spain. I've used it on field day off batteries (class 1E) and in CW Sweepstakes.
This rig is more complex and more difficult to build. It also has a manual that is more difficult to read (looks like a photocopy of a photocopy on some pages) and the schematics are particularly difficult to read. The receiver is a superhet with a 4 crystal IF filter and it has an AGC (Automatic Gain Control) and RIT (Receiver incremental tuning). The VFO tuning is very touchy and it seems like the calibration changes every time I check it. A very nice case is included in the kit price.
I had a number of problems building the rig. I have 12 notes about assembly problems and I had many of the problems noted in the N5ESE web page. In particular the transmit parasitic oscillation was a real problem. I did not observe this when the transmitter was running into a 50 Ohm dummy load. It only happened into my antenna. N5ESE's fix did not work, but pushing the output RF transformer (T1) down towards the output filter toroids worked for me. Your milage may vary. Remember to check the output of any QRP kit you build to make sure it looks clean, especially into an antenna.
I don't use this rig as much as the SW-40+, mainly because of the loud thump in the receive audio when you press the key down. N5ESE has a fix for that, I need to try it. Other than that the receiver performance is good. Transmitter output is a bit lower than I expected. I have worked 45 QSOs with this rig, most of them in the 2005 CW Sweepstakes.
page last modified July 4, 2006