Small Wonder Labs PSK-20
20M QRP PSK Transceiver Kit

Small Wonder Labs PSK-20

Building the Kit
I won this rig as a prize at the Ft. Tuthill, AZ QRP design contest in 2002 and for unknown reasons, took quite a while to get it from Small Wonder Labs. Lo and behold though, it appeared and I eagerly began construction. First order of business was to do a parts inventory, and discovered the audio jacks and a transistor was missing. An email to S.W.L. and a few days later the parts appeared in the mail. Meanwhile I had started construction, prepared to go back to those steps that involved the missing parts. Construction was very straightforward, between the text and illustrations there wasn't any doubt which parts went where. I kept a log of construction time and progress, and in the end it took 5.75 hours to assemble, and about half an hour to align and install in the enclosure.

The PSK-20 worked right out of the chute. Alignment is simple and clearly documented. I was somewhat suprised to see and start decoding PSK signals on the workbench with nothing more than a 12" alligator clip jumper connected to the antenna jack. I measured the MDS at just under a microvolt. Transmit power is spot on at 3 watts using the manual's level setting procedure and tune feature of the DigiPan PSK software. After some quick tests between the PSK-20 and my main PSK station, I put the PSK-20 on the air using a Butternut HF6V vertical antenna. As usual, there were plenty of signals to monitor on 14.070 and up. I worked a number of stations within minutes of hooking it up until well into the evening when the band finally closed. Most stations were worked on the first call.

Completed Kit
PSK-20 Kit, unassembled
The completed kit, with signals
on the waterfall.

Praise & Criticism
My only real criticism of the whole kit building process was the lack of any testing as the assembly of the different sections was completed. The assembly instructions are grouped into the different stages of the transceiver (DC power, RX, TX, AF, etc) but at the end of each stage there weren't even the most rudimentary of tests to verify assembly was done correctly. I would feel much more comfortable at first time power-up if I had checked some of these stages first, even if they were nothing more than ohmmeter tests (which I did). I would also like to see some LED's for 12VDC power and TX, and a power switch. I will likely add these on my own. Since the alignment instructions refer to a specific version of DigiPan software, it would've been nice to have included it on a floppy or CD (copyright probably prevents that though). The version of DigiPan referred to in the manual has been superceded, though the current one is close enough to follow the same instructions. The PCB is a quality double sided design with plated through holes, silkscreen and solder mask. Components were first quality, and the completed unit fit perfectly in the supplied housing. The assembly and tuning instructions were in a nice booklet and printed in color. The alignment procedure is deceptively simple, requiring nothing in the way of specialized test equipment. It is important that it is aligned properly, if not your carrier and opposite sideband suppression won't work right. Overall I thought the instructions were good, and the design well thought out and implemented. I would recommend this kit to anyone interested in portable PSK.

Here are some basic measurements I made on this unit after construction and alignment:
(Tested and aligned with Rhode and Swartz sig gen, Agilent spectrum analyzer
and Agilent arb waveform gen, 12.50VDC power input.)

I've been looking forward to having a portable PSK setup for some time, and this kit is just the ticket. All I need is my laptop, the PSK-20, wire antenna, a gel cell, and I'm ready to go. The PSK-20 is a well designed kit using quality components and I am glad to add it to my stable of QRP gear.

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