Lately there has been a growing number of transmitters and transceivers using Pixie-derived designs. These are interesting little bare-bones, inexpensive transceivers that have one little design quirk. The keying of the transmitter is done by directly switching the supply voltage to the final power amp transistor. This works great with a straight key or a bug -- there's a low resistance path for the several hundred milliamps of current needed to squirt a CW signal out the antenna. Unfortunately, it's too much to ask of the output transistors of most electronic keyers -- the Ultra PicoKeyer included.
So, I've gotten several emails from people who are having trouble keying their $10 transmitter with their $29 keyer... and the only real solution I have to offer has been a UKA-3+ with the heavy duty relay option! That's not really the best, most cost effective solution.
There is, however, a much easier way. Keying a Pixie clone with a UKA-3+ is like swatting flies with a Howitzer. It may work, but it's a little overkill. Since we're not talking about high voltages (hence no need for optical isolation) a simple high current MOSFET keying stage will do nicely. So I designed the Mini Keying Adapter and decided to offer it as a kit.
The Mini Keying Adapter just does one simple thing, and does it cheaply and well. Connect it to a source of DC power -- whatever you're using to power your Pixie is fine. 9V, 12V, 14V, whatever. Now connect the keyer to the IN terminals and the transmitter to the OUT terminals and start making contacts. The Mini Keying Adapter will handle up to a few amps of current, draws very little power and at 1.5" x 1.5" (38mm x 38mm) is small enough to tuck away wherever you want -- but no, you probably won't be able to squeeze it into your Ultra PicoKeyer case. I did include four mounting holes so you can screw it to some standoffs if you want.
The kit includes a quality solder-masked, silkscreened printed circuit board and all the parts you need to build the circuit. There’s a nice screw-clamp terminal block for making connections to your keyer and transmitter. A beginner can put this together in under half an hour... an experienced builder will have it done in a few minutes.
The Mini Keying Adapter also works great for controlling power to a repeater cooling fan, using one of the outputs of the ID-O-Matic. You can use this instead of an electromechanical relay.