Thursday, August 16, 2012

Rock-Mite 20 Completed

The new 2N3053 transistor complete with heat sink and the pack of 2.2 ohm resistors arrived so last night I managed to complete the build of the RM-20.

The smoke test worked with no problems and I was soon listening on 20 meters to see what was about. I hooked up the RM to a dummy load and gave a tap on the key, all seemed to be working OK and I was keen to see what output I was getting with the new transistor upgrade.

First impressions look like about 800mw with my 9v battery so hopefully with a 12v power supply I may well get over a watt.

I also changed the zener diode on D5 as suggested by Colin M0CGH to give a wider RX/TX at around 700Hz.

With the upgrade of the transistor I installed some sockets in to the PCB so that if need be I can chop and change transistor/resistor value to see what matches best for getting maximum output.

The sockets also raise up the transistor (which is considerably larger than the original 2N2222A) above the surrounding bits and bods so that I can fit the heat sink and it doesn't get in the way of anything else.
The heat sink maybe be a bit over the top but the enclosure is quite large so there is no issue when fitting.

Can't wait now to have my first QSO, although I'll doubt I'll beat Colin's distance who emailed me to say he had got the States on one of his first calls, a small distance of some 3000 miles!

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