Rockmite 40m fixed and working

I unearthed my 40m Rockmite that I built years ago for a QRP session today.

First problem I noticed was that it wouldn't work with a paddle, only a straight key. The second was that I only had audio from one of the ear buds.

I thought this was a dirty connection so tried cleaning the contacts – no good. Turned out to be a poor joint on the back of the 3.5mm socket. In fact, I'm amazed it ever worked at all!

Now on to the problem with the paddle. The Rockmite will default to straight key mode if you fire it up with a straight key attached and that should have been the clue.

Pulling the front panel off I could see that the quarter inch socket for the Morse key/paddle had rotated and was shorting out one of the contacts that would normally go to the middle of the plug.

The Reverse Beacon Network proves you are getting out!

Once that was sorted the keyer burst into life. Connecting the Rockmite up to a W5GI dipole and sending a few CQs showed that I was being picked up all over Europe with about 0.75W (I normally send “1W” as it is easier).

Anyway I answered a CQ call from DF1UQ QRP he came back to me – wonder of wonders. I gave him 559 and he gave me 529. Turned out Klaus was running 4W. There was a lot of QRM from other stations in the late afternoon so I kept it fairly short, but the Rockmite works again.

I still think the sidetone is a bit harsh, but there is a mod for that if I was that bothered. You'll also see that I have a knob on the front that says VXO. This was an attempt to connect a variable capacitor in line with the crystal to allow me to move the frequency a little. All I got was hum so I abandoned that – one day I'll have another go.

I still think the 40m Rockmite has an amazing receiver for its size and price. The newer ones from Kanga UK/QRPMe are even better. It is definitely better than the Foxx-3, although that is self-contained. Both nice QRP projects to build though.

I'm trying to clear the decks of QRP projects/repairs so that I can concentrate on building my Elecraft K1 kit that was a Christmas present in 2004 – about time it was built I think!

Update 31/12/15
Just replaced C8 with a 0.01uF capacitor and that has quietened down the sidetone volume a little. Also put a 6.8mH choke in line with the crystal and small polyvaricon and am getting about 2.5kHz of swing around 7.030MHz which makes it a little more versatile. This was at the end of the crystal nearest Q2.