Monthly Archives: June 2022

On on-going tale of two radios, Part 3

By Gordon Bubb G7KNS

To recap, now both sets are receiving with the same sensitivity. My set does not transmit AM and the ex-Kuwait set has a bad intercom output transformer. Both sets have issues with the in-built crystal calibration system.

As my set does transmit PM and CW there is obviously nothing fundamentally wrong so it is time to think about switch contacts and wiring faults.  Ooh look! Our friend Mr. Bodger has been at this set as well, he gets around doesn’t he?

And again…

I also found the two wires going to the tuning meter were disconnected. Maybe this is why the calibration system does not work. Then I saw this…

I think our friend has changed the meter but not finished the job. And why butcher the edge of the mounting plate? We won’t ask about the missing mounting studs; the two on the other side hold the plate in well enough. As to why he cut the co-ax instead of unsoldering it, who knows? The end is only an inch away from the cut.

So repair the co-ax, refit the earth tag and reconnect the meter. We now have AM transmit. Result! And there are signs of life on the meter as well now.

The final stage of tuning shows a nice swing of the meter from left FSD (full scale deflection) to right which is correct, it is tuned for centre zero. But the first two stages do not. They use a 100 kc/s (kilocycles per second, this radio predates kilohertz) crystal and according to my oscilloscope it is not oscillating. Swap the module with the one from the other set and all is now hunky dory. One set now fully operational.

Anyone got a spare 100 khz crystal?