Repairing an Astatic D-104 microphone

I got this mic at a local hamfest with the intention of putting it on the Central Electronics 10B. The seller said the mic was good but that the amplifier in the base was “disabled.” This is perfect for my use, because I’d rather just use a straight Hi-Z element and use the preamp inside the 10B. Of course, we don’t know what we’re getting into until until we open it up and find out what “disabled” really entails….

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Repairing a Heathkit PS-4 Power Supply

The PS-4 is a variable high-voltage bench supply that was manufactured starting around 1960. It is regulated up to 400 VDC at 100 mA, and it also has a separate low-current negative output from 0-100V in case you like make a manual curve tracer or whatever, as well as a 6.3V AC output for lighting up filaments. It appears to be electrically identical to the Heathkit IP-32 supply, but I don’t have one to compare it to. I regularly use this one as a steady voltage supply for my early one-tube oscillators like this one since the regulated voltage tends to keep the frequency steady. However, it took a little work to get it there, and I figure I might as well write about it in case it help (or just entertains) anyone looking to do the same.

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Crystals for the Central Electronics 10B

Now that the 10B is alive again after what was probably several decades I figured it was time to make some crystals for it the old fashioned way. Yes, I know what a VFO is, but that is not the point. I’m a sucker for the lost art of quartz crystals. There’s so much mystery and old wives tales around that that it has become some sort of dark art. In my limited experience its not magic, so long as you know your materials and keep in mind the laws of physics, and obey them.

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