I’ve become more discriminating about sound quality, and when I demonstrate radios for visitors they often ask, “What’s that hum?” So, I’m going back to four or five different sets to tackle the hum.
First question is, “What’s that hum?” 60-cycle or 120-cycle? I’ve tried to compare it with audio samples online, but I can’t trust my ears. Here are links to samples of hums from three of my radios. They all sound the same to me.
https://flic.kr/p/RP4HK9
https://flic.kr/p/RD4AT9
https://flic.kr/p/QCGqyn
This is the filter block for a 1931 Airline 62-141. I restored it to the original specs and configuration. An 8-mfd electrolytic as shown here. The filter block was untouched, and the schematic shows how it was wired. But I’m not sure about that blue disconnection--it was in some, but not all, of my notes on the restoration.
Thanks for looking. If I can get this set fixed, then I’ll move on to the others.
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