[glyphmon]

MrFixr55,

Thanks for the suggestions.  I'll resume troubleshooting with pulling one tube or the other Monday or soon thereafter.  Having gotten this close, I want to continue advancing.

Injected audio was quite good actually, but laptop -> bluetooth -> AM transmitter was even better, to be honest.  Perhaps combining the two channels as you described will make a clear winner.  I'm thinking given the amount of space in this chassis, especially compared to the 37-620, that this would be a good candidate for a permanent, switched aux input, but that's a discussion for later.  A little further up I shared a link to a video I uploaded to Youtube of the radio being streamed some big band videos via the path above.  Here it is again for convenience, if you're curious: https://youtu.be/eshJNXOUGow - there's also a Florence and the Machine test as well: https://youtu.be/KaPDfk3H9Ic

Re: pin 6 on 6K7, agreed, there appears to be no connection, however the diagram in the 1937 service notes show a voltage from that pin to the chassis of -3 and mine reads -3.97.  This pin connects to pin 3 on the 6H6 so it makes sense to me that the values are essentially the same, even if I'm not sure why we're testing the pin in the first place.

I was able to receive (not super clearly, but well enough for my Romanian wife to listen and understand, and record to share with her parents) the Romanian-language transmission from Radio Romania International on 9730 kHz out of Tiganesti, near the Bulgarian border.  This was the thought that had me investigate my grandfather's 37-620 in the first place, so it was rewarding to have been successful on that front, even with a system not yet 100%, let alone aligned.

I am taking the responses as much as possible in the same way that I do feedback from my writing group - that I know what I know (and also have a pretty good idea of what I don't yet know/understand) and that what people are saying is what I need to hear to get better.  I am also a person whose tone can be misinterpreted across written text, so I try to keep ego out of it, and write as clearly as possible to avoid miscommunications.  I'm not always successful, but I do try.

I remain grateful for everyone's contributions.  In a perfect world, with each successive project the "question to completion" ratio will hopefully decrease so that I can eventually dazzle everyone with my brilliance.  A guy can dream.

Best wishes,
Roy