[glyphmon]

A couple more data points for the night.

I did swap 6A8 tubes between radios again (as Arran suggested) and tested the Philco playing, as well as the RCA.  Had both playing side by side for a portion and it was actually quite beautiful sounding.  In fact, I think the Philco sounded better with the 6A8 than its own 6A8GT, but it still has some other lingering audio issues, I think in the output section, but that's not for this thread.

I will still pick up a 6A8 and a 6K7 to have for further testing, just to finally rule out the tubes as the issue, and in case I find a need for them in the future.

I have to correct a previous statement of mine - the RCA is, in fact, able to pick up the AM transmitter without the antenna connected.  (I think the band switch is a little squirrelly and I may have mistaken the silence in the past for the antenna being disconnected when the problem was really that the band switch was not making proper contact.)  In fact, while perhaps not unexpected, the radio seems to have appreciably less hum without an antenna.

In either case, I made a recording of the radio playing Sombr - Back to Friends streamed through the AM transmitter.  This is with the volume maybe halfway up.  My point to this recording was to get a sense from you fine folks if the sensitivity of the radio seems to be impaired if it can perform this well without an antenna even connected.  I'm sure with it connected, the volume wouldn't need to be even this high.

One note regarding the test song, I think it is forgiving when it comes to reproduction on these older radios.

My recording: https://youtu.be/qLV1rEmJRaM
Song used, for comparison: https://www.youtube.com/watch?v=Qvf04YdivnM

Light is off for the test, even though it doesn't make much interference.  The dial glass just looks much better this way.

Best wishes,
Roy