[Guest]

An early model Philco 90 (45 P-P output) is on the bench.
1) The voltage readings I'm getting, even allowing for a modern
meter, don't make sense. Is the chassis supposed to be the
common point to take the readings?
2) The radio is sensitive enough, but there's a peculiar distortion
that shows up on some music, especially that with a strong bass
line. It's really evident on something with a Hammond organ background.
I'd describe it as a hum modulation but it's lower than 60 Hz, more
like a gargling effect. Straight spoken voice sounds great. Is this
intermodulation distortion, and am I expecting too much of 1931
technology?
Cheers,
Nelson