[R-390] audio deck saga *more*

[wli]

So set up the receiver for a signal-noise gain test as outlined by Roger R. Set IF gain so the diode load was -7vdc with 150uV at my particular IF Xtal frequency injected into J513. Turnng off the audio modulation on the URM 25F I saw 0.010 VAC (-38dB) across a 600 ohm local audio load resistor. Turning on the 400cps at 30% modulation raised the reading to 2.2VAC (+9dB). This calculates to a difference of 47dB. I kept flipping the URM back and forth not believing what I was seeing. 

Too good to be true I *ses*..... so what did I do wrong? Does this make any sense? Maybe I have to go back to radio school....

W. Li
Mercer Island, WA