I'm working on a Crosley 517 that I can't put my finger on the problem. I've changed capacitors, checked the tubes (except the 6Q7 my Heathkit doesn't list) and traced all the wiring to the schematic (it had some modifications along the way that I corrected). I tune it to a strong local station and I get garbled audio. You can almost understand the voices, but not quite. Sort of like over modulation. Where might the problem be?

: I'm working on a Crosley 517 that I can't put my finger on the problem. I've changed capacitors, checked the tubes (except the 6Q7 my Heathkit doesn't list) and traced all the wiring to the schematic (it had some modifications along the way that I corrected). I tune it to a strong local station and I get garbled audio. You can almost understand the voices, but not quite. Sort of like over modulation. Where might the problem be?

Kevin

If the distortion is only on strong stations the problem is lack of AVC voltage. From the volume control area the radio should generate a negative voltage on strong stations which cuts back the gain on the IF amplifier and RF stage. In your radio the AVC voltage starts with a 3 meg off the volume control and goes to the grid circuit of 6U7 and 6A8 tubes. The schematic shows a .02 cap to ground. The resistor could be open, cap shorted or even bad tube. Since you changed caps I would check for an open resistor. Any value from 1meg to 3.3meg will work.
Norm

: I'm working on a Crosley 517 that I can't put my finger on the problem. I've changed capacitors, checked the tubes (except the 6Q7 my Heathkit doesn't list) and traced all the wiring to the schematic (it had some modifications along the way that I corrected). I tune it to a strong local station and I get garbled audio. You can almost understand the voices, but not quite. Sort of like over modulation. Where might the problem be?

Hi Kevin,
If your tube tester has 6B6 tubes listed their
setting should test 6Q7's OK, at least to tell if
they're working or not. They've very similar
characteristics and the same pin connections.
If Norms suggestions don't work try checking all the
tube voltages against a schematic if you have one or at
least see if they're about what seems reasonable. It
could be something like a faulty tuned circuit (open IF
transformer or capacitor) but we're only guessing, see
if you can measure anything unusual. Your fault
description wasn't clear whether the set worked with a
weak signal or only worked at all but distorted with a
very strong signal.
Good luck, Don.

: I'm working on a Crosley 517 that I can't put my finger on the problem. I've changed capacitors, checked the tubes (except the 6Q7 my Heathkit doesn't list) and traced all the wiring to the schematic (it had some modifications along the way that I corrected). I tune it to a strong local station and I get garbled audio. You can almost understand the voices, but not quite. Sort of like over modulation. Where might the problem be?

I was thinking along the AVC route as well,
but you might also check for a problem with
resistor in the cathode circuit of the audio
tubes (don't know what ones 517 takes) or a
defective capacitor in the cathode bypass circuits,
even though you replaced them. I have installed "new"
capacitors that turned out to be dead shorts! Good luck
from another Crosley admirer!