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Old 06-25-2013, 04:57 PM
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VintagePC VintagePC is offline
Tube bug got me 05/2010
 
Join Date: May 2010
Posts: 535
First powerup results look promising. Nothing caught fire or exploded, so we're off to a good start

No AM reception by the looks of it. I get quite a bit of hum from the speaker at either end of the dial, and it quiets down in the middle. Hum disappears on other inputs (SW/Phono) so it's probably not a power supply filtering problem.

I can pick up some stuff in shortwave mode though, so it would seem that the amplifier region is working and we can narrow it down to the circuit region(s) involved in AM.

Will take a poke around inside and see what I can find.

[Edit: Nothing interesting. All the SW/BC switch does is switch out the coils and trim caps; those aren't shorted or open circuit (as appropriate) as far as I can tell. Logic tells me I'm now either facing a poorly performing tube or the AM alignment is way out of whack. Time to scrounge up a signal generator, I think...]

Last edited by VintagePC; 06-25-2013 at 05:48 PM.
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