Zenith K731, G730, & two unknown model AM/FM radios

[radiotvnut]

Here's 4 Zenith AM/FM radios that I got from the same lady. The one on the far left is a K731. This one plays but the speaker rattles and it needs it's controls cleaned. Next is the G730 and the FM is dead. Next is a plastic version that looks like the same layout as the G730. This works but needs a new speaker and the controls cleaned. The last one is an older one. The FM is dead on this one. Zenith AM/FM radios are my favorite ones so I was very proud to find 4 at the same time.

[toxcrusadr]

If you can get past the silver migration in the transformer cans. Ugh. I have a half-restored Bakelite heavyweight (can't remember the model but it's got 9 tubes or so, early 50s, AM/FM). It's been half restored for years on the bench, I screwed something up trying to replace those built in caps with separate ones.

[Old1625]

Originally Posted by toxcrusadr

If you can get past the silver migration in the transformer cans. Ugh. I have a half-restored Bakelite heavyweight (can't remember the model but it's got 9 tubes or so, early 50s, AM/FM). It's been half restored for years on the bench, I screwed something up trying to replace those built in caps with separate ones.

If you're talking about the ones underneath that bakelite disc at the bottom of the can I hear you. I never liked those either. But subbing them out for conventional ceramic disc I remember was a real chore.

[Old1625]

Nice score on those 4 radios BTW.

[Tom Bavis]

I have #2 and 3 - #3 is a C720 or 725? # 4 is an H723 or 724.

I probably have the Sams folders for all of them...

[Chad Hauris]

I would look for weak 12AT7/12DT8 FM convertor tube on those with no FM, if the AM is completely functional...usually if it's the IF can capacitor problem it will show up as problematic AM reception too.
If the radio was used mostly on AM I think this would cause the unused FM convertor tube to degrade due to a lack of plate voltage.

[skippy_ps]

Originally Posted by Chad Hauris

I would look for weak 12AT7/12DT8 FM convertor tube on those with no FM, if the AM is completely functional...usually if it's the IF can capacitor problem it will show up as problematic AM reception too.
If the radio was used mostly on AM I think this would cause the unused FM convertor tube to degrade due to a lack of plate voltage.

Yep, I had nearly dead FM on my K731 and a new 12DT8 brought it back to life (thanks to Terry DeWick for his guidance). Playing every day now with a working electrostatic tweeter. Some nice looking radios, rtvn.

Murray