Posts: 825
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Joined: Aug 2012
City: The Villages
State, Province, Country: Florida
Hi Guys,
Well, summer is over so it's time to get back to the winter hobby.
I'm working on a Zenith R723 AM/FM. All caps have been replaced resistors check and Th IF alignment is done. My problem is that when doing the RF alignment, when one part of the dial lines up with the right freq., the rest of the dial is off. If I set adjust it so 103MHz is correct on the dial. then 95 comes in at 92 on the dial. All freq above 103 line up but anything below is off.
Any ideas?
Thanks,
Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org
Posts: 4,442
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Joined: Jun 2011
City: Boston
State, Province, Country: Massachusetts
WEFM was 99.5 and is denoted by a dot near the 100 marker on most every Zenith AM/FM set I have ever seen. You should see a dot right near the 100 on the outer band of stations which is FM on this set. Zenith had sort of an experimental station running well before FM was popular. I do not know if that helps a whit.
I have one of those sets and I never really thought too much about the lining up on the dial. It does well enough I can tune it. As I recall it has no AFC and can drift a bit.
If you get nowhere with it you can pm me and I may have a resource for you.
Good luck.
Paul
Tubetalk1
Posts: 7,301
Threads: 269
Joined: Dec 2009
City: Roslyn Pa
L-3 (fm osc coil) has a bit too much inductance. If you can stretch it out bit will lower it's inductance. Once you get the low end close then use the trimmer to set the high end. On a lot of these sets it's tough to get them dead on across the whole band but should be much better than what you've got.
GL
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
Posts: 640
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City: Gap Mills Wv 24941
looks like i have tubes you may want as spares.
Posts: 2,037
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Joined: Jun 2010
City: Dover, OH
I've rarely had a tube AM-FM radio that truely lined up on the FM band. If they work well and can get the full range of stations, I just live with it myself. I've had a few that were very close, only to have them go out of alignment by simply replacing a weak 12AT7 with a new one.
I am wondering if any tube sets were really dead on alignment with the dial on FM? It seems the advent of solid state FM tuning made that easier to attain and keep up.
No matter where you go, there you are.
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