capbuster Messages: 51 Registered: April 2010 Location: wise va. U.S.A.
Baron
Ihave a philco model 111 .Recapped all new resisters ,all good tubes , antenna coils check good . After about 15 minutes looses reception. Turn off let cool does it again. Ran a long wire antenna
picks up stations . What would make this happen ? Acts like something gets hot quits working. I watched tubes no filaments cutting out. DO NOT KNOW WHAT TO CHECK .
Thanks Capbuster.
capbuster Messages: 51 Registered: April 2010 Location: wise va. U.S.A.
Baron
Did replaced all . Every resister . Checked tubes . Didnt replace mica caps . AllREADING I DONE SAID THEIR RELIABLE . What does anyone think.
THANKS FOR REPLY Capbuster.
Wayne Parham Messages: 18791 Registered: January 2001
Illuminati (33rd Degree)
Have you replaced all the other capacitors? Are there any electrolytic or paper capacitors? Mica and ceramic capacitors are reliable, you're right, but electrolytic and paper caps are extremely unreliable and almost every old radio has them.
Also note that molded paper capacitors can look like dominoes just like some mica caps do. If a capacitor is specifically labeled "mica" then I'd be comfortable with it but if it looks like a domino, I wouldn't be.
Wayne Parham Messages: 18791 Registered: January 2001
Illuminati (33rd Degree)
I've also had those symptoms once from a bad IF transformer. In that case, the capacitor in the can was fine but the insulation had evidently broken down in a weird way. I'm not sure what caused it, because it was magnet wire, but if you measured it hot it measured very different than it did cold. I expect some slight shift, but what it had was way too much.
If it turns out this has happened to your radio too and if you can't find a replacement, check this page: