Hallicrafters S-20

Great find, John.
 Most old micas are leaky after all these years from the paper in them failing because it was acid paper.
 I just replace them all with the new epoxy dipped micas & don't have to worry about them anymore.

Congrats on finding the bad mica? capacitor. The Hallicrafters S-20 uses the large, old style IF cans with (2) mica trimmers. No compression silver mica caps. Although I have had IF and BFO coils go bad from internal corrosion. Watch out for coils wound on wooden dowel rods. They are likely to have absorbed moisture over the years. A radio servicing book I studied from advocated boiling the coils in bee's wax to drive out any moisture in the windings.
73, Rod

THANKS all coils good. Problem was a leaking 100 mmfd capacitor in coil area. Working ok now.

Not knowing your experience level, but with the band switch in position [You must be registered and logged in to see this link.] you should be able to ohm out the coil windings. There are more than 1 as the schematic shows. At least a continuity test will let you know if a coil is open.

If you have a meter type ESR meter it will show very small variations in the ohms for the windings, or if you have a Leak Seeker. Both can act as milliohm meters. (The Leak Seeker is so sensitive it can find a short in a PC trace down to 1/4" of the short). That's a lot easier than tearing the coils apart, until you find the fault

yes but that doesn't show me specifically which one it is. I would have to disassemble the coil and band switch assembly to trace which one it is, which is what I suppose I will have to do.

If you download the manual, it shows you which coils are for band 4. In fact , in the schematic it specifically shows the switch in band 4 position.

Problem I am having is the lower three bands work fine but fourth band is dead. That"s why I need coil designation. Thanks John

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Biggest problem is silver mica disease in the IF cans.
 I had 11 Hallicrafters and all had that problem, besides filters and re-cap.

I am needing a coil description and placement to identify which coils are for which band. Also looking for a source of parts for it?