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RF Coil Question 91 type 126
#1

The Antennae coil on this 91 (part #2 - Philco part = 32-1069), appears to have a magnetic wire wound around the outside of the form and a little small coil that the antennae connects to (25 ohm) that appears to be wound inside a small disk at the top of the coil assembly. This 25 ohm coil appears to be wound with a cloth covered wire with three tiny strands inside.

Am I right that the 25 ohm coil is just sitting at the top of this assembly? Or is the magentic wire wound over the cloth covered wire, with the wire terminating in that disk at the top?

Anyway, I found that one of the very fine cloth covered wires had been clipped by a mouse inside the coil, where it ran down the inside of the coil down to the lug. I was able to tin the three ends of the cloth covered wiring and solder on a fine piece of enamel coated magnetic wire and reconnect it to the lug again. After this "fix" the coil measures spot on 25 ohms just like it should.

The coil looks brand new with no green discoloration at all, so for now I am going to try this out and see how it goes. Unless you guys tell me I am crazy to be doing this. I can pull and rewind the coil if necessary.

I have an open winding in my Detector Transformer (part #12) on the 4.5 ohm side of the transformer that I still need to address. Starting to work that.
#2

Update: Just to help others out here with a similar issue or part.

Part number 12 on my diagram was Phico part number 32-1070. It has two coils a small secondary coil wound around a large primary coil.

My primary was fine so I did not rewind it, instead I just rewound the secondary. I merely followed the directions from here:

http://www.philcorepairbench.com/tips/svctip36.htm

I counted my coils with a magnifying glass and dragging a pin across it to not lose my place. One thing, on this coil the "finish" is before the "start". The diagram on Philco repair bench shows the finish tab located after the start mine was NOT that way. No biggie! I counted my windings just before the finish and found 25 wires. What this actually means is you start a the start and wind 24 full trips around the coil and the last trip is only a partial because you stop at the finish tab, which is before the start tab. The coil is wound the same direction as the original which is clockwise if you are looking from the bottom of the coil.

I used AWG 32 magnetic wire which was just right and my finished coil wound up nearly identical to the original in every respect.

I put this out here because when I went to do this work I couldn't find a count of the coils, or any information on my part number (listed above), so I figured I could save someone else the trouble if they search on part number.

I also followed all the directions in the link above. Once I had the secondary coil counted (did this four times to be sure), I carefully removed it and then carefully removed the nitrocellulose seperating it from the primary. I then wiped off and cleaned the primary, which had no green or any other discoloration on it. I swabbed it off with a weak ammonia solution to neutralize any remaining acid and then rinsed with water and let dry thoroughly.

Then rewound over a strip of plastic from a blister package (see link above).

The one thing I did a little different, was I kept a hot glue gun (warm melted plastic glue) on hand and when I had the coil wound nicely the way I liked it, I put tiny (very tiny) dabs of hot glue on the coil and smeared it flat with my fingers to lock the coil in place. This was almost a direct replacement for the waxy substance they had in place on the original coil and it worked great!

I put this back in the radio and together with the repair above to the mouse nibbled wire going to the antenna coil, the radio now works AWESOME! The antenna now works the radio plays much louder and clearer and picks up many more stations correctly.

I checked all my other coils and they are fine, but I might rewind the oscillator coil(05985) anyway while I am under the hood, just because these things go bad over time.

Anyway, now the only problem is a slight howl when tuned to the strongest of local stations. Does anyone know what might be causing this?

Far away stations are fine and do not have this issue.

Oh....and the 60 Hertz AC buzz is gone now too.....so if you are having that problem....it might be a bad coil.

Thanks again to everyone that helped this newbie (me) out on this repair. Especially, Tom Forbes and Ron Ramirez for all their patience and pointing me in the right direction multiple times.

I might still have a few issues to fix but it sure sounds like it is playing right now. And removing the antenna wire now makes a BIG difference in receiption.




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