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Model 51 IF transformer - Printable Version

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Model 51 IF transformer - tpcaz - 02-26-2011

I've been working on a Model 51 chassis in an attempt to bring it back to the glory it once knew. My latest stumbling block was finding the 1st IF transformer (#12 on the schematic) had a fried primary winding. I inadvertantly miswired it after removing the transformer to replace some bad wiring in the chasis.

I took the assembly apart in an attempt to locate where it had opened up. It was not at the begining as I had hoped. As I carefully pulled off the wire on the winding, I kept finding sections broken. I would ohm out the wiring after each section thinking I would finally find the last break and have continuity. No luck.

So here I am after investing many hours on this set to only to hit a dead end.

What could I use as a suitable replacement for the 1st IF transformer?
Something from another model radio or are there aftermarket replacements that would work?

The good secondary winding, and both windings of the 2nd IF transformer measure out around 156 ohms

Any help would be greatly appreciated.

Re: Model 51 IF transformer - exray - 02-27-2011

It doesn't appear from the schematic that the primary is tuned to resonance. If you can find some wire of the same gauge I'd bet that you could rewind the winding with success as it wouldn't be terribly critical.

Worth a try if you cannot locate an original.

GL,
Bill

Re: Model 51 IF transformer - Radioroslyn - 02-27-2011

Pssst. That coil is the first rf transformer. It's a Tuned Radio Frequency set (trf) Not a superhetrodyne which would have IF transformers. As Bill said winding isn't very critical . You could wind 20 or 30 turns of 30-38g magnet wire near the bottom of coil wire it to the pins and you should be go to go.
Terry

Re: Model 51 IF transformer - tpcaz - 02-27-2011

Thanks for the responses. I do appreciate the inputs.

I don't think doing my own winding is in the cards. Though I was able to locate some info on bypassing defective IF transformers by using a coupling capacitor and a resistor. I might give that a try and hope for the best until something comes up. Still other issues to deal with in this set. One step at a time.

The Model 51, Baby Grand, was the successor to the Model 50 and used a superheterodyne circuit and five tubes. The radio is a superhet and not a TRF. The tubes are 24, 35, 24, 47 & 80. Even on the dial escutcheon it says Superhet 5 tube. The illustrated parts listing and the chassis component view, as found in Riders Volume 2, shows items # 12 and #16 as the 1st IF and 2nd IF respectively. They are identical components, both have two windings placed on a wooden spool and housed in a small round can. Since both are not adjustable, they have compensating capacititors attached, which I asume are for tuning the circuit for 175kc. This is what makes it difficult to find a replacement.

Re: Model 51 IF transformer - Radioroslyn - 02-28-2011

Sorry I had the model 50 on the brain. If the IF is 175kc That was a standard IF frequency back in the '30's. If you like I can take a look and see if I have something that will work. Don't think I have a Philco can but maybe a replacement. Winding an IF coil would be no fun particularly at 175kc.
Terry