RE: 10.7 mHz Discriminator Transformer Repaired!

Posted by strijw426 (A) on September 23, 2011 at 17:12:12

In Reply to: RE: 10.7 mHz Discriminator Transformer Repair posted by strijw426 on September 21, 2011 at 18:15:02:

Today I received a set of various small value capacitors to try on the tuned circuits of the discriminator transformer. I had left the slugs of the discriminator untouched during the repair so that when the correct value of capacitor would be placed in the circuit it would restore near normal operation when the right value was selected. It turned out the correct value was 27 pfd for both the coupling capacitor and the capacitor across the primary winding.

The original mica wafer capacitor that was built into the base incorporated dual capacitors, one for the primary winding and the other for the coupling capacitor.

I believe these values would be typical for 10.7 mHz IF and Discriminator transformers in other brands of tube type FM tuners.

Valuable assistance was provided by Edward J. Engelken who has been active in antique radio repair for quite some time.

I used ceramic capacitors of 5% NPO type for the replacement parts.

Joe

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Follow Ups Full Thread

Topic - 10.7 mHz Discriminator Transformer Repair/Replacement - strijw426 13:13:05 09/18/11 (13)

RE: 10.7 mHz Discriminator Transformer Repair/Replacement - strijw426 17:20:47 05/15/13 (0)

RE: 10.7 mHz Discriminator Transformer Repair/Replacement - R. Mercure 14:41:42 09/18/11 (11)

RE: 10.7 mHz Discriminator Transformer Repair/Replacement - strijw426 15:48:57 09/18/11 (10)

RE: 10.7 mHz Discriminator Transformer Repair/Replacement - strijw426 04:01:06 09/19/11 (9)

RE: 10.7 mHz Discriminator Transformer Repair/Replacement - R. Mercure 09:30:51 09/19/11 (8)

RE: 10.7 mHz Discriminator Transformer Repair/Replacement - strijw426 11:08:35 09/19/11 (7)

RE: 10.7 mHz Discriminator Transformer Repair - strijw426 09:36:46 09/21/11 (6)

RE: 10.7 mHz Discriminator Transformer Repair - BFitz 12:02:54 09/21/11 (5)

RE: 10.7 mHz Discriminator Transformer Repair - strijw426 18:15:02 09/21/11 (4)

RE: 10.7 mHz Discriminator Transformer Repaired! - strijw426 17:12:12 09/23/11 (3)

RE: 10.7 mHz Discriminator Transformer Repaired! - BFitz 09:49:36 09/24/11 (2)

RE: 10.7 mHz Discriminator Transformer Repaired! - strijw426 14:54:07 09/24/11 (1)

RE: 10.7 mHz Discriminator Transformer Repaired! - strijw426 07:02:24 12/16/12 (0)

Follow Ups

RE: 10.7 mHz Discriminator Transformer Repaired! - strijw426 17:12:12 09/23/11 (3)

RE: 10.7 mHz Discriminator Transformer Repaired! - BFitz 09:49:36 09/24/11 (2)

RE: 10.7 mHz Discriminator Transformer Repaired! - strijw426 14:54:07 09/24/11 (1)

RE: 10.7 mHz Discriminator Transformer Repaired! - strijw426 07:02:24 12/16/12 (0)

RE: 10.7 mHz Discriminator Transformer Repaired!

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