The AM Forum

I have an SX117 in reasonably good shape that has been on a shelf waiting for repair for years - like 20 years! The problem is that at least one of the 50khz IF transformers is open. I have taken it apart and it is not open anywhere that can be seen. The coil looks like it is scramble wound but it has a tap or actually two coils. On a good one, one side measures about 20 ohms and the other about 30 ohms. The wire size as near as I can determine is #36 enameled. The windings are encased in gook and the form is broken.

I have a (borrowed) coil winder and I have new a new form but it will be a guess as to the exact number of windings and also how to wind with the two coils (tap).

Knowing the wire size and resistance and form diameter I can get a rough idea as to number of turns.

I only found one reference to anyone else with this problem although it has to be more common than that. It was mentioned that the SX-96, the SX-100, and the SX-101 might have the same transformer. If so maybe I could find a junk unit to steal one from.

Has anyone wound one of these before or have any ideas on a replacement?

I expect the transformer from any of the 50 Khz. IF Hallicrafters receivers from the SX-96 on should work.  This would include the SX-96, 100, 101, 111, 115, 117, and 122.  The SX-88 transformers are different and I wouldn't bet on the S-76 (the first of the 50 Khz. receivers) working either.  You MAY have to transplant the guts to your housing since those might have varied over the years but the tapped coil setup has always been used from the 96 on.

I don't think failure of these is common.  I have at least one of each of the 50 Khz. IF models including the HT-30 transmitter that uses a 50 Khz. L/C sideband filter and the only 50 Khz. IF transformer I have replaced was in a friend's SX-117 and that IF transformer was destroyed by a loose power transformer during shipping, it also took out most of the tubes.

Doug,

I "may" have an SX-100 parts receiver.  I know its not downstairs since I have look extensively for it in the storage area.  Saying that, it may be in my outside parts building.  When thinks warm up just a bit, I will look for it.  If its not there, I gave it away when I had the GMS giveaway fester.  So if you can wait a bit, I may be able to help.

Joe, GMS

Joe,

  Thanks, that would be great if you could find one or maybe two. I have to check but I thought there might be another one that is bad. Attached are photos of what they look like. The part number is 050-200735.

And if anyone else has any ideas or possible parts units where I can get one that would be great.