Advice on replacing IF transformer
 

Hi, I am new to radios and am trying to restart a Stewart Warner 62T36. The first IF transformer is bad (455kHz, part number 502102 or 16-6658). Does anyone know if these can be replaced? Where would I buy one? Thanks!! Henry

Re: Advice on replacing IF transformer
 

What is the fault with the transformer? Unlike European sets, American radios of this era are notorious for faults in the padding capacitors inside the transformers.

Re: Advice on replacing IF transformer
 

According to the schematic the IF transformer's tuning capacitors are of the variable type, need more info regarding the defect:

http://www.nostalgiaair.org/pagesbym...7/M0020757.pdf

Lawrence.

Re: Advice on replacing IF transformer
 

Hi, from what I can gather on this item the primary and secondary should read 20R. The primary is 20R but the secondary is infinity. There must be a break.

Re: Advice on replacing IF transformer
 

Actually the primary is 22.9R and secondary is broke. Here is a picture of the little beast.

Re: Advice on replacing IF transformer
 

I found this:-

http://www.antiqueradios.com/forums/...c.php?t=165802

I'll give it a try, I just need to pick-up a 100K resistor.

Re: Advice on replacing IF transformer
 

That type of IF transformer seldom gave any problem, unless the fine wire going to the coils has been disturbed or it was damaged by someone or an insect getting inside. The transformers come apart rather easily for inspection. As stated before, more information is needed.

Re: Advice on replacing IF transformer
 

It is strange that it is broken. As far as I can tell the two fine wires entering the coil are fine, and the coil is encased in wax. :shrug:

Re: Advice on replacing IF transformer
 

I thought I had replied but it seems to have gone. Here I go again.

I have used a mini single tuned transformer from a transistor set, connected directly on the valve base. Top coupling to the primary was by a home made capacitor of about 5pF.

Rewinding of the faulty coil should be possible, I do not know what the effect would be of replacing the wave wound coil with a solenoid winding which would be easier to do.

Re: Advice on replacing IF transformer
 

A pile winding with the same footprint as the original wave one would probably be better.


Melt the wax off with carefully directed hot air so you can reuse it to coat the new winding.

Re: Advice on replacing IF transformer
 

Wow, way too complicated for a newbie like me, I'm not sure how to wind the wire - that must take hours?!? I'll try the cap and resistor first, I can tuck it up in the can so as no one knows.

Re: Advice on replacing IF transformer
 

The cap and resistor bodge should work OK but you may lose some selectivity (set not so good at rejecting close in unwanted signals).

Re: Advice on replacing IF transformer
 

That's why I always like to encourage 'newbies' to build a couple of small radios from scratch. Plenty of info on the web for doing this. When most of us started, we wound coils and very often the wire was salvaged from old transformers...as long as it was about the right gauge we just went ahead and did it. All the radio circuits I started with had details on winding the coils....and it doesn't take hours....more likely only a few minutes to wind an aerial coil.

Give it some thought and a try. There is nothing quite like hearing a station from a radio built from scratch....and you'll learn a lot by doing it.

Re: Advice on replacing IF transformer
 

I have not unwound an IF transformer but doubt if there are many more than 100 turns. I have wound a solenoid for a slave clock, using 30,000 turns this did take a while since the wire was very thin and I was worried about breaking it. This was done using an AVO coil winder without the traverse working.

I have thought of a way to make a wave winder attachment but I have other priorities at present and I am not too good at construction but I am quite a good bodger.

Re: Advice on replacing IF transformer
 

I.F. transformers do sometimes appear on EBAY but the only ones at the moment are out of a 19 Set, they would work but if you wait you might get something closer to the original

Re: Advice on replacing IF transformer
 

I have an IF transformer that would be a direct replacement for the one needed, even though it's out of a different make of radio. I'll have to check with the Post Office to see what's all involved in sending it to you.

Re: Advice on replacing IF transformer
 

I've seen the circuit used in the lower priced 5 tube radios in the US, but in the 2nd IF circuit. They really weren't bad in selectivity and sensitivity, but they did lack good AVC/AGC action.

Re: Advice on replacing IF transformer
 

I inquired about the cost of shipping and Customs payment at the Post Office and was quoted around $22 USD. I thought, that was a lot of money to post an item that is in a small package and weighs less than a pound!