Have you ever needed to replace an audio transformer in an early Atwater Kent radio? Were you frustrated when you could not find a replacement that would fit in the original can? Don't give up, there is a solution to your problem! A fellow radio restorer came up with a brilliant idea to solve this dilemma. I have reprinted the letter as I received it (with permission of course!)
What do you replace AK audio transformers with when they go? No parts catalogs I'm familiar with have anything close in values to the originals. I have found a solution and it is not resistance or impedance coupling and it fits directly in the original can and can be picked up at almost any junk store on every visit or you may even have a couple of them just lying around the house and don't even know it. Stumbled onto it quite by accident and have never seen anyone write up about it before.
First you need a Werstern Electric telephone ( standard desk model, either dial or touch tone); open it up and locate the bell assembly. Attached to the bell assembly by two screws you will find a coil (which is in fact really a transformer as there are two completely isolated coils which are very close in resistance values for what you need in an AK audio transformer). Remove the entire assembly including the core which ironically looks very close to what is originally in an AK audio transformer! I wrap electric tape around the top and bottom of the core to hold it centered in the coil. I determine which is the primary and which is the secondary and seal it into the original AK can. There is even a place on the new transformer that you can solder the antique wires to if you don't want the newer looking wires of the new transformer to show underneath the chassis
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