Quote:
Originally Posted by Terry_VK5TM
I came across an article on winding replacement vintage interstage coupling transformers.
|
That is a helpful article.
There is another way to deal with faulty interstage transformers in vintage radios. Use a part AES supply the PT431:
https://www.tubesandmore.com/product...ssembly-p-t156
So the original lams can often be kept and the faulty winding just replaced by this 1/2 x 1/2 bobbin. For a bigger size the bobbin from their PT124E (3/4 x 3/4) can be used. This avoids the rewind with a lot of fine wire.
One other thing , interesting about interstage audio transformers, the equation that defines their frequency response was practically unobtainium. The response is very dependent on the plate resistance of the driving valve. The equation is in this article on page 15, about my Grebe radio. I derived it from some equations presented by Terman. It does a very good job of predicting the transformer's frequency response shown on pg 16:
http://worldphaco.com/uploads/THE_GREBE_MU-1.pdf