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Model 89 code 123 #36 tube - Printable Version

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Model 89 code 123 #36 tube - tmr63 - 05-30-2019

I am Restoring a model 89 with the usual coil problems.  I found good information on rewinding the # 14 oscillator coil.

I also have a bad secondary winding in the 1st if coil #18.  Did anyone save their notes on this coil?

I assume the wind is clockwise however does anyone have the number of turns and the wire size.
Is the wire size critical or is close enough ok?

Thanks for any help you can give me>

Tom

RE: Model 89 code 123 #36 tube - Jake Blake - 05-30-2019

I would like to hear some more discourse on this from more-knowledgable minds on this subject, ( than mine), as I have heard snippets of it in the past. The bad rap has me hesitating diving into my own 89, but I'm scratching my head at it because if there's any truth to it, why is my 89 still playing a little without a restore?

RE: Model 89 code 123 #36 tube - Ron Ramirez - 05-30-2019

The necessity of rewinding an IF transformer does not come up very often. I've never attempted it. Obviously it can be done, though. You would need to unwind the original winding, observing the direction of the winding. It would also be necessary to measure the diameter of the old wire with a micrometer to be sure you get the proper size wire for rewinding. Finally, you would have to come up with a way to wind a new winding on the old form of the same shape, width and spacing as the original winding. Getting a new winding too close or too far away from the secondary will cause issues.

It's much easier to find a junk set and pull the needed IF transformer from it. Lots of model 89 and 19 sets were made, so it isn't too difficult to find a parts chassis.

RE: Model 89 code 123 #36 tube - tmr63 - 05-31-2019

Thanks for the advice Ron

I tried to unwind the original wire, splice it and rewind it back on in the same place.

It appears to work if I put the IF frequency into the primary and look at it on the secondary.

However it's 180 degrees out.  I was careful to rewind it in the same direction however it appears that I got it wrong.
The schematic shows the dots on the core which would assume  means that the output should be in phase.

will try to rewind it in the opposite direction.

I will start looking for a parts chassis in the meantime.

Thanks

Tom

RE: Model 89 code 123 #36 tube - Steve Davis - 05-31-2019

Tom, phase won’t matter on the IF transformers. The secondary is driving the grid of the next tube. It couldn’t care less.

Steve