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Model 90 1st Detector Coil
#2

Hi Alan,
Well your lucky it isn't secondary it's fairly critical in terms of # of turns. The primary does two things it provides a path for the dc hv to get to the plate of the rf amp tube and it inductively couples the rf signal to the input of the mixer (some called it the 1st det).
The # of turns isn't particularly critical as it isn't part of the tuned circuit. What I've done is just measure the width of the winding and rewind the new winding to the old width. As long as your wire ga is within a few # the width is going to close enough.
Some bake the coil at low temperature after the rewind to dissipate moisture from the form. I've been lucky and haven't had to to make a rewound coil operate properly. The osc coil are more sensitive to the moisture issue, it lowers the Q (efficiency) of the coil.
Sound like you have a good plan dive it and do her!

GL

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry


Messages In This Thread
Model 90 1st Detector Coil - by lasurveyor - 11-18-2017, 07:44 PM
RE: Model 90 1st Detector Coil - by Radioroslyn - 11-18-2017, 09:02 PM
RE: Model 90 1st Detector Coil - by morzh - 11-18-2017, 09:05 PM
RE: Model 90 1st Detector Coil - by lasurveyor - 11-19-2017, 01:11 PM
RE: Model 90 1st Detector Coil - by morzh - 11-19-2017, 01:25 PM



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