01-26-2022, 05:45 PM
Ok so help me understand what you are saying.
>Since the Radio was converted to a PM and the the mod still has a coil in place for the filter caps vs changing to resistors , I decided to check that "choke?" transformer.
The "coil" you mean the field coil? So you have the back half of the original spkr and the pm spkr together? True be told there is 3 coils on the electrodynamic spkr. Voice, hum bucking, and field.
The transformer doesn't really have much to do with the power supply or filtering. It's there to match the impedance of the plate of the output tube to the voice coil of the spkr. In this case about 2000 ohms to 3 ohms.
If you are measuring the resistance of the field coil and it's 2 ohms that's a problem. It's darn near a dead short. That will make it hum. Replace w/a 500 or so ohm 2 or 3w resistor.
>Since the Radio was converted to a PM and the the mod still has a coil in place for the filter caps vs changing to resistors , I decided to check that "choke?" transformer.
The "coil" you mean the field coil? So you have the back half of the original spkr and the pm spkr together? True be told there is 3 coils on the electrodynamic spkr. Voice, hum bucking, and field.
The transformer doesn't really have much to do with the power supply or filtering. It's there to match the impedance of the plate of the output tube to the voice coil of the spkr. In this case about 2000 ohms to 3 ohms.
If you are measuring the resistance of the field coil and it's 2 ohms that's a problem. It's darn near a dead short. That will make it hum. Replace w/a 500 or so ohm 2 or 3w resistor.
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 it!
Terry
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