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box style shadow meter and magnetism woes
#9

>I didn’t do the ones in the tone control…

Your output transformer and the 80 tube is going to hate you when any of them short.

306v seems reasonable.

The meter movement is dependent on the plate current level on the mixer and two IF amps. The more current the wider the shadow. This is because the plate current is controlled by the AVC voltage. It's the dc voltage found on the left side of #26. If you follow it you find it goes to the control grid of the the previously mention tubes. The more negative voltage on the grid is less current/the more positive the more plate current. Also the level of signal at the ant determines it. It takes a strong enough signal to make the meter get a narrow line at it's center.

Something else that determines AVC voltage is the diode section of the 75 tube.

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


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RE: box style shadow meter and magnetism woes - by Radioroslyn - 04-28-2023, 03:44 PM



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