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High Plate Voltage on IF tube 39-116
#3

(11-14-2014, 08:49 PM)Ron Ramirez Wrote:  Hi Jeff

A look at the schematic indicates 160 volts is incorrect - it should be 260 volts. Notice on the schematic, the plate of the IF tube connects to the screen grids of the 42 output tubes through the primary of the 2nd IF transformer.

Try injecting a 455 kc signal through the control grid of the IF tube. If you get nothing, then use a 0.1 uF cap in series with your signal generator to block the DC from going into your generator, and inject 455 kc into the plate terminal of the IF tube. If you still have nothing, then there must be a problem with your 2nd IF transformer.

Don't forget to check continuity of the 2nd IF secondary (between the 51K resistor and the green wire).

Yes see it now Ron, the red wire out of the 2nd IF to the 42 tubes. Injected the 455 kc signal in in both methods as you had indicated....very distant faint crackling. I will pull the 2nd IF transformer and see what I have. I did get readings in tolerance (primary and secondary resistance) but something may have shifted in reattaching it.

Thank you Ron.


Jeff


Messages In This Thread
RE: High Plate Voltage on IF tube 39-116 - by jeffgniffke - 11-14-2014, 09:15 PM



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