04-03-2025, 08:12 PM
> The cathode as noted is wired directly to the ground side of the heater filament for that tube, not to the #17 and 18 grid leak resistors.
I think what you are seeing are #'s 38 and 40. #17 and 18 may or may not be soldered at the ground side of the cathode-heater connection but do have to be connected to the SW osc coil and chassis ground at some point.
I would go ahead a align the IF transformers by applying a low level 460kc 400cy to the grid cap of the 6A7. Two of the adjustment are going to have HV on them as they are in the plate circuit of the 6A7 and 78 tubes. #20, 22, 26, and 28 are the trimmers for the IF .
After that check the SW band and see what frequency coverage is and that will tell us about the 2250 mmfd cap.
The G2 has + voltage on it all the time as it's acting as a triode plate. The rf output is coupled off by using #7 250mmfd cap at the bs. That in turn sends the signal to the primary of #8. Top coil is the BC band bottom is SW. 2ndy of the coil is the grid winding which determines the frequency and the primary provides the feedback for oscillation.
A .66 mfd vs a 2250 mmfd is a BIG DIFFERENCE. Don't think that is the right cap for the job or maybe the colors have discolored making it hard to determine.
I think what you are seeing are #'s 38 and 40. #17 and 18 may or may not be soldered at the ground side of the cathode-heater connection but do have to be connected to the SW osc coil and chassis ground at some point.
I would go ahead a align the IF transformers by applying a low level 460kc 400cy to the grid cap of the 6A7. Two of the adjustment are going to have HV on them as they are in the plate circuit of the 6A7 and 78 tubes. #20, 22, 26, and 28 are the trimmers for the IF .
After that check the SW band and see what frequency coverage is and that will tell us about the 2250 mmfd cap.
The G2 has + voltage on it all the time as it's acting as a triode plate. The rf output is coupled off by using #7 250mmfd cap at the bs. That in turn sends the signal to the primary of #8. Top coil is the BC band bottom is SW. 2ndy of the coil is the grid winding which determines the frequency and the primary provides the feedback for oscillation.
A .66 mfd vs a 2250 mmfd is a BIG DIFFERENCE. Don't think that is the right cap for the job or maybe the colors have discolored making it hard to determine.
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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