03-11-2006, 05:16 PM
With little doubt you have an open grid resistor in the triode section of the AM detector tube (75) or possibly the audio output tube (42).
With the power off, check the resistance of the 1 meg resistor #35.
If that is OK check the 500K (0.5Meg) that connects to the grid of the audio output tube (42); or, measure the grid voltage- usually -20-25VDC.
The higher the value of resistor means the higher chance of increased resistor value. 20% error fine; above that means change it.
Let me know what you find.
With the power off, check the resistance of the 1 meg resistor #35.
If that is OK check the 500K (0.5Meg) that connects to the grid of the audio output tube (42); or, measure the grid voltage- usually -20-25VDC.
The higher the value of resistor means the higher chance of increased resistor value. 20% error fine; above that means change it.
Let me know what you find.
Pete AI2V
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