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On a positive note, I replaced the AF amps in my Drake R-4B and R-4C receivers.? The goal was to get hum/buzz down to zero with the AF control wide open.? With a screwdriver connected to the AF amp’s ground lead, I wiped across the chassis in search of the lowest hum/buzz level.? I found several points that met this criteria.? Once found, a hole was drilled in the chassis and a solder lug added for the ground connection. ?At these points, AC heater ground current is minimal, sometimes cancelling altogether.?

Thanks Paul.? That screw driver wipe technique is something I will need to remember.? I also do a fair amount of old stereo restoration and your technique will sure come in useful.

73
Don N9OO