I received a direct email from a member of this reflector asking what my comments about ground loops in an amplifier chassis had to do with the SX-28 hum discussion.

Sorry, I wasn’t specific enough.

If along the way someone has moved a ground from some source of hum to a more convenient location during a repair, requiring the AC to return through a path via the chassis that also carries an audio signal return can and will (to a greater or lesser degree) impress hum into the audio. If 60 Hz, it can be a filament connection.? If 120 Hz it can be a B+ filter return.

That’s all !

Mike/
K5MGR
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