Motorola 7 inch tabletop

[dieseljeep]

Originally Posted by timmy

Ok well I cannot find a reason for the hum in the audio so I'm wondering if it's at all possible that the noise I call a hum Could be a buzz , could this maybe coming from the IF and sounding like an ac hum. I had placed an electrolytic cap between the audio amp and output and was able to filter Alittle bit but no matter where a cap is put, audio or power supply the hum or buzz is still there. The ground on the tube sockets are all soldered. Swapping tubes make no difference. All that seems left is the IF or the verticle but I went over the verticle and found nothing.

A hum at minimum volume usually indicates power supply hum or AC ripple getting into the B+. Disconnect the speaker and with an 8 ohm or so dummy load, signal trace the audio circuit to see where the hum originates.