26-11-2012, 05:56 PM
Depends what you mean by hum, is it "modulation hum" that kind of hum is usually mains borne and usually shows up on AM broadcast band when tuned into the station, with this type of hum it's volume will increase as you advance the volume control once tuned into the station, it is usually worse on strong local stations, it is normally not present when tuning between stations, the mains filter capacitor can reduce this type of hum but the capacitor should be the X rated type for the job.
The other sources for hum are normally within the receiver, HT hum, wiring pick up hum, heater cathode hum, heater chain wiring radiation etc. When you replace the vol pot/switch pay attention to the routing of the wires as sometimes a high impedance grid circuit (the vol. control) can pick up hum from the mains switch wiring
Lawrence
The other sources for hum are normally within the receiver, HT hum, wiring pick up hum, heater cathode hum, heater chain wiring radiation etc. When you replace the vol pot/switch pay attention to the routing of the wires as sometimes a high impedance grid circuit (the vol. control) can pick up hum from the mains switch wiring
Lawrence
