Posts: 823
Threads: 111
Joined: Aug 2012
City: Lake in the Hills, IL
I've got a strange one. All electrolytic and wax caps replaced. Resistors replaced as necessary. Tubes tested. Set aligned on both AM and FM.
The problem is that I get a hum on AM only and only when on a station. In between stations on AM is silent as well as FM.
Any thoughts?
Thanks,
Eric
Schematic:
http://www.nostalgiaair.org/Resources/251/M0015251.htm
Eric
Lake in the Hills, IL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org
Posts: 1,106
Threads: 88
Joined: Jun 2011
City: Tacoma
State, Province, Country: Washington
Selective hum like this is usually environmental. Try moving the radio to a different area of the house and see if it goes away. My workbench is insane for reception problems. There's some kind of field there that creates a ton of RFI, but if I move the radio under test off of the bench, even just a couple feet, all the noise goes away. Before I discovered this, it nearly drove me mad trying to figure out what was wrong with the radios.
Posts: 2,128
Threads: 18
Joined: Oct 2008
City: Merrick, Long Island, NY
Agree, try moving set around. Most likely a really old dimmer, imported unshielded power supply, shut your bench down completely first.
Posts: 823
Threads: 111
Joined: Aug 2012
City: Lake in the Hills, IL
Thanks BrendaAnnD, out of the basement and away from my bench the hum is minimized. It's just strange that this is the only radio that I've had this issue with.
Eric
Lake in the Hills, IL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org
