[R-390] Re: Line filter issues?

[AdamAnt316@aol.com]

Here's more on the issue. A couple of weeks ago, when testing a small 
homebrew amplifier/speaker combination to use with the diode load input, I noticed 
some buzzing coming from the speaker. At this point, the hum was not audible 
from the set's audio on any band, with much of it unnoticable if there was a good 
signal from the receiver, or if the speaker was moved away from the set; it 
would go away completely when unplugging the variac setup I always use to power 
up my radio, and was still present when using no variac whatsoever. However, 
during a recording session of a local BC oldies station, the hum began coming 
through over the BC station with force. At first, I attributed it to the fact 
that I had taken off the Utah plate for display purposes, but putting it back 
on made no difference whatsoever. Earlier today, I decided to see if the noise 
was still coming through, and it was still present, so I began turning off 
various appliances in the house (none of the other line-powered BC sets I've 
tried have exhibited this interference), but this had no effect on the buzzing. I 
then tried using a small transistor radio tuned to the same station to trace 
the source of the buzzing. I got clear reception until I got within a few feet 
of the receiver. I thought that it was perhaps the homebrew variac setup 
which was causing the interference, but trying a commercial variac instead had no 
effect, and unplugging the R-390A from either variac got rid of the buzzing 
altogether. I can live with the problem for now, since it doesn't appear to be 
affecting most of the SW bands, but I would like to find a solution which 
wouldn't affect the look of the set too much (i.e. I'd rather not have a IEC 
connector present in the back of the set, but if there's no way around it, so be it; 
I'll just have to replace the molded plug on the new IEC cord with the 
military-style three-prong plug from the old one!). How hard is it to access the old 
line filter without displacing the rest of the radio? TIA.
-Adam
(BTW: I tried sending this twice from AOL Web Mail, as suggested in the 
NoMIME FAQ, and it was rejected as spam by qth.net's filters both times. 
Strange...)

Adam Vaughn 
Collector of old computers, video game systems, radios and other electronic 
equipment... 
Visit my page at
http://www.angelfire.com/ma2/AdamVon/index.html


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