[sci.electronics] Amazing radio reception

jbovitz@ub.d.umn.edu (Jeffrey Bovitz) (12/07/90)

No, the Subject line is not an exaggeration.

I have a Sanyo C777 boombox.  The problem I have with it is quite annyoying.
Whenever the power is on, I get reception from a radio station.  The noise
is very small, but when I tune in a real station, and listen to it softly,
the "ghost station" is as loud as the real one.  The same thing happens
with the AUX input and Tape.  My antenna is a simple telescoping rod
antenna.

Has anyone ever heard of this problem before and how to correct it?  I could
take it into a service center, but I don't want to pay $24/hr to have
them look at it and install a little diode or something.  This is getting
quite annoying.  Any help would be great.

Don't send to the address above.  You can Email me at
     moonunit@meteor.wisc.edu, or post it, if you'd like.  Thanx a bunch!

Chris Bovitz

mcovingt@athena.cs.uga.edu ( Michael A. Covington) (12/07/90)

You say your boom box audio contains sound from a nearby radio station
all the time, regardless of whether it's tuned to a station or playing
a tape or whatever?
  
I'll bet it's a very nearby AM station.

First step would be to get some 0.005-uF capacitors (not critical value)
and put one across each speaker and one across the volume control.
I'm thinking that something -- probably the speaker wires -- is acting
as an antenna and the AM radio signal is getting demodulated in the audio
section. ... Put a capacitor across the power supply input, too, if you're
using an external DC power supply.