"Anders" wrote in message
oups.com...
recently my friend and i bought a set of radioshack brand mobile cb's
to mount in our trucks. We went offroading right after we got them and
they worked perfectly. Then the second time we tried to use them we
had a problem with feedback. When i transmitted my friend could hear
me, but i could not hear his transmissions. Instead all i could hear
was a loud beeping tone. we experimented with different things but
were unable to find the source of the problem. Using a third cb we
concluded that it was my friend's cb but still could not find the
source of the problem which is frequent but intermittent. Has anyone
heard of this before???? Any suggestions?

Were the sets new?

Depending upon if the equipment is new and whether it came wired by the
manufacturer (many shop staff are incapable of good wiring practices),
possibilities include:
* Problem with antenna - this can cause RF feedback which, on an AM
CB, will cause squealing noises. If intermittent, check all antenna
connections and the mount.
* Poorly wired microphone - a poorly wired microphone may short out a
couple of pins, which can result in squealing.
* Incorrectly wired microphone - one of the wires in the lead is screened,
and should be used for the mic audio. If one of the other wires is used
for that purpose, RF can get back in the radio and cause a squealing.
* Faulty radio - as intermittent, possibly a poor connection or dry solder
joint. It has also been known for poor design to cause intermittent
problems with feedback.

RF feedback can cause all sorts of problems, but squealing is common
on AM equipment. SSB sets may warble or send a noise on transmit,
FM equipment may transmit a humming or buzzing noise. Cheapo sets have
been known to either send the output into self oscillation or lock themselves
on transmit.


Regards,

Peter
http://www.citizensband.radiouk.com/