From Newsgroup: alt.ham-radio.packet
On Sun, 12 Jun 2005 14:25:31 -0400, mike <
ki4fyy@yahoo.com> wrote:
I have a problem with one of my vehicles supplied with an APRS system.
It is a 10-year old minivan. The APRS radio system is a small 2meter
(~4W) Johnson data radio driving a linear amp to about 25-30W, fed to a >through-the-glass-mounted antenna on the rear side window. The APRS is
done via a TinyTrak module and an OEM GPS board / magnetic mount
antenna. The APRS system works fine, but it affects the car radio in an >annoying way -- every time the APRS radio transmits, the car radio
starts 'scanning' and jumps to a random station. This happens on both AM
and FM. If I remove the linear amp from the system, the problem changes
from 'all the time' to 'most of the time'.
The system is powered by the car's cigar lighter, and all the APRS stuff
has a common ground. Can anyone help me to figure out what is causing
this and then how to eliminate it?
Mike,
Consider the source and ignore the ignorance. Your question isn't
stupid as someone might imply....
Several things might be causing the problem. One is the receiver in
the car is just too susceptible to rfi. The only solution there is a
new radio.
The first thing I would do is to find an HT radio and/or another ham
with a mobile that can park near your car and transmit. If the
problem still occurs, you may need to replace your car radio.
If you don't bother it with radios that aren't integrated into the
car, then try either running a separate set of power wires from the
battery to the APRS radio/amp.
If that doesn't work, get some toroids and wrap them with each of the
wires from the rig including the power cord and antenna leads.
If that doesn't work, then you may need to do so to the car stereo,
not nearly as simple a task.
You may consider getting a filter from an automotive store or Radio
shack to connect to your power cord. That may also be a viable
alternative.
Don't forget to check where the antennas are as you would not want the
two meter antenna next to the car-radio antenna. I suspect it is safe
to assume you didn't buy a splitter to tie the car radio antenna to
the ham rig so that should not be a problem.
If the car radio is a cheap knock-off of an expensive, colorful, bells
and whistles radio, it is quite possible that the radio didn't take
into consideration that a transmitter might be installed in the same
car and cannot handle the RF.
Good luck, keep us posted.
Buck
N4PGW
Buck
--
For what it's worth.
--- Synchronet 3.21b-Linux NewsLink 1.2