-- [ From: Ned Worcester * EMC.Ver #2.5.02 ] --
There are several filters and capacitors that you can find, both to try to
isolate the source, and to reduce it at the radio. The first step to take
is to make sure that everything is well grounded and bonded. You may be
able to isolate whether the noise is coming in through the power or antenna
system. Disconnect coax at antenna, listen for noise level, then disconnect
coax at back of radio and listen. If noise level remains pretty constant
then problem is within power, and that's where you will need to devote most
of your efforts.
You can try to isolate some power noise by disconnecting the radio from the
truck, and running it to another power supply or battery, and turn on the
engine. If you still get significant noise, then most of it is coming
through the antenna or ground. Try running a ground from the temporary
power supply to the truck to see if the noise increases or decreases.
Check the hood grounding strap, try running an additional grounding strap
between the hood and the body. You might also try a shielded power wire.
Get braid at your favorite electronics store and run the positive wire
inside it. Ground the shield at the battery end only. Be sure it won't
touch any hot conductors, else you will have a nice direct short.
There are several good filters available, many of them are sold in the
marine industry for marine or aviation HF use.
Above all, make sure that all of your ignition system is in good shape with
the proper resistor wires and plugs. A new brass cap and rotor might also
help.
Hope some of this helps.
Ned Worcester
'95 SLT CC V8 4x4
-------- REPLY, Original message follows --------
Date: Monday, 13-Oct-97 10:00 PM
From: dritchey@sprintmail.com \ Internet: (dritchey@sprintmail.com)
To: Dakota Mail List \ Internet: (dakota-truck@buffnet.net)
Subject: DML: Radio Interference
Ned Worcester said
>On your post to the DML you noted that you get radio interference. What
types
>of radios and frequency bands? I am assuming that you are talking about
>two way radios rather than am/fm broadcast....
Ned, thanks for the reply. I am getting quite a lot of spark plug hash
directly from the distributor, and I found the source using several loops of
hookup wire as an antenna. It is only within a few inches of the
distributor that the loop picks up the noise. I have two transceivers, one
for UHF and VHF, and there are no problems with this radio at all. The
other is HF, 10 to 160 meter, 100 watt SSB, and this is the radio with the
problem. I run an S-7 noise floor with the engine on.
This truck is my mobile amateur radio station. Thanks Doug N1DR
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