[RFI] HF Mobile Installation in 2001 Mazda

[Tom Rauch]

> I agree with Jim...and in Fords that have a variable high
voltage
> ignition system that radiates and couples to existing
factory installed
> loops of single threaded 12+vdc lines, you got one massive
RFI problem
> running another single 12vdc line from the ham radio to
the battery.

Hi Dave,

Why don't you connect a signal generator in differential
mode to the battery leads and measure the RF ingress into
the radio, and compare that ingress to levels from the
antenna.

Or if you want to do it crude and simple, pull the antenna
and slap a dummy load on the rig.

I did this all *extensively* when trying to debug a 95 Ford.

All the racket you hear will be picked up by the antenna.
NONE will come in via the power cord, and if it does I
guarantee you moving the ground lead won't make any
difference you would ever be able to measure.

Any issues you have in vehicle wiring are almost 100% common
mode, which nothing to do with "loops" or push-pull
(transmission line mode) excitation of ground and hot wires.
If that was a problem, you'd be much better off to fix the
radio than the car. That "ground to the battery" thing is
the silliest installation myth I have ever heard. All it can
do is make problems worse.

73 Tom