Re: [RFI] HF Mobile Installation in 2001 Mazda

[David Jordan <wa3gin@erols.com>]

Thanks for the fast response Tom.  I always appreciate a thread where
you're engaged in the conversation.  I've spoken to Ford and Chrysler
EMI engineers and they all believe this myth, as you say!

I've done some pretty extensive noise reduction on my Ford. Shielded the 
spark wires, the igniter and re-ran the low voltage fed to the igniter 
controller. The thing is very quiet now.  With a homebrew sniffer it 
really did sound like the low voltage leds to the igniter controller 
were radiating spark pulses. After re-routing the 12vdc I don't hear the 
spark noise but instead the pulses from the three ABS brake sensors 
located on the rear transaxle.

Now, ABS noise aside, the AM radio reception is outstanding where before 
only the strongest stations were good copy.  In fact down at the low end 
of the AM broadcast band I can now monitor the parking lot LP AM station 
at National Airport from almost 10 miles away. I used to have to be 
within one mile to hear it.

SO, there are things that can be done to remove the RFI.

Just running ground strap from the altenator to that awful negative 
battery lead removed all the whine (what there was of it) from the 2m 
radio. I also ran a strap from the battery negative to the frame rail.
Did that because I wanted to run a ground from the fuel pump CROCOM 
brute force filter case to the frame rail. The same frame rail is used 
to connect the ground from the antenna. That frame rail is really the 
vehicle's ground buss, haha.

73,
dave
wa3gin

p.s. When it warms up I'll go after those nasty ABS sensors, haha.

==================

Tom Rauch wrote:

> > 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.
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