RFI
[Top] [All Lists]

Re: [RFI] HF Mobile Installation in 2001 Mazda

To: "David Jordan" <wa3gin@erols.com>
Subject: Re: [RFI] HF Mobile Installation in 2001 Mazda
From: "Tom Rauch" <w8ji@contesting.com>
Reply-to: Tom Rauch <w8ji@contesting.com>
Date: Sat, 5 Feb 2005 00:32:55 -0500
List-post: <mailto:rfi@contesting.com>
> SO, there are things that can be done to remove the RFI.

Absolutely.

I agree fully with that.....but running the radio negative
lead  to the battery negative post is NOT one of them.

> Just running ground strap from the alternator to that
awful negative
> battery lead removed all the whine (what there was of it)
from the 2m
> radio.

The phrase is "ground loop". If you ground to the battery
post the negative lead entering the radio is or can easily
be at a *different* potential than the point where the coax
leaves the radio (unless you also ground the ANTENNA only to
the battery post).

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.

I do the same thing. I just don't ground the rig's negative
lead to the battery. I want it to always be at exactly the
same potential as the antenna ground. I guess if you strap
the battery to the chassis in enough places it is OK to
ground to where the straps connect to the battery, assuming
you can keep the acidic junk off the connections. I
generally add a good ground point for radios and internal
gear to the firewall or something that is an integral part
of the firewall. I figure it makes no sense to bring the
negative leads up through higher resistance connections to
the engine compartment.

My only vehicle with a frame rail that is not integrated
into the chassis is my full size pick-up truck. It floats
the fenders and passenger compartment from the frame rails
in an effort to reduce NVH in the passenger compartment.
Only the bed bolts solidly to the frame rails. The cab and
front end sits on multiple rubber mounts. I've never seen a
car manufactured after the 60's that is built like a heavy
duty truck with floating frame rails.

In my truck, I bond the cab to the frame rails at points
removed from normal factory grounds. This greatly reduces
RFI.

73 Tom

_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi

<Prev in Thread] Current Thread [Next in Thread>