[RFI] RFI in a car

Jim Brown jim at audiosystemsgroup.com
Sat Jul 23 11:23:02 PDT 2011

On 7/23/2011 5:42 AM, J.Gordon Beattie, Jr., W2TTT wrote:
> Have you bonded EVERY piece of metal to each other with flexible strapping?

Yes, except that exposed braid will quickly oxidize.

> This needs to include body panels, frame sections, exhaust sections, etc.
> Doing this should help knock down the 20 RFI to your radio,

Yes. I bought my Toyota Sequoia about five years ago and took it into 
K9IKZ's heated garage (it was winter in Chicago) to figure out antenna 
mounting.  First we poked around with a DC meter looking for anything 
that was bonded to the chassis.  The short answer is that NOTHING was -- 
too much paint in the way.  We finally found one of the bolts holding 
the roof rack had continuity to at least something (but not to a bolt 
four inches away), so I used that as a return for the antenna, which I 
mounted to the roof rack.

The antenna worked fine, but because there was virtually NO chassis 
bonding, as little as 50W on 20M caused the car's main computer to lock 
up and put the car into limp home mode.  By the time Ifigured that out, 
I was in the process of moving cross country, which is when I wanted to 
work HF mobile. Since I've moved, all of my energy has gone into my home 
station, so I've not taken the time to fix the Sequoia, which would 
likely be a MAJOR effort.

73, Jim Brown K9YC

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