[RFI] AM radio RFI from 2010 Ford Escape

[Jim Brown]

On 10/28/2010 4:33 PM, John Brosnahan -- W0UN wrote:
>> Between that support and the negative post
>> >of the battery had 2 tenths of an ohm. So I attached a heavy gauge
>> >grounding wire from the frame point, which is above the gas pedal
>> >and already had a nut and washer, to the grounding terminal on the
>> >back of the radio. The static on even distant am stations is 90% reduced.

Chassis bonding in some vehicles is REALLY AWFUL.  I found tens of ohms 
between screws on different pieces of the chassis in my Toyota Sequoia 
(big SUV), and even between screws that were very close to each other 
securing the roof rack to the roof). Paint is the major problem.  It was 
so bad that running only 100 watts on 20M SSB generated enough crosstalk 
into vehicle wiring to put the car's computer into "limp home" mode.

That does NOT mean that you should necessarily bond the radio to the 
chassis.  A better approach is to FLOAT the radio, but bond the coax at 
the antenna, and run a big power pair to the battery.  There is no magic 
in bonding the radio itself, but you do want a very low Z connection to 
the battery, and between the coax shield and the chassis at the antenna.

73, Jim K9YC