It IS critical that all conductive parts of the vehicle be bonded
together. It is critical for two reasons. First, because those parts
carry antenna current on both TX and RX, and to be effective as a
counterpoise, they must have good electrical contact. You're absolutely
right about paint. It's a HUGE issue.
Second, good EMC design calls for cables supporting signals for
sensitive circuits to be run in close proximity to a "ground" plane.
Noise current is coupled far better to the much larger ground plane than
to the cables. But this falls apart if there is a break in the "ground"
plane, greatly increasing coupling to/from those cables. This mechanism
is a likely cause (or contributing cause) to my 20M RF locking up the
computer in my Toyota.
And, of course, it has long been good practice to bond the tail pipe to
minimize old fashioned automotive noise. :)
73, Jim K9YC
On 10/9/2017 10:33 AM, Rick WA6NHC wrote:
My rule: Bond EVERYTHING to the chassis, including chassis elements
to each other (paint is a pretty good insulator). While that does
have a *small* effect on noise (the every wire IS an antenna
consideration); mostly bonding is to keep the RF (more correctly RFI)
out of systems where it doesn't belong , including induction and
radiation along the power cabling; to radiate from the antenna (while
power sources are also another good place to provide some twist in the
cable). More bonding means more energy to the (intended) antenna and
higher efficiencies.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
