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.
73,
dave
wa3gin
Jim Brown wrote:
On Fri, 4 Feb 2005 18:19:19 -0500, Tom Rauch wrote:
Inside the radio, the negative leads of any HF radio and
almost all VHF/UHF amateur radios are virtually always
connected together via the chassis or PC board grounds.
You're thinking resistance, not inductance or loop area. When you
get the power via the closely paired cable (even better if it's
twisted), you minimize the loop area of any issues with RF on that
power connection. If you use only the body of the car for the
return, you get a low resistance (and low inductance) for that half
of the dc path, but there's a big loop area between the positive
lead and the car body, and any trash on the power will then radiate.
AND that big loop will act as a receiving antenna, coupling RF onto
the power line. That could be a problem if the microprocessors are
using the power system to communicate, which I am told some do.
Jim Brown K9YC
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