[RFI] HF Mobile Installation in 2001 Mazda

[Jim Brown]

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