[TowerTalk] Station Ground

[Jim Brown]

On Sun, 16 Jan 2005 09:39:23 -0800, Michael Tope wrote:

>
>I just remembered that there are these excerpts from 
>factory 2-way radio installations guidlines for Ford, GM, 
>and Crysler in the ARRL RFI Handbook. Here is a 
>summary of what they recommend:

When you're considering the validity of recommendatilons from auto 
mfrs, consider that some of them are notorious noise generators. 
Fords, for example, are JUST AWFUL!  By contrast, my Volvo S80 is 
pretty good. 


>Chrysler makes a good point here about fusing the 
>negative lead which hadn't occured to me. If that negative 
>lead fuse opens you could end up forcing all of your 
>supply return through the coax shield feeding the antenna, 
>and you wouldn't know it until the coax melted. Seems like 
>the best method would be to run the radio's power return 
>wire to the chassis metal right next to the battery or to the 
>negative battery terminal to chassis connection point 
>(same general area) and connect the radio's power
>return wire to that point without a fuse. 

I strongly concur that fusing the negative lead in a negative 
ground system is a very bad idea. Remember that the major function 
of a fuse (or breaker) is to blow if something goes wrong that 
could be destructive or unsafe. If the negative fuse blows in a 
system that is not properly grounded, the positive lead fuse that 
most needs to blow probably won't.

Jim Brown  K9YC