[Milsurplus] Radio interference

[Neil Barnett]

> I assume
> you are using both a positive and negative lead (both fused)  all the way 
> from the battery (the negative fuse protects the radio from the starter 
> cranking current
> should the negative to the engine block open).  Using the vehicle frame 
> only, for the negative lead, introduces noise to the radio because the 
> negative lead (the
> frame) has engine, generator,etc. noise on it.  Running a negative lead 
> (even in addition, where the radio negative appears on its case/chasis) 
> shorts out most of
> this noise.

Nicely stated.  But what happens if the negative lead fuse
does happen to open?  The radio's DC return path is now
via the coax cable and its connection to the vehicle chassis
at the antenna feed point.

Noisy reception?  Yes, but even worse is that high current
draw (20 Amp) while transmitting now utilizes this coax
cable route, with possible PC track and/or cable damage.

Check that negative lead fuse regularly!  Especially if you
notice a sudden increase in hash level on receive, or the
radio appears RF hot while transmitting.

73 de Neil ZL1ANM