When I installed commercial radio equipment in the late 70's early 80's
power leads came with only one fuesed lead - the positive lead. We were
trained to connect it directly to the battery unless there was a
manufacturer installed power tap close by. Most of our radios were the type
that had a main "unit" connected to a control head by way of a thick control
cable. In a car installation "the unit" would be mounted in the trunk. The
ground lead would be connected to a ground stud we supplied by installing a
1/4" bolt thru the vehicle's metal body close by. Most ground leads were
only 3'-4' long because the manufacturers wanted them to be short. If "the
unit" was installed under or behind the seat of a truck we installed the
ground stud thru the floor or thru a piece of double interior wall. If for
some reason we had to run the negative lead into the engine compartment we
never connected it to the battery. We always used a manufacturer installed
ground stud or provided our own if we had to. Industry standards may have
changed since but that's the way GE, Motorola, and RCA had us do it then.
The Motorolas we use at work today have only one fused lead - the positive.
I never saw dual fuses until I bought my first amateur mobile radio, a
TM-241. If you are going to connect the negative lead to the battery by all
means fuse it. But if you connect it to the body there's no reason to
because if the battery's negative lead goes bad there will be no path from
your negative lead to the battery for stray current to follow.
Regarding plastic vehicle bodies, we used a "ground plane kit" which
consisted of a small roll of 4" wide aluminum tape. We would remove the
headliner and install the tape on the inside of the roof in a"H" pattern.
The catch is this only works if you're using body mount antennas. You'd
drill thru the roof and the foil to get a good connection between the foil
and the antenna mount.
Brian KF2HC
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