[aprssig] Negative Fuses

Robert Bruninga bruninga at usna.edu
Tue Jan 24 21:51:01 EST 2006

>>> rgilson at adelphia.net 01/24/06 7:45 PM >>>
> I can't help but wonder why for many many years 
>Motorola or GE  never put a fuse in the ground of 
>their commercial radios(tubes and transistors).

Because you dont need one if you connect the
negative lead of the radio independently to
FRAME ground near the battery.  A failure of
the battery connection cannot then damage your

But you MUST have a fuse in the negative lead if you
connect your negative lead *directly* to the battery.
Ham equipment comes with the fuse, because they
assume the ham might connect it that way.

A pro installer would never do that.


  I don't remember a single case of a destroyed radio or fire in a vehicle.  Kenwood about 15 years ago included a fuse in the negative lead, but before that no one seemed to worry about the "Floating Ground".  Has the automotive industry just gotten sloppy or what is the difference?  Today many cars and trucks have a heavy ground to the engine block and a light wire to the body.  Radio shops always got + directly from the battery and negative from the metal case and a lead to the car frame (no fuse).  Today, most radio shops go to the fuse block and any convent metal dash support.

More information about the aprssig mailing list