My Icom radios come with the power cord fused for both negative and
positive. From what you say, I should remove the negative fuse if I install
the radios in a vehicle. Now when the radios are at the fixed station the
same power cord is used (both lines fused), I understand that the negative
line fuse should also be removed.
Doug
I wasn't born in Saskatchewan, but I got here as soon as I could.
-----Original Message-----
Any good connection to the chassis anywhere on a unibody vehicle is far
better than a connection to a battery negative. Motorola is smart enough to
tell installers to ground to the chassis, not the battery. In the UK the
directive is to use the chassis or a manufacturer supplied terminal, and it
specifically prohibits connecting to the battery negative pole.
The negative fuse is just foolishness. If it opens, all the radio current
goes through small wiring. If the fuse opens, there goes the radio or
something connected to the radio via a port. All of the radio current will
go through some small wire.
My shop bench radio has an open foil on the CW key line and the mic because
of a fuse holder failure, and that isn't the first radio that has that
happen. :)
The entire problem centers around use of the battery pole or battery
connector as a source, and this carries over into our station desks. There
is a ground loop similar to that in a car created between the power line
ground, the power supply case, the negative lead, and the radio chassis back
to ground. As in the car, if this stuff was built or wired correctly, the
12V bus would only be grounded at one point and there would be no negative
fuse.
In our houses, many of the problems blamed on RF feedback are actually
ground loops caused by grounded cabinets common to negatives and voltage
drops on negative leads.
At least some places in Europe got their together and banned battery
negative connections because of the hazards.
73 Tom
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