On Thu, 15 Jul 2004 19:41:14 -0400, "Finch" wrote:


"Diverd4777" wrote in message
...

Finch:

the best way to figure out what works best is try a bunch of different
configurations,
taking the car / SWR on a small test drive at the same timne of day (
Night)
check each one out..

& then make notes, so you can accuratly compare each configuration &
subsequent performance


Hey Dan,
I agree with your approach. Research and trial and error are the best way
to really figure it out.
I like an experimant as well as the next person.
However, as my time is short, I had hoped to just get an answer as to what
is really best.
Your point is well taken.

Thanks and peace,


Hi OM,

Your wire sharing the same length of car antenna is OK. However, use
insulated wire so that the two radios (yours and the wife's) don't
make their own arbitrary DC circuit (especially if you plan to power
your radio off the car's battery).

Further, your idea of using coax to go from the base of the car's
antenna back into the cab is fine. In fact extend that idea and
simple strip the coax cable down to its inner conductor and use THAT
to mount to the car antenna. Then you don't have to solder anything,
and you have insulated wire from the git-go and shielded wire back
into the cab. Make sure your coax shield doesn't accidentally touch
the car's antenna though. If this sounds like too thick a wire, use
RG-174 which is quite skinny (0.125" OD) and the inner conductor even
smaller. Wrap the inner conductor (or any wire arrangement) around
the car antenna at about one turn for every inch it climbs. This will
make for a loose spiral wrap, but give you a little more exposed
antenna for your set.

And yes. test. You don't want to drive 500 miles listening to the
spark plugs. If this happens, you may need to insure you find ground
for your set to actually turn that shield into something effective.
If that helps, but doesn't completely do the job, you may need to pass
the shielded lead through a ferrite core several times (RG-174 does
this great). If your hear alternator whine, you may need an
automotive power filter. Radio Shack sells them with big hurkin'
coils for big hurkin' current. Your radio will hardly need that much
current, so you can use larger (more inductance but less current
capacity) coils to more effectively suppress the whine.

73's
Richard Clark, KB7QHC