Butch Davis wrote:

What are the ramifications of shortening the cable by cutting and spliceing?
I've heard conflicting advice.


The GPS antenna cables are not "tuned" to length. A shorter cable
should give you less attenuation loss.

Meticulous work, attention to detail on cutting and trimming lengths,
careful soldering and crimping, all add up to good low loss cabling. In
recent years I started using a length of the adhesive lined shrink tube
about twice the length of the crimp sleeve over the sleeve and coax and
that really makes a nice sealed joint.

If you have to do a mid cable joint to accomplish a cable run, use
dielectic compound on it and seal it with heat shrink (use the non
adhesive if you think you want to get at it from time to time). You'll
lose about 1dB for each fitting, maybe 3dB for something like two BNC's
joined with a barrel.

Powered antennas will have a positive voltage on the center conductor
that is returned to ground via the shield. If you want to make sure
that is not inadvertently shunted to ground somewhere along the run, use
tape or shrink tube on any exposed connectors. You can usually use a VOM
on a coax connector to tell if an antenna is powered or not.

Not all powered antennas use the same voltage, it might be 3.3V or 5V in
my experience, I don't think I've never seen 12V on a GPS antenna though.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)