Your SWR is high. High SWR isn't responsible for whine, but it is a good
indicator of other problems. From what you said in your other post your
cab roof
is fiberglass, so you don't have any ground plane -at all- for your
antenna. But
even that isn't responsible for the whine. I suspect that the radio isn't
very
well grounded. The mounting bracket should be bolted directly to the dash
or
some other chassis metal, and the negative power lead should be as short
as
possible (inches) to the same. You can also try a noise filter on your
positive
power lead, and tap the wire as close to the radio as possible. That
should
eliminate your whine. It should also get your SWR down below 3.

As for your antenna, you need to find a point on the rig where the antenna
can
be mounted directly to the chassis. A mirror mount is ok if the bracket
and door
are well grounded. A 9' whip on the front bumper isn't a bad choice either
(don't forget to tie it back a bit so it doesn't flop around). You could
also
try one of those 'no-ground-plane' antennas but don't expect great
results. Ask
around the watering holes and see what others have done.




I thought that because the whine went away when I disconnected the coax that
the problem was not related to the power supply and one of those noise
filters would not be of much use.
My biggest obstacle is that this is a company truck. The CB, radio and TV
are all using these antennas thru some kind of combiner. Running new coax
would mean drilling holes in the cab. I am not sure how my boss would feel
about this. If it were my truck I would rip it all out and start from
scratch but I must do the best I can with what I have.
The antennas are mirror mounts. I have been reading about grounding. I
thought that two antennas actually were better on the fiberglass vehicles
because they could create a ground plane between each other. My antennas use
a plastic insert to keep them from being grounded to the mirrors. If I
ground them would this short out the transmitter?

I appreciate your feedback Frank, I know that it is difficult to diagnose
something from a distance but I am willing to try anything except routing
new coax.