Scott wrote:
Anybody have any ideas to lower noise in my FT-857 mounted in my F-150
pickup? S7-S9 noise (engine running, with NB ON) on 17M (Only band I've
tried on HF yet). Antenna is an Outbacker mounted on a mount I welded up
for my receiver hitch and puts the base of the antenna at about roof level.
Quiet as a mouse when truck is shut off. Go figure...hard to be "mobile"
with the engine off 
--
Scott N0EDV
Gotta Fly or Gonna Die
http://corbenflyer.tripod.com
Building RV-4
Excellent answers from others. I'll add that I faced and
fixed fuel pump the problem on my '91 Marquis - but that
was on 2 meters. Dunno if my fix would have prevented
the noise on HF as I didn't run HF mobile.
Anyway, I installed a BIG (physically) feed through
cap in the trunk in the + line to the pump. I also
installed a couple of .1 uf (as I recall they were
..1) caps - one across the power leads at the rig,
and one in the blower circuit. I was getting noise
from that too. That one was easy to isolate, as the
noise was there with the engine off and the vent/AC/heater
blower on.
My experience is not representative, and it was to
solve hash on my 2m/440 rig. A cap *in* the tank
should be more effective, in my view. But I figure
the more you know about these *()$%# noise problems,
the better off you are.