[Icom] Mobile Noise Supression - Final Chapter

Tue, 8 Oct 2002 22:14:01 -0400

Doug,
   I had a similar problem on a Chevy 1500 96 Pickup.   It wasn't there
when I first got it (company vehicle), but I put about 50,000 a year on
it (had over 80k when I acquired it), and after 3 years, HF was not
useable unless the station I tried working was a S9 or stronger signal
from 10 meters down.  Two meters had limited hearing range because of the
noise, the S meter on my IC3200 ran about a S6-7 on 2 meters.   The FM
stereo radio was too noisy to enjoy unless I was within 25 miles or so of
the station.  Then I started have the 706 do stupid things, I'd be
talking along, and it would reset itself, then one morning I couldn't get
it to turn on.   I had the positive 12v lead going straight to the
battery, but the ground was going to the frame at the front door.  
Imagine my suprise to find I had about 9 volts across the 706 leads.  
Went to the battery, had 14.4 volts (with engine running, both
measurements).   It took me a half hour or so to determine that I had
shook the frame so much on the road (part of it is getting to moutain top
sites to service paging systems on trails), that I was loosing about a
volt per  foot of frame.   I ended up having to do the possitive and
negative leads directly to the battery leads, but couldn't get rid of the
noise.   If it was setting still, it wasn't bad, but the faster I drove,
the higher the noise level, even on 2 meters, and on the FM stereo radio.
   Trying to find the resistive spots with an ohm meter, even on a 1 ohm
scale was an exercise in futility, but pulling current throught the frame
made it very easy to see the voltagae drops from point to point.   At the
end when it didn't want to turn on, just the 706 in receive was showing
the drop from 14.4 to 9 volts.   Truck started giving me major and
expenseive problems, and was able to trade out with another service truck
in the pool   My 706Mk2 has worked flawlessly ever since.

73's de Stephen, K0SD in NC

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On Tue, 8 Oct 2002 13:20:12 -0700 "Davies, Doug A FOR:EX"
<[email protected]> writes:
> As some of you may remember, back in August I posted a plea for help 
> to
> solve the vehicle noise problem(s) with my IC-706MKIIG installation 
> a 2001
> Toyota Tacoma V-6 pickup.  I thought I would post a follow-up, for 
> those
> that may be interested.
> 
> From all of the replies I received, I tried out all of the 
> suggestions to
> solve the problem(s).  To date, these have included:
> 
> Power to rig goes directly to battery with fuses in both lines, both 
> lines
> have snap-on ferrite beads.
> Bonded all body parts to the frame
> Bonded engine block to the frame
> Bonded exhaust pipe to the frame
> Put large value cap (40,000uF@100V) across alternator terminals.
> Put filter in pos. alternator line
> Put filters in both lines of the fuel pump
> Put large snap-on ferrite bead on wire bundle exiting main computer.
> Put snap-on ferrite beads on both ends of antenna coax.
> Put ferrite beads on both ends of antenna adjustment power cable.
> Checked that spark plug wires are silicon low emmision type - they 
> are
> Checked that plugs are resistive type - they are.
> Went to Toyota dealer and asked if they could help me troubleshoot - 
> they
> basically told me to "stuff it".
> 
> So, the bottom line here is I've given up.  As I see it I have three
> choices, put up with the constant S-7 noise level, pull over and 
> stop if I
> want to have a QSO or tear out the whole damn installation and sell 
> the
> equipment.  I have run out of ideas and suggestions to try.  If some 
> has or
> knows someone who has a similar installation in a Toyota, and they 
> have
> solved the noise problem, please let me know how it was done.  
> 
> And, If you are considering operating mobile in that new vehicle 
> you're
> planning to buy, don't buy a Toyota pickup.
> 
> Doug  VA7DD 
> 
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