[VHFcontesting] RFI and car computer

[George Sintchak/WA2VNV]

John, get a 6M handi talkie (Icom T81, etc) and with the car running in 
normal operation, search around ALL the wiring, door, dash, trunk, engine, 
etc for Rx noise & interference on the bands you want operate. Keying the Tx 
will also show if in causes any malfunction of the cars systems. They have 
these little computer "boxes" hidden all over the car behind kick panels and 
in the trunk walls.

I use a Icom 706 mk2g in my 2000 Toyota, Avalon that has a severe buzzing 
noise on multiple frequencies on 144/432 coming from the computers behind 
the driver's side dash and the drivers door window control panel. I searched 
around with a pickup coil and my spectrum analyzer. No noise problems on HF 
bands with trunk lip ham sticks for 40 thru 10M.

I tried ferrite chokes, aluminum foil, even painted the inside of the 
plastic enclosures with RF absorbing shield paint. It just seems to radiate 
out through the "network" wiring that runs all over the insides. It's not 
getting into the radio via the radio cables  - if I unscrew the roof dual 
band antenna from the NMO mount, all the noise is gone - so it's radiated 
emissions - not conducted through the wiring into the radio. I contacted 
Toyota about the problem and no help from them - they are more concerned 
with your 100 watt radio messing up the anti-lock brakes and fuel injection 
computers, etc. After about 2 years of trying, I basically gave up, and 
learned to live with it using PL decode mode on repeaters and on some SSB 
frequencies, it's tolerable. So, be forewarned - YMMV. Good Luck.

George


----- Original Message ----- 
From: "John AA5JG" <aa5jg at lcisp.com>
To: <ft100 at yahoogroups.com>; <yaesu at mailman.qth.net>; 
<icom at mailman.qth.net>; <50mhz at mailman.qth.net>; 
<vhfcontesting at contesting.com>; <6meter at yahoogroups.com>
Cc: <nn9k at arrl.net>
Sent: Saturday, July 05, 2008 11:48 AM
Subject: [VHFcontesting] RFI and car computer


We just bought a new (to us) 2007 Chrysler Town and Country Minivan.  The 
salesman went over the fact that the van has a computer in it a couple of 
times.  Has anyone had problems with their rig affecting the on-board 
vehicle computer?  This is not the on-star or GPS computer, just the run 
which runs the vehicle.  I would be mainly going mobile on 6m at around 35 
watts or so on SSB and CW.

73s John AA5JG

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