[50mhz] Re: [Yaesu] RFI and car computer

[Robert Meier]

John,

AA5JG> We just bought a new (to us) 2007 Chrysler Town and Country Minivan.
AA5JG> The salesman went over the fact that the van has a computer in it
AA5JG> a couple of times.  Has anyone had problems with their rig affecting
AA5JG> the on-board vehicle computer?  This is not the on-star or GPS computer,
AA5JG> [but the one] which runs the vehicle.  I would be mainly going mobile
AA5JG> on 6m at around 35 watts or so on SSB and CW.

WB5ITT> ... but any signal on 20 out of the mobile would
WB5ITT> KILL the engine dead in its tracks! ...

KB6BSN> ... Next to the radio I have an LC filter. ...

KM1H> ... Dodge full size vans and Chargers are used by police and the vans
KM1H> as airport limos, and other commercial users with 2 way radios. ...

K8CM> As I recall, Chrysler had some pretty specific guidelines and 
K8CM> distributed them via the Internet, Chrysler dealers, and ham-related 
K8CM> gatherings.,  If your local dealer doesn't appear to know what you're 
K8CM> talking about, contact Chrysler's district office.

As has been pointed out, RFI from a mobile transmitter, received by an
automobile computer can KILL an engine.

Worse, it can leave one with a false sense of security, as the engine
doesn't stop, but the RFI distorts timing and control enough to
impair performance or shorten engine longevity to months or a few
years.

As also pointed out, filters are the typical solution.

Though I have a hardcopy, I couldn't find the Chrysler service bulletin
on Chrylser's website.  I believe you can find a copy at
http://www.cot.net/~n6mrx/ares/mobile.htm



As "electronic ignition" and computers were introduced into cars in the
80s, reputable transmitter installers (including myself) included filters
in police/fire/emergency and airport/private/commercial vehicles.
Though usually credited to purchase of a "lemon", at hamfests and fly-ins,
I heard disproportionately more stories of automobile woes from those who
connected directly to batteries.

In the 80s and 90s, installing filters used to involve improvising to
keep the filter close to the radio, properly fused, and non-interfering
with vents, cables, and everything else behind the dash.
In 2001, when I was looking at cars, most seemed to be factory-equipped
with at least one filtered accessory jack marked for cell-phone
(or power-inverter) use.  (I suspect this was self-protection as
warranties increased in coverage and duration).
Though the car I purchased did not come with a filter, the service
manual pointed me to a cavity, immediately below the accessory jack,
with connectors already crimped into the wiring.

Last year, I pointed a friend at a filter available from AutoZone.

Consequently, if you consult the service manual, you may find a
filter already in place.  If not, check your local auto supply houses,
and you should be able to install a filter yourself. 



The salesmen with whom I've dealt have had no understanding of the risks
of RFI.  In the last decade, most of the mechanics shops I've dealt with,
are aware of RFI risk.  For liability reasons, such shops have refused to
install a transmitter.  Such shops have known how to gracefully disconnect
them (if necessary for service), and though they would not reconnect
a non-factory transmitter supply, they were happy to refer a professional
installer.

73,
-- 
AA9AU
Bob

  "If an elderly but distinguished scientist says that something is possible,
   he is almost certainly right;
   but if he says that it is impossible, he is very probably wrong."
     -- Arthur C. Clarke