[aprssig] Mounting 2M Xcvr in '05 Toyota Camry

[Dave Baxter]

Hi...

As an EMC type, and a QRO RF technician, plus knowing more about some
vehicle electrics than I care to admit, I say this...

If you get *Any* "odd" behaviour of the car when transmitting, either
stop transmitting or reduce power levels till the "Odd" behaviour goes
away.  Then, at the earliest possibility, review the radio installation
to keep RF away from whatever vehicle system was affected.  Until such
time, do not use the radio at those power levels, or at all, if the
problem is really bad.

You are unlikely to "Fry" a car's electrics, or (any of the many)
computers, but you could in extreme cases cause the engine management to
go funny, or cut the motor if it gets really upset.  The worst could be
that you are left stranded with a fault light on, and being unable to
restart the engine until a dealer or other techie type resets the
management fault log.

That is for any vehicle, petrol(gas) or diesel with a fly-by-wire
engine, as most are built nowadays.  Such problems as your dealer says,
if attributed to your after marked radio installation are unlikely to be
covered by the makers (dealers, or third party) warranty scheme.

The usual things that can happen, are indicators flashing too fast, or
not at all in the presence of high levels of RF, false indications of
engine revs or other information, and things like wipers, window or seat
controls not working as intended.  Not usually a safety critical
problem, but the distraction it can cause can be a safety issue.

You are more likely to suffer higher than expected levels of QRM from
the car, to the radio on RX, than cause the car problems.  Particularly
bad, are some common rail diesel engines, as the injectors use a high
voltage to operate, and the SMPS in the management box, can radiate
somewhat on HF.  In EMC terms, things don't radiate much (if at all)
below 30MHz, but there again, those test limits are set to protect
broadcast signals, not the low level comms stuff we are interested in.

As has all been discussed at length here and on other lists, take great
care with the DC power feed, and RF grounding.  In particular, if you
run the -ve lead for the radio direct from the battery, fuse it!  You
wouldn't be the first to melt a radio or accessories when starting the
engine if the normal battery ground strap is anything less than
perfect...

Take care..

Dave G0WBX.