[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

RE: Inquiry

Thanks for the replies to my inquiry regarding auto systems RF
interference.  For the info of others, here are the replies I received.

73, Roy

Internet: w0sl@amsat.org
Home Page: http://home.swbell.net/rdwelch

Contact Ford Technical Support directly,
your local service advisor should have the info handy on install
ing radio transmitting equipment in their product.
all car lines have these instructions. sometimes specific filtering
connecting instructions.

Motorola has a short enclosure to their manuals that instructs the
installer on how to determine if there is interferemce between the newly
installed radio and the car systems.

The instructions cover such things as radio and antenna placement to
minimize interferance and the use of two people during the checkout

This past weekend I took my 2 meter (50W output) rig with me in the
truck, and I had no problems at all.  Truck is a 1998 Toyota 4WD, the
ICOM was sitting on the passangers seat, I know, very unsafe, and the
power cord was plugged into a power socket in the cab.  My antenns was a
magnetic roof mount.  The Truck has both the Airbag system and ABS
Braking system.  As I said, no problems at all!  Nor have I heard of any
problems with regards to RF radiation.  Good Luck.

Well, I just tried the impirical approach. I survived the installation/use
of a 50w rig powered via cigarette lighter in a new taurus.

   I just put a 50 watt rig (a couple of months ago) in a 1999 Pontiac, and
had the
same worries.  I would assume Ford will make the same kind of info
available as GM.
My starting point was


Hopefully it will be helpful to use as well.

Sorry I don't have anything on Fords, Roy, but GM and
Chrysler both had large displays at Dayton last year and I
picked up flyers from them.  The high points:
    * Both GM & Chrysler seem more concerned about physical
mounting than RF -- they caution to keep the installation
away from anyplace near where an airbag will be deploying,
and also caution about not having mics or other accessories
becoming missles propelled at you by a deploying airbag.
Likewise, they want the radio bolted in a place where it
won't interfere with normal operation of the vehicle, and
mounted solidly enough that it won't become a projectile in
an accident.
    * Both GM & Chrysler recommend reference to ARRL
Handbook and other "standard references" for installing
power cables and antenna feedlines.  Ground leads are not to
be fused, but positive leads should be fused as close to the
battery as possible.  Both recommend getting your power
directly from the battery, not from anywhere in the
vehicle's electrical system.  GM is emphatic about grounding
ONLY at the battery, cautioning several times, "NO GROUNDING
    * Chrysler suggests running all cables "under the floor
mats, inside the corner where the floor pan mets the rocker
panel for best protection.  Remove the sill plates and tuck
the cable under the floor mats or carpet and padding."
Chrysler suggests all cabling go down the right side of the
vehicle.  GM suggests going down the driver's side, and even
if the battery is located on the right, to tap the battery,
cable across in front of the engine, and then down the left
side.  The only guideline either flyer gives about vehicle
electronics is "All attempts should be made to maintaint as
great a distance as possible between radio power leads and
vehicle electronic modules and wiring."  Neither of them
specifically tells you where this is in any given vehicle --
you have to look and see.
    * Both GM and Chrysler advise against mag mount or glass
mount antennas.  They want a solid electrical connection to
the car body at the antenna, and tell you that you can
always get a hole plug to put in the hole at trade-in time.
Both indicate that "Antenna location is the most important
consideration in any mobile installation."  GM shows center
roof and center trunk deck mounts in their diagram, as well
as a possible bumper mount on the LEFT rear (remember they
want everything down the left).  Chrysler suggests center of
the roof as best choice, center of trunk deck second choice,
and "follow manufacturer's instructions" for larger HF
antennas.  Chrysler specifically recommends NMO style mounts
for VHF and UHF antennas because of the grounding
    * Both GM and Chrysler are emphatic about using high
quality coax (RG-58) with at least 95% shield, and making
sure the shield is SOLDERED at the antenna mount and in the
UHF connector attached to the rig.  Both say that you should
be certain to keep SWR as low as possible.
    I am in my car over 3 hours a day and run 200 watts HF,
50 watts VHF/UHF, in a '96 Toyota Camry with no trouble at
all following these guidelines.  My VHF/UHF antenna is on an
NMO mount in center roof (I removed the dome light and
drilled up through the roof there.  My HF antenna is a trunk
lip mount on the left side.  I had to re-engineer the trunk
lip mount to get a good soldered ground connection -- some
manufacturers just squeeze the coax shield under a washer
and call it good.  I also use a modified aviation headset
with boom mic so that I can keep both hands on the wheel and
use VOX on HF.  I strongly suggest this, as holding a mic
for long QSOs is as bad as holding a cell phone in traffic.
I get some funny looks, but I haven't hit anything!
    Have fun and good luck!
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org