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RE: Inquiry



Got a local HAM here in El Paso who used to do RF testing
for GM products about a year ago.  If anybody is really
interested, I can see if he is willing to answer any
questions.  He is still with GM, but doing Y2K stuff now.


Y-all have a great evening,

Vy73,  Mike.   KD9KC    MARS: AAV6EV
kd9kc@elp.rr.com  -  kd9kc@amsat.org
Home page: http://www.qsl.net/kd9kc/
The farthest WEST ham in West Texas.
 
El Paso, where we have two seasons;
Summer, and Christmas.


> -----Original Message-----
> From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
> Behalf Of Mark Johns
> Sent: Monday, April 26, 1999 2:24 PM
> To: Roy Welch
> Cc: amsat-bb@AMSAT.Org
> Subject: Re: [amsat-bb] Inquiry
> 
> 
> 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
> IN PASSENGER COMPARTMENT."
>     * 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
> characteristics.
>     * 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!
> --
> Mark D. Johns, Cedar Falls, Iowa -- K0MDJ (EN32sm)
>  "Heaven goes by favour.  If it went by merit, you would
>     stay out and your dog would go in." -- Mark Twain
> 
> 
> 
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