Ham Radio Installations & Question

[GBurton]

Since there are a few of us Duramax owners who also share the hobby of Ham Radio. I am starting this as a place to exchange information concerning Ham radio installations and operating in this series of truck.

My installation consists of an IC-706 HF/VHF/UHF radio and a Kenwood DM-700 VHF/UHF radio. Both radios are located under the rear seat with the remote mount control heads. The control head for the IC-706 is mounted on the front of the door to the storage bin on the vertical part center console. The control head for the DM-700 is mounted to the dash to the right of the steering wheel. I considered mounting one of them to the blank panel in the overhead console but I was concerned about trying to read it at an angle from the drivers seat.
The HF port on the IC-706 is connector to a diplexer; one port is connected to a 6-meter antenna in the center of the roof. The 30MHz and below port is connected to a High Sierra HF Screwdriver antenna mounted to the front of the bed, on the drivers side. The VHF/UHF port is connected to a VHF/UHF antenna that is located on the roof but towards one side.
The DM-700 VHF/UHF (APRS) radio is connected to a second VHF/UHF antenna that is also on the roof but on the opposite side from the first VHF/UHF antenna.
The GPS antenna is a magnetic mount antenna located on the rear driver

[LarryM]

Hi george,

We've talked about this problem before, but I may have some additional info.

My prefered mounting location for HF antennas is on the front bumper for pickups and vans. This keeps the large HF antenna out of the way of the load/trailer.

On my 2500HD, I have tried my usual front bumper mount, as well as the headache rack, Gooseneck ball socket, and lastly, the left rear corner of the cab high camper shell.

I usually run an IC706 on 17 or 40. The injector noise seems to peak on 17 and is much less on 40/75. With the antenna on the front or the headache rack, the noise makes 17 unuseable and all the other bands pretty poor. Moving back to the camper corner dropped the noise level at least 10 dB and the built-in NB and DSP actually work.

There is no way I'm going into the wiring harness to experiment with filters, etc., so this is an acceptable solution for me. I can't have an antenna when I'm pulling a gooseneck, but I don't have time to play with the radio anyway when I'm doing that. Running with just the camper or even with a tag-along trailer, there is no problem.

Other experiments have proved to me that the noise is NOT coming in on the power leads or the coax shield. It is definitly radiated. I tried with little luck to use an MFJ noise canceller to null it out, but didn't have the time to set it up properly. I expect I could design and build a proper phasing unit and completely null out the injector noise but that would only be a single band solution.

If GM cares as much about the noise in this truck as they did in my other trucks, you will get little more than a raised index finger from them.

Lastly, with the antenna on the rear mount, I have no probelm with RF getting into the trucks systems on any band.

[Chris N5CWM]

Good topic! I'll chime in even though I have my
mobile in a D*dge. ;)

I have a Kenwood TM-D700 APRS radio as well, and use
a Garmin GPSIII mounted on the dash so I can see the
screens, which include a map mode. Comes in handy
quite often.

Next radio will be an Icom 706. I plan on installing
a headache rack and mounting the antennas there. I'm
currently using a 2m/70cm Larsen on an NMO L-bracket
attatched to the right forward side of the bed on the
bedrail. I don't want to drill into my roof which
would be the best place RF wise, but I've seen too
many really messed up roofs when they forget and
drive into a low parking garage, or when the
antenna mount starts leaking after an unknown
period of time.

Here's the URL to the N5CWM Ham Radio site. Just
some of my personal links and stuff, nothing fancy.

http://n5cwm.dynip.com/

I have a Kenwood TM742 tri-bander 6m/2m/70cm radio
that I plan on installing in the Yukon XL soon. It
has been out of use for a couple years but somehow
the control head frequency tuning knob is not
working. I can use the UP/DN buttons on the mic but
that is a major pain ITA! :D Gotta send if off,
I hate doing that. :rolleyes: I'll probably get
an FCC Mandated CPU change since my radio currently
will tune into the cellular band. Of course at the
time that was not "illegal". That is why I'm
procrastinating sending it off. Hmmmm.

Here is a pic of the GPS & TM-D700:

http://n5cwm.dynip.com/ram2500-hamradio.jpg

And a pic of the Cummins Powered APRS tracker:

http://n5cwm.dynip.com/ram2500-2k1-124.jpg

-Chris

[ 07-25-2002: Message edited by: Chris N5CWM ]</p>

[Dave_WB3FYV]

Lottsa plans, limited time to implement, everything temporary!!!

Currenty have a first generation IC-706 mounted under the dash in front of my right knee with plans to mount the control head on the CD storage door and then move the main unit either into the console or under a seat.
Kenwood VHF, KPC-3 tnc for APRS, and a wide-band scanner are all stuffed into the center console, commuications speaker in the rear seat cupholder. The scanner will be moved into the front panel of the overhead console where 'normal' people mount EGT and Boost gauges. Would have put another VHF radio there but didn't want the dangling mic cord blocking the mirror, so will probably just rely on the 706 for all voice commuication.
Ancient Garmin-45 GPS hides in the console with everyting else until now that the magnetic hockey-puck external antenna died, so I have to figure out what to do next. There's only one local digipeater so coverage is spotty and I haven't been in a hurry to fix the tracker. VHF radio and TNC will stay in the console, outta sight / outta mind.
Dual-band mag mount antenna on the roof serves the scanner right now, gets switched to the VHF when I want the tracker on line. Coax routed in through the bottom of the rear door jamb, probably get moved to the cab vent hole.
HF antenna is a KJ7U screwdriver type (6m thru 160m) mounted to the back of a metal toolbox in the bed on the drivers side. I lift and rotate the toolbox so it's lengthwise against the drivers side rear wheel well, antenna in the space just in front of it so a morotcycle can slide in along the other side of the shortbed. For this to work it requires a massive ground cable and clean connection to the metal of the bed. Still get some RF into the truck radio. Coax and power for it run thru one of the bed drain holes, under the truck, then in thru the grommet for the shifter cable under the drivers feet and up under the dash. There's a Channel moulded into the floorboard to keep the cable from making a bump under the carpet. Up/Down control switch mounted to the side of the radio, but I plan to replace it with 2 momentary pushbuttons for better control. No VHF antenna on the 706 at present, but plan to make a bracket and mount one to the inside of the DS front fender near the windshield/fender/hood junction ala Mdrag. (check HIS pictures for some really slick radio mounting ideas! as long as you're willing to sacrafice the cassette player)
Power for the 706 comes thru the firewall, through the grommet for the hood release cable and direct to the battery jump-start point. The VHF and TNC are just plugged into the cigar lighter port.
If I get the nerve, I'll drill a hole in the roof for a multi-band antenna when I have the console down mounting the scanner. Sheetmetal up there is really this, probably not stiff enuf to handle one of the long multiband hi-gain sticks.
I might try to move the HF antenna onto a trailer ball mount, run the cables under the truck to the back bumper. Another screwdriver antenna I have mounted to my travel trailer's rear bumper can be used when towing it, definately cut down on the receiver noise!!!. Just slide out the antenna/hitch, slide in the ball mount, swap cables and I'm in bussiness! I'll lose the use of 6m and 160m while towing the trailer, but I can sacrafice that much.

LarryM, do you still hear the noise with the antenna mounted on the back of your camper shell?

Noise coming in on 14mhz and above is a concern, and I have no solution at this time. Originally I thought it was just the lousy noise blanker in the old 706, it was never noted for it's efectiveness - but the new models don't sound much better. Would like to try a Yaesu FT-100, another ham I know has one is his F350 diesel, says its quiet but I don't know if it's radio or truck design.

I just hate drilling into a new truck, that's why things are this way. Time to bite the bullet.

[LarryM]

Dave,

The noise is still there with the antenna mounted in the back. It is, however, much reduced in level. On 20 - 160, the noise is usually buried under band noise if the band in question is actaually open and useable. 17 meters and up is a different story. The band noise on the higher bands is much lower and so you can always hear the injectors banging away.

FWIW, the injector noise on our '90 Astro van with a front mount antenna is about the same level as the D-max with a rear mount even though the Astro is a 4.3L gasser. On my old K2500 5.7 L gasser, I gave up mobile because the noise was very bad no matter where I mounted the antenna.

The solution is to go back to the old style mechanical pumps and injectors and have no on board electronics except your radios!

BTW, my call is W7IUV. Do a Google search on my call, I have some stuff on the Web.

[Bud]

I enjoyed this information. I also have the IC706M3 unit in my truck. When I learn how to use this form I will submit my set up.
For a start see my Home Page

http://www.cableone.net/n7xs

Thanks
Bud N7XS

[ 08-13-2002: Message edited by: Bud ]</p>

[Tom Ellis]

Here is my set up.
ICOM IC-706 mk11 remote head mounted to the Left of the steering wheel. Kenwood TM-742A (144,220,440 MHz), Standard Commercial radio, and Yeasu/KPC-3 combination mounted in custom verticle frame in center console area. I do not have the center console. I have a screw driver antenna for the 706 mounted off of the trailer hitch with a custom hinge, so I can have it either out the side of the truck or out the back driver side of the truck. The antennas for the 742, SAR radio, and the vhf side of the 706 radio are mounted on the roof. The APRS antenna is mounted on the side of the hood.
I installed clamp on ferrite cores on the remote cable for the 706 at both radio and head.
I installed an Optima Yellow Top aux. battery with a Sure Power isolater. This runs all of the radios.
At this time, I do not get any noise that is bad, I do get a little noise on VHF and some on HF (15 meters)when the band is quiet. Otherwise, no noise.
Thanks for starting this thread.
Tom Ellis
K5TEE
:eek:

[Dave_WB3FYV]

Jump in here Bud, and welcome to the forum. Tell us what you have, seems like the 706 series is the rig of choice so far. Antenna location is the fun part! Not too many places to mount the radio...

So based on what LarryM said, I won't bother moving my HF antenna out of the bed. It's too well protected from damage and theft in there - and if the noise is the same...
One good thing I did this weekend was run some more #12 wire from the base plate mounting the antenna to the toolbox (nice clean connections) tied the braid from the coax to it, down thru the bed drain hole to the factory installed braid that ties the bed to the front of the truck on the drivers side. Stumbled on this connection, but it's the ideal spot for antenna grounds. Made a major improvement across all bands. Receiver is quieter, but RF still gets into the stereo amplifier. When I first tried tuning after hooking everything up, it didn't squeal at all !!! Then I realized I had the door open for so long the automatic power-down circuit had cut off the dome lights, and apparently the stereo. Now I gotta find that wire and put a switch in line, I'm willing to have one radio or the other if I can get rid of the feedback so easily! The clock stays on so it doesn't completely disconnect the radio power. Anybody know which wire to cut?
Then, I mounted the control head for the 706 on a short Panavise adaptor, drilled a couple holes in the cupholder insert and voila! Easy to use radio again smile.gif Antenna tunes 20, 15, 10, and 6 meters in a very narrow area on the coil, so I can scan 29.660, 53.170, and 14.3025 without retuning and minimal tweaking to transmit!
There isn't much room in the overhead console for a scanner, at least not deep enough for the one I have. Back to plan B.
Routed the coax for the magmount dualbander down the back of the back door weatherstripping, under the door sill plate, under the carpet with the HF feed to the 706. Antenna now sits at the back edge of the roof on the drivers side. Much cleaner installation.

I gotta get some pictures on the 'net soon.
:D :D :D