Getting RF on HF Mobil into the truck

Discussion in 'On the Road' started by W9KJO, Jul 21, 2020.

ad: L-HROutlet
ad: l-rl
ad: abrind-2
ad: Left-2
ad: Subscribe
ad: L-MFJ
ad: Left-3
  1. W9KJO

    W9KJO Premium Subscriber QRZ Page


    I have a 2017 GMC 2500HD. I installed a IC706MKIIG and a little Tar Heel antenna. The antenna is mounted to the back of the bed with a Ham Stick swivel mount. I have an Aux Battery with torroids in the DC feed and the battery is only for the rigs. I have ground flat strap on the exhaust, to the case of the truck computer under the hood, on the hood, and to the bracket for the antenna.

    When I key up on almost any band all the warning lights turn on on the dash. Even at a low 50 watts.

    this truck install has been very difficult. This setup worked great in my old 1998 Expedition, but this newer truck is difficult.

    any advice will be greatly appreciated.

    Walter, W9KJO
  2. KC0LDH

    KC0LDH Premium Subscriber QRZ Page

    Walter, I'm sorry you have having trouble.

    I do not have any first hand experience with the GM/Chevy products, but would start with the Mfr. Body-Builder manuals. They may have some precautions, details or other instructions how to install accessory 12v, or radio systems. I'm sure that the truck is used in Police, EMS, or similar duty's so there is something to relate to. At the very least, its got some good information for how the thing is wired, and is supposed to work. 5W4 Specification Guide 2017.pdf
    K0UO likes this.
  3. KC0LDH

    KC0LDH Premium Subscriber QRZ Page

  4. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    I feel your pain I went from an 08 GMC Duramax to a 2017 Chevy Duramax three quarter ton. I also have an install in a 2015 Chevy Duramax
    When I'm using HF even my ABS brakes would lock up/ quite scary

    When I first installed my truck even shut down a couple of times also airbag warning light also very scary.
    After several years of adding grounding straps everywhere probably 50 feet and close to 30 or 40 toroids (which I'm not sure all the toroids) have really done that much good, I am finally able to operate with only a few problems even while running the AL500

    And don't blame Chevy/GMC, my son's F-350 Ford has done the same thing/ warning lights and RFI.

    The Good thing is that GM has really cleaned up the RFI coming out of the trucks system, I hardly detect any on any of the low-band frequencies.
    The Ford has terrible IFR coming off of computers and injection systems.

    I suggest you go to Alan's Applebee's site
    He has information about installs using Tar H and the other screwdriver, it is an absolute must read for any install, you may not have even connected your power lead properly charging your other battery, all new vehicles have sensors on the power leads coming off the battery.

    All new vehicles are extremely hard to get HF to work but you will make it happen with some preservation.
    If you haven't already done it, it is an absolute necessary to ground the bed to the frame in all four corners with straps, the mount, and the tailpipe muffler system in probably three or four places, even a hood needs a ground strap (not just a wire). Make sure you grind down to bare metal and put appropriate coating on the connections the frames are coated with insulated material.
    I don't know how you have mounted the Tarheel I'm using a similar antenna the Scorpion/ posts some photos
    Read Alan's site

    Keep us posted a Good HF Mobile is worth it
    Last edited: Jul 21, 2020
    AA5LS likes this.
  5. KD7CFM

    KD7CFM Ham Member QRZ Page

    I have put 50' of 1" ground strap between every body panel and the Frame. The exhaust and core support are bonded, too.
    I have the chokes installed on the incoming coax, the screwdriver power and mag switch. Per K0bg.
    On 20m above 50W the windshield wipers swipe while xmitting. Even after shielding the control box and grounding it, too.
    On 15m the S meter on my 11m radio will go crazy even when it is powered off.
    Everything else works. I will put a toggle switch on the wiper power lead if I can't cure it.
    90 Dodge with FT-991a and Little Tarheel II HP.
    K0UO likes this.
  6. AC4RX

    AC4RX Ham Member QRZ Page

    I have a 2015 2500 HD Silverado, I installed a TS-50 with a screwdriver antenna. My only problem was an awful alternator whine. I went straight to the battery with stranded number 10 wire, added a Power Communicating Module model PCM-25ADL. It did reduce the whine to an acceptable level, but still not quite enough for my OLD ears! I have never encountered all the other symptoms mentioned in this article.
  7. AK4OC

    AK4OC XML Subscriber QRZ Page

    have you resolved your issue? i feel like i have had a fairly successful install on a 2015 silverado. IS yours gas or diesel? what is a swivel mount? how about some pics of the install.
  8. AA5LS

    AA5LS Ham Member QRZ Page

    I also have a 2017 GMC 2500HD, been an avid hf mobiler for over 40 years.
    When I first installed my FT857D and a hf antenna, on 40 meters it set off the traction control, disabled the cruise and other problems.

    Well after year of problems, decided that I was going to fix it one way or another. I am retired from working 45 years in GM car and truck dealerships, I have worked about ever job there is in one except owning the dang place, started in detail, mechanic, parts, parts manager, service manager, sales for ten years. final comtroller.

    The fix, proper installation of radio, antenna, and grounding. The problem was resolved when I added proper rf grounding to the antenna. There is a difference between rf ground and dc ground. This can be debated with no winners, but there is a difference. Also a ground loop from the antenna through the coax will cause these problems encountered. I eliminated the ground loop on the coax with a rf choke of 8 turns of coax in a 6 in coil at the feed point of the antenna.

    Power feed on late model vehicles is important. The ground cable to the radio must go through the hall effect sensor around the ground cable for the charge system to work properly if the ground cable is connected to the negative post on the battery for the electrical system to charge correctly.

    Ground all body panels to the frame multiple times.I installed twenty ground straps. Ground the exhaust system in several places to the frame. Ground the hood to the fenders and cab. Body grounding accomplishes two thing, one it reduces noise the receiver picks up that is generated in the vehicle. Two, it make a larger capacity plate to mother earth which is the second half of the antenna on lower hf bands(40 and 75 meters), this reduces the ground loss part in the antenna system. Study the components of a ground mounted vertical antenna, ground loss, feed point impedance, coil loss.

    Ground Straps. Proper ground straps are important to get an rf ground. A piece of wire will dc ground but does not always provide an rf ground. There is plenty of material on the web on proper ground straps an correct way to install them so rf flow on the strap with little to no impedance. If the ground strap has impedance at the radio frequency used it is of no use.

    The antenna must be properly rf grounded, rf loop removed from coax, and feed point impedance matched. If feed point impedance is not matched, you do not get 100 percent power transfer from coax to antenna, this also results in swr that plays heck with the on board electronics of the vehicle.

    I have done this on several vehicle I have owned. I got lazy when I first bought this 2017 GMC2500HD, but when I got off my lazy butt and started proper mobile installation, problem was solved.

    There is plenty of out there to study what to do correct problems like this. I am not an electrical engineer, my degree is in mechanical technology, but I have learned to research out my problem, and study what it takes to make it work. I have found that there are many old books on ham radio are still good places to learn antenna theory and grounding.
    K0UO and KB3UWC like this.
  9. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    That's a very good overview, I have 3 Late Model Duramax Chevys and I agree with all your info. I have also had some problems with the anti-lock brake system/ on one vehicle is totally locked up the system/ which was quite alarming when you're going down the road at 70 mile an hour pulling a trailer!!

Share This Page