HF operation from a Motor Home

Discussion in 'On the Road' started by K6PIJ, Feb 16, 2021.

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  1. K6PIJ

    K6PIJ Ham Member QRZ Page

    I have a 706 MK2 in my motorhome with a Tar Heal antenna mounted to the ladder rack. While the radio does work I find that I am not able to make many contacts. I suspect that since the body is all fiberglass there is no ground plane to reflect from. I have run braded copper strap from the antenna mount directly to the motor home frame and it didn't seem to help. Any suggestions or has anyone else found a suitable way to operate HF from a fiberglass motorhome?
     
  2. W2SGM

    W2SGM XML Subscriber QRZ Page

    Assuming it’s mounted on the top of the ladder rack, running radials along the roof is probably your best bet. You will need to set up poles around the RV to support the radials that can’t run along the roof, otherwise the antenna will be somewhat directional. What bands are you looking to work?
     
  3. KE0EYJ

    KE0EYJ Ham Member QRZ Page

    create 2 radials for each band you hope to work, and stretch them out as much as possible (preferably above or angled away from the fiberglass, and spread apart as much as you can). You can fan them out off of the back end of the motor home, and it'll have a lobe pointing in the direction of the back of your vehicle.

    2 x 15m radials each about 11 feet 8 inches
    2 x 17m radials each about 13 feet 7 inches
    2 x 20m radials each about 17 feet 6 inches

    And if you have space...
    2x40m radials about 35 feet 1 inch

    For fewer 'physical' radials, you can easily take a piece of speaker cable and trim one side wire for the 15m band length, and the other wire attached to it to 17m length, for example. Then do the same for 20m and 40m on another wire. Preferably you'd do that to 2 sides for each band/s.
     
    Last edited: Feb 16, 2021
  4. K6PIJ

    K6PIJ Ham Member QRZ Page

    The band that I am really interested in operating on is 80 meters. Not sure if this is going to work well for my situation. Running radials will be difficult. I am not interested in operating while mobile but stationary in a campground.
     
    WW2PT likes this.
  5. WW2PT

    WW2PT Ham Member QRZ Page

    If you’re not using the antenna while mobile, you could take it off the RV and mount it on a tripod with a bunch of short radials on the ground. I did this for years and worked a lot of DX. Tuned radials on 80m is going to be tricky if you’re in an RV park, I imagine, and they need to be elevated for optimum performance. When radials are on the ground, and in quantity, their length is less critical. At least that’s what The Experts say. In any case, I worked around 200 countries with a Tarheel 200A-HP on a tripod with one of their radial kits (9 ft x 10).

    18576DC7-F2B5-4F3F-AF8C-9A986B2E8CF2.jpeg 6F6DC30B-BF54-4AB0-A232-CFD83082ED96.jpeg 91A1AAC9-14A9-4769-AF7A-7DC1C4EB209C.jpeg
     
  6. K6PIJ

    K6PIJ Ham Member QRZ Page

    Thanks, nice set up. I may consider that.
     
  7. W2SGM

    W2SGM XML Subscriber QRZ Page

    When you set up your tripod, try four radials at 0.1 wavelength each. I think you’ll be surprised how far that will get you, and it won’t take you forever to pack it up and move elsewhere.
     
  8. W7HV

    W7HV Ham Member QRZ Page

    With my screwdriver, I used 8 ea 10' radials that I kept elevated off the ground by a few feet by holding them out with string/rope. It worked FB. I currently have it on the roof using 4 radials, 32', 16', 11' and 8' and it tunes 80 through 10. A few bands, including 80 have higher SWR, but still under 3 and tunable by the rig's ATU.
     
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    "Tarheel."

    Which model?

    For 80 meters, their model 100HP is really very good; the "Little Tarheels" and "Baby Tarheels," not so much. The 100HP is way better, and should work okay when parked (it's very long for driving along roads as it will hit a lot of low branches and stuff).

    The model Tarheel really matters quite a bit, especially on 80 meters.

    I had a 32' Class C motor home for years (built on an F450) and it was all fibreglas also, but with an HF whip at the top of the ladder and four radials on the roof (initially held down with only duct tape! -- finally changed that to using silicone seal to bond them to the roof) it worked amazingly well. I had a Hi-Q (commercially made) screwdriver antenna, but I understand the Tarheel 100HP is at least as good, maybe better.

    But 80m is a tough band, and a tough crowd who, other than the DXers hanging out in the DX window listening for weak DX, like working strong signals and if you're S7, it's easy to be ignored completely. Not strong enough!:p
     

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