Using a MFJ1786 mobile...

Discussion in 'Mobile Radio' started by KI4ZJI, Jan 2, 2015.

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  1. KI4ZJI

    KI4ZJI Ham Member QRZ Page

    What are your thoughts on mounting the MFJ1786 on a bumper-mounted mast so that it is above the rear of an SUV (Ford Explorer) for mobile operation. I understand there will be nulls in the donut hole, but that's okay.

    1) Will it work
    2) Will transmitting (100w pep ssb) fry the electronics in my car (and my brain).

  2. KO6WB

    KO6WB Premium Subscriber QRZ Page

    1. Yes
    2. Probably on your brains but less likely on the electronics.

    The 1786 is kind of flimsy in the construction surrounding the tuning capacitor and the coupling loop. It may not survive sustained wind loads on the thin plastic covering.
    You'd probably want to re-enforce that part of the assemble. Also your mount for such an installation would need to be very health, especially if the loop is not inline with the vehicle.

    Other then the looks folks will give you, it work fine.

    Have fun
  3. KI4ZJI

    KI4ZJI Ham Member QRZ Page

    Thanks, Gary.

    My biggest concern is being able to communicate with the QTU. Depending on the day, I work anywhere from 60 - 120 miles from home. I am looking for a bullet-proof way to talk to the house if the feces hits the fan. So, generally, being pointed up (NVIS) or generally in my direction of travel (to or away from the QTH) will be perfect.

    I know most people use screwdrivers for HF mobile, but I would think that a pure vertical would not work well for NVIS. Please correct me if I am wrong, but at that distance, ground-wave would skip right over the QTH.

    I've also thought about a long whip on the front bumper, run through a remote tuner such as an Icom AH=4. Perhaps bending the whip back over the vehicle would work for NVIS?

  4. KO6WB

    KO6WB Premium Subscriber QRZ Page

    There is no NVIS on the bands the MFJ-1786 covers. There may be a small amount on 30 meters but that would be doubtful.
    NVIS occurs on the lower bands like 80, 60 and 40 meters. The best ground wave is on 160 meters.
    The efficiency of a mobile antenna isn't very good on these bands but loads of mobile operators make contacts everyday.
    A screwdriver antenna works well, depending on the installation, on 40 meters and up.
    For 60-120 miles during the day 40 meters works well. There will be dead spots along the way so it's not 100%.

    Hope this helps
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