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hanging a vertical 2m antenna

Discussion in 'General Technical Questions and Answers' started by W4EAE, Dec 4, 2018.

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  1. W4EAE

    W4EAE Ham Member QRZ Page

    I will start with my limitation. At my QHT, the only way that I can get a 2m antenna high in the air is by hanging it from a ~100ft pine about 30 feet from the house. At the moment, I have a 'slim jim' modified J-Pole made from 1/2" copper pipe suspended from the tree. The top of the slim jim is exactly 72 feet in the center of the state of South Carolina. The antenna is fed with LMR400 which is connected to a Yaesu FT-2980 80w 2m radio.

    This configuration gives me the following:

    repeaters within 35 miles in all directions
    simplex users with similar height advantages to mine within 25 miles
    repeaters within 85 miles are reliable from north-northeast to west-northwest
    the change in temperature the first couple of hours after sunrise brings me repeaters up to 130 miles NNE to WNW reliably
    My record DX contact during inversion is 258 miles (I've only been doing this a couple of months)

    My goal is to increase my reliable range, making me less dependent on weather (inversions).

    Height cannot practically be increased; the limbs at the top are just too small and close to the trunk. I posed all of this to some local amateurs who advised me that a higher gain antenna might do the trick. The two antennas with the highest gain that I can find are the Comet GP-9 and the Diamond X510HD. I have ruled out directional antennas as the antenna must be hung, not mounted.

    Would it be possible to hang either of these antennas, or must they be mounted from the base? Also, since both of these antennas are 17 feet tall, the enter of both antennas would be about 8 feet lower than my current antenna

    In addition, any feedback about whether or not this will help me achieve my stated goal or not would be appreciated.

     
  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    That should provide more gain and more coverage, but I'd use a single-band 2m only gain vertical instead of the GP-9 or X510HD, which are both dual-band antennas and more prone to possible breakage.

    These antennas use couplers to join sections (electrically, inside -- and mechanically, outside) and all the weight is near the bottom where the aluminum tube for mounting and radials attach, so "dangling" it from a tree limb above might strain the couplings and create a failure mechanism over time.

    The Diamond F23H is gain equivalent to the X510HD but is a single-band, 2m only antenna that is likely more reliable as it uses fewer internal connections.

    Remember all these do use rigid radials at the bottom, which are required; will they slam into the tree trunk or cause some other mechanical problem?
     
  3. K8JD

    K8JD Ham Member QRZ Page

    Hanging, with a good insulated attachment, would work fine.
     
  4. K3XR

    K3XR Ham Member QRZ Page

    Have several verticals in trees at this location. Start with 1 1/2 to 2 inch PVC pipe attach a "T" connection to the top and bottom of a section (10 ft.) of the pipe. Get a good quality 1/4 inch rope over the tree limb of interest attach the bottom of the rope to one "T" and the top of the rope to the other (top). Take stainless steel hose clamps lay the vertical alongside the PVC and secure. Raise the entire setup similar to a flag and secure the rope. Some have been up in the trees around 20 years.
     
  5. W4EAE

    W4EAE Ham Member QRZ Page

    As to the specific choice of antenna, I selected the X510HD over the F23H because it has higher theoretical gain at 3 5/8ths wave as opposed to 2. Should I expect better performance from the F23H despite its lower gain, or does the theoretical gain not really hold up in reality? (this is legitimately a question, not sarcasm :))

    As to the radials, I have taken them into account. I actually have already thrown the lines. I have a pathway up that I can work the radials through; and once it is up, they should be clear by several feet on either side. I also plan to use a near-horizontal line a few feet below the antenna, attached to the coax. This would function both to stabilize the antenna, and to support the coax.
     
  6. W4EAE

    W4EAE Ham Member QRZ Page

    Is the antenna secured directly the PVC for 10 feet of its length, or is it set out from the PVC and secured to the Ts at the top and bottom of the PVC?
     
  7. K3XR

    K3XR Ham Member QRZ Page


    Secured directly.
     
  8. KV4JW

    KV4JW Ham Member QRZ Page

    Well, you obviously can't get any higher. You're using excellent coax as well for VHF. To maximize range, with the same power output, you're going to need gain. If a directional antenna isn't possible (and it isn't given circumstances), I'd be looking for the absolute highest gain omni two meter antenna available.

    Tram 1481 is supposedly a whopping 8.3dB gain, but costs about $80 and is rather long.
     
  9. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    The F23H is also 3 x 5/8-wave (see below). Having used both models many times, I'd greatly prefer the F23H for "2 meters only" operation -- there's less stuff to go wrong, inside.

    F23H.PNG
     
  10. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    The Tram would never hold up for this kind of installation.
     
    KV4JW and K3XR like this.

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