Constructing a 6m ¼ wave Ground Plane Antenna Question

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N6TDG, Apr 7, 2021.

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  1. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Well, it's certainly a bit more problematic due to the 500 kHz input/output spacing and the size and cost of the cavities required for the duplexer; also, the antennas are larger and heavier and may be more problematic to install.

    But there are a lot of 6m repeaters -- about six of them are line-of-sight to me so could be worked easily with a low powered handheld. However, not much activity on any of them!:p
  2. N6TDG

    N6TDG Ham Member QRZ Page

    This might be the way I go. I do have to take my bulkhead connector down to All Metals to see if they actually have any thing that will fit. K6CLS brings up the fact that aluminum is easy to machine and I have no problem with slight modification to get it to fit into the connector hole.

    8G copper wire fits nicely but then again, it is very soft and bends to easy for this build. Twisting two lengths together was suggested and that could be a way to go for strength. It is also easy to trim to SWR than stainless.

    The nice thing about using a stainless rod is that it does not bend as easy as copper.

    So it looks like a trip to All Metals and then Home Depot to see what everyone has.
  3. AK5B

    AK5B Ham Member QRZ Page

    The whole point of twisting is to make it considerably stiffer. Easy solution at hand.

    Also, likely that all you need to twist is the radiator with a 5-foot length (twisting will shorten it a little). Use regular wire sloping radials with Dacron line as guys and you'll be all set to go in no time.

    Been there, done that sort of thing.


  4. WZ7U

    WZ7U Ham Member QRZ Page

    The weight savings alone should make aluminum the choice. I'm of the opinion that tube is more rigid than wire at that size.
  5. KJ4RT

    KJ4RT Ham Member QRZ Page

    If you know anyone in construction who hangs ceiling tile, grid hanger wires would be stiff enough and probably cheap enough. This is what I am thinking of using for a 6 meter GP.
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    To stiffen the copper wire, the recommendation isn't to twist two lengths together, it's to secure one end in a vise, the other end in a drill chuck, and twist the single wire strand which will harden it while also making it slightly shorter. Actually, with "normal gauge" copper wires I use for a lot of stuff (14AWG, 12AWG), I've found several ways to "stretch" it which also hardens it very well (such as tying a length to two garage door brackets on opposite sides of my garage door and hitting the middle of it with a sledge hammer! Sounds silly but it does work.)

    However #8 wire is pretty thick and these processes may not work as well -- or it will much more difficult to make them work.

    Using SS rod or thick wire for anything I'd intentionally cut it too long and trim it with a fine triangular file to cut a notch then snap it off with pliers. It is too hard for normal wire cutters.
    That's the whole reason mobile whip antennas are all stainless steel, or SS covered by something (but still SS inside). It actually does flex very well, but snaps back to being straight when the obstacle is gone and doesn't take a permanent bend.

    BTW aluminum (tubing) was mentioned, and aluminum is great: Strong and an excellent conductor. But you can't really solder to it. It can be welded.

    An easy way to make a ground plane for any frequency band is starting with an "L" bracket made of thick aluminum or thinner galvanized steel, with holes punched (before bending) or drilled (before or after bending) to accommodate a U-bolt for fastening the antenna to a mast, then more holes for an SO-239 connector, then a hole for an insulated 3/8-24 internally threaded sleeve that will accommodate a standard 3/8-24 whip antenna, and using flexible copper wire to connect the center of the SO-239 to the 3/8-24 mount.

    Strong, allows easy mounting on a supporting mast, and will allow use of a wide variety of antennas made of stainless or whatever you wish.

    Such mounts can be purchased prefabricated and ready to use for about $20.
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I was discussing something like this above ^^

    This kind of simple bracket allows for mast mounting, and installing any kind of whip antenna with a 3/8-24 threaded stud base. Holes in the bracket accommodate up to four aluminum tubing radials which can be straight out or angled downwards.

    A 3/8-24 base "CB" SS whip antenna (see below) can be cut down to 54" long (or whatever) for 6m operation.
  8. WA4SIX

    WA4SIX Ham Member QRZ Page

    Steve, I tried this with my drill on High & 14AWG stranded wire.... Looked like my first time using a conventional fishing reel...

  9. K8JD

    K8JD Ham Member QRZ Page

    I don't want to count up all the days I ran my scanner from 52.5 to 54 MHz, for many hours, and never got a hit !
  10. N6TDG

    N6TDG Ham Member QRZ Page

    Ihaven't had time yet to research which material I will use--you know--life interruptus...

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