hardware for attaching a wire antenna to a house

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KE0YRP, Dec 14, 2019.

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  1. N7WR

    N7WR Subscriber QRZ Page

    What frequency bands are you intending to use the antenna on and do you have an antenna tuner. Is the "counterpoise grounded? More info needed
     
  2. K1LKP

    K1LKP Premium Subscriber QRZ Page

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    KE0YRP likes this.
  3. KE0YRP

    KE0YRP Ham Member QRZ Page

    idk yet. 40 and up of course. they claim it doesn't require a tuner, but I saw a vid where the guy was having some issues with it. I'll buy a remote autotuner if needed.

    My plan is 7300 --> 25ft of LMR-400 --> lightning arrestor --> MFJ EFHW. hang a single counterpoise... enough to drape on the ground a bit. need to read up on the lightning protection. I bought a 8ft ground rod and #6 copper wire and some connectors, but idk if I'm going to be able to put the rod in the ground. there are buried wires, etc. in the area. obviously, i'll call one call before having anything done. lots of stuff to hit. 20191208_142020 draw.jpg
     
  4. KE0YRP

    KE0YRP Ham Member QRZ Page

    I have to be as unobtrusive as possible... I'm in a HOA where antennas aren't allowed. :(
     
  5. N7WR

    N7WR Subscriber QRZ Page

    There is most likely a ground rod at the service entrance to the left of the gas meter. You can tie into that without having to drive another ground rod. I "assume" the feed point is close to where the red and blue lines come together. If you are running barefoot from the IC 7300 the tuner in the radio should suffice. Doubtful an external auto tuner will handle a greater mis match than the internal tuner.
     
    NH7RO and WB5YUZ like this.
  6. KE0YRP

    KE0YRP Ham Member QRZ Page

    you are correct on the location of the feed point. I'll try to figure out if there is an existing ground rod.. thank you!

    What do you mean by barefoot?

    Stupid question, can I use insulated wire for the lightning ground? it would hide better than bare copper.
     
  7. N7WR

    N7WR Subscriber QRZ Page

    Barefoot means running the 7300 without an external linear amplifier--so 100 watts from the 7300. There must be a ground rod at that service entrance. As for the ground wire I would recommend heavy gauge stranded copper wire (I use #2) for my grounds. You can spray paint it whatever color you want to hide it
     
    KE0YRP likes this.
  8. KE0YRP

    KE0YRP Ham Member QRZ Page

    okay yes, no external amplifier.
     
  9. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    Keep the counterpoise a little elevated and in the clear. The counterpoise will have high voltages on the end of it. If you have the end or anything near the end draping on the ground the effectiveness of the counterpoise will be greatly lowered and you will have lots of ground losses.

    Obviously, you will also want to keep the counterpoise, especially the end or the part near the end, away from the gas meter and associated metal plumbing! (Boom!) You will have to try and place it so people and animals cannot come into accidental contact with it.

    I personally would standoff insulators to mount the antenna to the side of the house.

    You haven't said yet what mode(s) you will be using. If you are using FT 8, you may be quite happy with this set up. If you've already bought that antenna, put it up and enjoy it, and don't bother reading any further.

    If you haven't bought it yet, though, I must say that were I in your shoes, I would definitely hang a fan dipole in that same space for now, for 10 and 40m. No question.

    After you upgrade, you can add elements for 20m, bending the ends of the 20 and 40m elements if necessary into a "U" shape to fit the available space.

    The end-fed half wave has an apparent physical simplicity, which is no doubt appealing; but this belies the amount of effort sometimes needed to make it work well, especially in an environment like this.

    Here's a good example, from the instructions MFJ supplies with its end fed antennas:

    "care should be taken to route the feedline vertically away from the
    feed point as far as possible, and also to keep the feedline away from metallic
    objects. These considerations are of somewhat greater importance for an endfed
    antenna than they are for a centerfed antenna."

    I also note you plan on running 25 ft. of coax from the radio to the antenna. The instructions state:

    "The disadvantage of end feeding is that tuning is related to feedline length. The
    general rule of thumb is that feedlines that are a multiple of a quarterwavelength
    for any given frequency band may present tuning difficulties on that
    band."

    So you will need to read the instructions and choose the length of coax accordingly.

    The half-wave dipole is actually an easier antenna for most people to make work well in the long run if the antenna must be near the house and all its wiring/electronics. It will also keep the high voltages up high where no one can accidentally touch them, unlike a counterpoise installed as you describe.

    Overall, I think you would have less trouble with a conventional dipole. But again, if you've already bought the MFJ, don't worry about it, just put it up and enjoy it!
     
    Last edited: Dec 14, 2019
    NH7RO likes this.
  10. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    I waited too long to edit the previous message.

    OP needs to read the instructions for this antenna before going any further. Explanation forthcoming.

    (Later)

    Okay, there are apparently different kinds of MFJ end-fed antennas. I was thinking of the MFJ Zepp family when I posted much of the above. However, I've now learned that MFJ has come out with a family of end-fed halfwaves using a transformer and fed directly with coax, similar to myantennas. Surely this is the type of antenna OP has in mind!

    It is embarrassing not to be able to remove the comments above. However, in my defense, if OP had included the model number of the antenna in question I could have read the correct set of instructions to begin with...

    I would still prefer a conventional center-fed 10 and 40m fan dipole for my own use. But again. for FT 8, OP may be very happy with this set up.
     
    Last edited: Dec 14, 2019
    NH7RO likes this.

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