Connected grounds

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N1QWI, Mar 16, 2019.

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  1. N1QWI

    N1QWI Ham Member QRZ Page

    Hi everyone,

    I have been reading the sticky posts on grounding as I prepare to assemble a counterpoise for my end fed antenna for hf. I am a little confused as to what the best way to do this is. I have attached a diagram of what I intend to do and would love any feedback as to whether or not this is appropriate?

    The antenna itself will be about 30 feet up in the sky supported by two trees. I intend to run a counterpoise down the fed and which hopefully I can run along the earth so that I can operate comfortably on the lowest bands.

    I also believe that the counterpoise should be terminated with an earth ground. In addition, the radio room in my house is on the second story, about 30 feet high. I suppose that I will have to connect the shield of the coax feedline to the house Main ground which is probably about 30 feet from the point at which the coax meets the earth after coming down from the shack and then going up to the antenna.

    I also suppose that I will have to run another wire from the second story ham shack all the way down to that main earth ground?

    This seems like an awful amount of work and lots of groundwires running around.

    Am I doing this correctly?
     

    Attached Files:

    Last edited: Mar 16, 2019
  2. WA7ARK

    WA7ARK Ham Member QRZ Page

    Is the end-fed antenna the kind that has a 1:49 transformer or a 1:9?
     
  3. N1QWI

    N1QWI Ham Member QRZ Page

    1:9
     
  4. WA7ARK

    WA7ARK Ham Member QRZ Page

    That style of end-fed does better with the transformer near the ground, connected to a ground rod near it, with the fed wire running vertical as high as possible, turning the corner and then the rest horizontal, in the form of an inverted-L. There should be more than one counterpoise; if only one, then the first radial should run parallel to the horiz wire, directly below it. The second one should run directly opposite the first radial, and so on.


    How high is the other tree? If it is higher than your 35ft support, then turn the antenna around, and make the vertical part taller.

    Isn't the "electric service ground" on one of the outside walls of your house, directly below the meter base? Is that what you diagrammed as "main ground?
     
    Last edited: Mar 16, 2019
  5. N1QWI

    N1QWI Ham Member QRZ Page

    Thanks for the info! Hopefully we are talking about the same antenna. I have an HFedz end-fed. I am pretty sure that it is a 1:9
    choke But hopefully I’m not mistaken!

    Both trees are approximately the same height. My intention is to use a drone to get the wire as high as possible!

    Regarding the “main ground quote, yes, this is the electric service ground
     
  6. WA7ARK

    WA7ARK Ham Member QRZ Page

    Is it this one?

    [​IMG]


    If so, the instructions say:
    For sale here is an end fed antenna designed for 6m-80m. Easy and fast installation. No counterpoise or ground required. Antenna can be installed: horizontal, vertical, inverted L or sloper. Almost any internal tuner can easily tune this great antenna from 6m-80m. For full coverage an external antenna tuner maybe required. Includes simple to follow installation instructions.

    53' (16.2m) #18 wire included. Build from a 9:1 UNUN matching unit. Silver plated teflon insulated wire used for core winding. Power handling 100w. All stainless steel hardware used. Counterpoise wire connection (not required but improve antenna performance). Flame retardant ABS enclosure. Great for HOA enviroments, camping, field days, activations, emergencies or where situation require easy and fast communications. Velcro strap for easy cable storage. Eye bolt added for easy hang. Antenna includes one carabiner snap hook.



    [/QUOTE]Both trees are approximately the same height. My intention is to use a drone to get the wire as high as possible![/QUOTE]

    I simulated the following four cases:

    1. The transformer is at ground level, no local ground rod, no radial(s), just coax laying on the earth for 100ft. Wire goes up 35ft, and then turns horizontal toward other tree.

    2. The transformer is at ground level, ground rod under it, no radial(s), just coax laying on the earth for 100ft. Wire goes up 35ft, and then turns horizontal toward other tree.

    3. The transformer is at 35ft agl, coax comes down to ground level and is connected to a ground rod, then runs 100 ft toward house. Wire runs horizontal toward other tree.

    4. The transformer is at 35ft agl, coax comes down to ground level and turns corner toward house. No local ground rod. Wire runs horizontal toward other tree.

    I used the optimizer in AutoEz to find the length of the driven wire that simultaneously produces the lowest SWR (at the shack end) with 150ft of 50 Ohm foam coax cable (VF=0.814, like RG8X) at the following list of frequencies: 3.8, 7.15, 14.2, 18.15, 21.25, and 28.6MHz. The starting lengths for the optimization were taken from here.

    The best configuration is case 1 with a driven wire 88.2 ft long (35ft up, 53.2ft horizontal). You would have to extend the 53ft wire that comes with the antenna. The second best configuration is case 3 with wire length = 49.4 ft, so cut the 53ft wire a bit shorter.

    So I would run the coax along the ground (or along a fence) as directly as you can toward the house, and then up the side of the house to ham shack. Drive a ground rod at this bend outside the house. Cut the coax and install PL259s. Use a SO239 bulkhead fitting and bond it to that ground rod. Run a #6 wire from that new ground rod to the one under the electric service entry panel. If that lateral ground wire is quite short, then just locate and bond the bulkhead fitting close to the electrical service ground rod and dispense with the new ground rod.
     
    Last edited: Mar 16, 2019
  7. N1QWI

    N1QWI Ham Member QRZ Page

    Here is the instruction manual: it’s an antenna for 160-6 m. Similar to the one you quoted. Will read your advice and reply separately!
     

    Attached Files:

  8. N1QWI

    N1QWI Ham Member QRZ Page

    Thanks Mike for the great advice - As you will see from the file above, it's the 160-6 meter version which actually does have a wire element of 88'. This means that your calculations were spot on!
    I wonder how this changes the configuration of the inverted L (assuming that this is still the best shape to use)

    I also note something strange in the manual above - The paragraph at the bottom (and the guy who invented the antenna) both told me that the counterpoise should attach directly from the matchbox's eye bolt, yet the schematic has the counterpoise coming from the tuner. Must be a misprint.

    OK for the grounding - I'm not experienced in bonding and honestly don't know where the service ground rod is (although I have a rough idea, since I know where the master panel is, of course). Might need to find someone to help me with that stuff.

    Appreciate the help,
    Daniel
     
  9. N1QWI

    N1QWI Ham Member QRZ Page

    I just got some advice from the antenna designer:

    He recommends a lighting arrestor in combination with a ground rod and/or radial system.

    He then goes on to state that “a 1/4 wave length radial for each desired band will be ok... if possible more than one for each band will be great but one will do the work.

    The eye bolt ground connection is more for simple ground wire or counterpoise.”

    I suppose the lightening arrestor takes the place of connecting the ground rod to the service ground, although I know it’s not up to code.
     

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