9:1 End Fed Antenna has Interesting Results on HF

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by W9MMM, Jul 17, 2019.

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  1. W9MMM

    W9MMM Ham Member QRZ Page

    Hi All,

    I dont really have a local elmher so I'd thought maybe someone could explain what I'm seeing with my antenna setup. My rig is a Yaesu Ft-991A into an LDG AT300ProII antenna tuner. I have two antennas setup, a Comet GP6 for UHF/VHF of which I've been getting amazing results mounted over my roof at around 40-45ft or so. The second antenna is for HF and is a 9:1 Balun Designs Unun which is also mounted on the roof onto the side of my home and the wire antenna is 12GA THHN solid copper wire very close to 124.5ft long that has an insulated jacket. It's being fed with LMR400 at a length of around 30ft. The wire antenna that is connected to the balun goes directly north of our house and is on a nice upward slope to a tree about 50ft out. I didnt get the wire as high as I wanted and it was in contact with some branches before going high up in the tree more in the inner part of the tree. Soon I'll be working to redo this and have the wire go directly over the top of the tree.

    Here's my interesting results: It took me a long time to get my first contact on HF with the setup and I believe a lot of it is due to the band conditions. Last week I made my first contact on 40m and was received as a 59. I've consistently had low SWR on everything below 80m. For the most part 10m and 40m dont even need to be tuned to lower the swr. This morning I has a big surprise. I tuned 80m with an swr around 1.3-1.5 and made a couple contacts. This was the first time in around a month of trying that I was able to tune 80m. I didnt change anything with my setup. The only difference I can think of is we had a heavy rain and the ground and wire was wet. We were joking around on 70cm conversation this morning that I may have to setup a sprinkler by my antenna to tune 80m. What is causing this to happen? Seems very strange to me.

    A second question out there is with the above HF setup I every so often tune like 10m or 17m and the waterfall is black and i hear very faint static but it sounds like there is no noise on the bands. It tunes to a low swr close to 1:1 but it seems very strange because there is nothing on the waterfall (black) and sometimes might see a blip above the line but nothing below. Did I mess something up here? I never hear a contact when it tunes to the black waterfall and the sound of faint static. I didnt see anything weird on my settings but I might be missing something. I wonder if I set to the wrong mode or something else weird is going on. I'll need to pay close attention to all my settings to see what it is. Anyone have any idea?

    Thanks 73,
  2. W5DXP

    W5DXP Ham Member QRZ Page

    As you go up in frequency, the band noise decreases. If you want to see/hear more noise on 10m and 17m, turn on your preamp.
  3. W5LZ

    W5LZ Ham Member QRZ Page

    I didn't see, or you didn't say anything about your ground system, either station or antenna. I wonder what that's like, because it sounds like it's being affected by the rain. Rain on the antenna it's self can make a difference, but nothing like it does if the ground system gets wet (or drowned). Any unbalanced antenna is going to be affected by grounding, doesn't matter if it's a 'direct' ground or indirect.
    I think 'DXP' pretty well answered the water-fall thingy. They are nice things to have, can give you a broad look at a band so you can see what's happening. Not with your radio, but I've used such a thing a good while ago. The 'fuzz' or small spikes are typically noise. If you don't see any, or better stated, if I didn't see any I checked to see if the antenna was still in the air (or I forgot to connect to it). That's on the lower HF bands. As you go higher in frequency that 'fuzz' tends to disappear, or at least gets smaller. Where I live there's always a lot of noise/fuzz, so I guess that's normal for here, YMMV. Ought'a really make it easier to see who'z there... (check the antenna though).
  4. W9MMM

    W9MMM Ham Member QRZ Page

    I have everything I need to ground my coax and all my shack grounds but I have not yet been able to complete it yet due to available time. It is a priority to me but I've not been able to find the time yet to do it. Hopefully this weekend i will. So for right now nothing is grounded. My antenna balun is not grounded but goes into a 1:1 unun inside the shack. Instructions said it didnt need to be grounded but I could always experiment.
    Last edited: Jul 17, 2019
  5. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Your experience has nothing to do with grounding your coax, ground rods, etc.

    Soil conditions very much influence antenna performance. Yes the moisture in the soil affects the SWR on an antenna. You will often see posts about how much better antennas perform at the seashore or aboard boats. That is because salt water is greatly more conductive than typical soil and provide a better reflective surface for forming the RF field.

    You could improve your antenna performance by covering your yard in copper or aluminum sheet underneath the antenna! :) Mesh wire fencing is a less expensive alternative. Some hams have experimented with laying multiple wires under NVIS antennas. All this metal serves to shield the antenna RF from the lossy soil which absorbs the RF, turning it into heat.

    Re. quiet band, no waterfall, there are two points here.
    -From time to time you will notice very quiet conditions on any given band. For the higher bands this happens when the MUF, Maximum Usable Frequency is very low. There is little ionization of the F1 and F2 layers and the signals are going into space without being reflected/refracted. This is common in these low sunspot days.

    On the lower bands this happens when either/or there is low geomagnetic activity (decreasing noise) or when there are solar ejections that cause the D layer ionize and absorb RF waves, and when solar activity is low.

    Waterfall: If there is little background noise on the band, then your waterfall will have less to display. Additionally, your display is controlled by the sensitivity of its settings. Most radios I have seen do not yet have AGC settings for the waterfall display. My IC-7600 is not configured well to easily adjust the waterfall gain. The computer based SDR radios/displays seem to have more functionality in this area. So... if your waterfall goes blank (and mine does at times on quiet band conditions) try 1. Turn on RF Preamp, if equipped, 2. Adjust the waterfall sensitivity settings.

    K0UO and NH7RO like this.
  6. W9MMM

    W9MMM Ham Member QRZ Page

    Well I'd like to keep the conditions I have under the wet environment. Is there something I can do without doing it to the grounds around the antenna? I cannot put things on the ground. We have horseback riding going on and other things going on around there.
  7. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    -Irrigate your lawn.
    -Apply conductive salts like Sodium Chloride (rock salt) or Magnesium Sulfate (Epsom salt) which may kill grass and plants.

    -Alternatively, elevate your antenna. The further from soil, the less effect is has on the antenna.
    NH7RO likes this.
  8. WA7ARK

    WA7ARK Ham Member QRZ Page

    K0UO likes this.
  9. W4OKW

    W4OKW Ham Member QRZ Page

    The face looked familiar, but didn't recognize the call! 73 from Pax River de Tom W4OKW
    KA0HCP likes this.
  10. KI8DJ

    KI8DJ Ham Member QRZ Page

    Try cutting a foot at a time off the antenna to get 80 to tune you need to find the sweet spot. I have the same Unun with about 75 feet of wire and it tunes 80 through 6 on my rigs internal tuner,as well as the upper half of 160.

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