My situation: 66' end fed vs ZS6BKW

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KG9LD, Apr 16, 2021.

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  1. K1LH

    K1LH XML Subscriber QRZ Page

    The ZS6BKW not bad, I had one up for a while. The Window line should be kept away from other metal objects, and putting a few twists can also help prevent it coupling with things based on what others have said - thou someone may have actual data on that/my terminology may be off - I've not worked with the stuff much. A good 1:1 current choke should be used where the coax meets the balanced line.

    I recently converted my ZS6BKW into a 40ft elevated (base is 10ft above ground) vertical doublet using a 40ft Spiderbeam fiberglass pole, with the 450 ohm line leading away at 45 degree angle to an AH-4 tuner, one side to ant terminal, other to gnd lug (gnd lug not connected or grounded to anything else), the coax and control cables have chokes which float the tuner above ground. This works fairly well from 40 to 10m. It's not too far behind my 80m OCFD at 55ft in performance. Find the blogger link on my QRZ page (couple posts down from the top now) for more about it.

    Having said that, if you can get a horizontal antenna around 1/2 wavelength high on its lowest frequency or at least on 20m it'll outperform a vertical in most cases. Exception being 80m for NVIS where having it under 1/2 wave length high is better for example.

    If you can I'd run the coax along the ground where possible, the dirt acts as a lossy media and helps prevent currents/noise traveling on the outside of the coax. All my coaxes follow the foundation of the house just below the surface to where the shields are grounded and enter the house (get the ARRL grounding and bonding book to know how to do grounding right).

    WA7ARK's advice is good info too.
     
    Last edited: Apr 16, 2021
  2. 2E0VSS

    2E0VSS Ham Member QRZ Page

    Andrew Roos
    He's a ZS call and very very smart.
    He has an ingenious dual band 40/20 metre dipole published.
    He used to be ZS1AN but has changed his call now, he is still active for sure.
    You may have to do some digging for the article.

    M
    73
     
  3. K6GBW

    K6GBW Ham Member QRZ Page

    If you have a 66' wire with a transformer then it is likely a 49:1 transformer making your antenna an end fed half wave. If you have a high SWR on 20 it is probably due to the way it is mounted. You can try moving the coax into a different position and it might make a difference since that particular antenna uses the coax shield as the second half of the antenna. All that said, the ZS6BKW will likely be a better performer. I have one that I built from scratch and it is much better than my EFHW ever was. Jut make sure you feed it with good coax for best results and use a good tuner. Mine is fed with about twelve feet of LMR400 right into the window line. No balun used and with a manual tuner I easily tune 80-10 meters no problem. The antenna is at only thirty feet and out performs my previous EFHW by a wide margin. You might try running the window line under the eave of your house. I mounted 1.5" PVC pipe under my eaves and ran the window line through it and it works great. The window line passes by my roof flashing by about 2 inches and it doesn't cause any problems. Both antennas are good. I just think the ZS6BKW is better. Good luck!
     
  4. 2E0VSS

    2E0VSS Ham Member QRZ Page

    You should use a 1:1 balun on the ZS6BKW at the Junction of the Tuned feeder to coax.
    There is NEVER ever any excuse NOT TO. Correct engineering practice dictates this.
    See the web page of IZ2UUF and you will see the practical experiment he takes you through.
    M
    73.
     
  5. K6GBW

    K6GBW Ham Member QRZ Page

    VSS, maybe so. But I've been busy and haven't gotten around to it yet. In the mean time, my little tuner trims it flat and I can operate. Maybe one day I'll install one.
     
  6. N4UFO

    N4UFO Ham Member QRZ Page

  7. K8JD

    K8JD Ham Member QRZ Page

    Another Solution
    I have had pretty good results with a 20 M EDZ (dipole wire element is bit over 90 Ft end-to-end) using 450 Ohm twinlead right into the shack with a MFJ974 balanced line tuner.
    It also can be used with good results from 60-17M operation.
    There is no BalUn or special feedline length to worry about. In my case, Feedline of 150 ft should have very little losses.
    I used some old plastic items fastened on the roof to keep the line from laying on the roof shingles. Getting wet or snow/ice sticking to the feedline does cause some changes in tuner settings.
    If you make your own antennas, the cost of wire and coax/twinlead is all you have and you can try different antennas and makeup your own mind.
     
    Last edited: Apr 18, 2021
  8. K8JD

    K8JD Ham Member QRZ Page

    WN1MB likes this.
  9. WA7ARK

    WA7ARK Ham Member QRZ Page

    The suggestion was to the OP. You notice that I did not tell him to buy one. I told him that after he is done, it should look like/work like the linked commercial products. I then offered to help him build one...
     
    Last edited: Apr 18, 2021
  10. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    Let's be clear on this one: probably not very well. It's a good idea to avoid that configuration entirely.
     

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