Building a ZS6BKW

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N6UM, May 31, 2021.

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  1. W2AAT

    W2AAT XML Subscriber QRZ Page

    The W5GI is similar to the ZS6BKW. I trimmed my 450 ohm ladder line to give me the best possible SWR on 40m. It works great on 40. On 20 and the other bands I use my trusty Heath SA-2060. As others have posted, trim for the band of your choice and antenna tune the others. Do this, and you will be happy:)

    One other thing... Write down the length of your ladder line so that if you have to replace it, you won't have to play games when it comes to replacement.
  2. AB6RF

    AB6RF Premium Subscriber QRZ Page

    I think it's by far easiest to snip little bit off from the bottom end of the window line.
    Use some kind of screw terminals for the balun, and it becomes trivial to disconnect the window line and cut off an inch or two.

    You can even use these "Euro style" terminal blocks to make the connections during the trimming process, and then change to something more permanent once the trimming is done.
    (or just leave the terminal blocks in place, I've done that it worked fine until I went back and soldered the wires over a year later)

  3. K7JOE

    K7JOE Subscriber QRZ Page

    Question: the ZS6 ladder line is 39 or 40 ft long. Your antenna is up 35 ft. What are you doing with the extra ladder line? That might be why you're not getting a proper tune. If your elements are 46ft each and your ladder line is 39 ft, you should be in good shape on 20M and 40M with pronounced dips (below 1.5:1) at some point on both bands.

    For me: I'm lazy so always try to just trim ladder line. I cut the ladder line about 5 feet up from the balun and trim out a section from there.
    I do this because it is easy to do. Once a chunk is removed, strip the ends of each piece of ladder line, make a U-shaped bend in each wire on the ladder lines and use gravity to "hang" the balun onto the shortened ladder line using those interlaced U's. Soldering is a one-person / one handed operation.

    That point where the ladder line was cut now provides a convenient spot to add a capacitor across the ladder line to "add a band" like we do to tweak the 10M portion into resonance per W5DXP web site. Modifications.pdf

    To seal the ladder line up I use the tacky coax seal stuff or liquid electrical tape. I don't mess with regular electrical tape as it will come off in no time. It should be sealed bc most ladder line is made from copper coated steel copperweld solid wire and will rust and break after 5 or 10 years if not sealed from moisture.

    Dont mess with any connectors or screw terminals or crimp barrels's asking for trouble as they become intermittent. Cut, bend into a U, and ever time. never had one come loose either.
    Last edited: Jun 9, 2021
  4. 2E0VSS

    2E0VSS Ham Member QRZ Page

    You certainly won’t get a decent marriage with 300 ohm window line.
    I’ve had three attempts with 300 ohm and I could never get 40 and 20 to marry up.
    This antenna returns better VSWR figures when using 400 to 450 ohm feeder.
    Exactly as Mr Austin anticipated..
    If, however you opt for the G5 with hybrid feed, the situation is reversed and 300 ohm returns preferable figures.
  5. KK6WBS

    KK6WBS Ham Member QRZ Page

    Thanks for the reply! I have the extra ladder line lifted about 5 feet sitting on top of the fence. Then 100 Ft of LMR-400 going into the shack. Any other ideas for the ladder line ? Interesting re: 10M modification. Does the mod mess up any of the other bands ? Does it work effectively on 10m, have you tried it ? 73
  6. W2AAT

    W2AAT XML Subscriber QRZ Page

    The vertical drop is very important. You might be able to loop the end into a coil. There are several here on the antenna forum that can work magic with the modeling program(s). They may be able to give you the dimensions of the loop/coil and how it would affect your swr and radiation pattern.
  7. K7JOE

    K7JOE Subscriber QRZ Page

    The ladder line should not lie on itself nor should be too tightly spaced... ... a corkscrew method through a rope, or hanging the ladder line in a horizontal "wave" along the fence is usually sufficient. Don't hang it on metal nails ... use some rope to hang it.

    The 10M mod does not effect other bands. Read the paper that I posted and it explains all the details. Yes, it works but of course every antenna installation is different. You could also use a small variable capacitor across the ladder line 5 ft from the end and "tune" in the 10M band... lots of mods.

    Get out there and experiment.

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