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Thread: Tower balun

  1. #1

    Default Tower balun

    I rearranged my room (with the computer cables and speaker wires along the wall with the tower (a foot away). Now, when I key up, there is absolute chaos in the room. Computer goes haywire, i come through the speakers etc...

    I know, common-mode current... or so I thought. My clamp-on RF probe shows very little power coming down the coax (I have no balun but assume the lack of signal on the shield is because that path is very near a multiple of half wavelengths and thus presents a high impedance at the beginning of the shield) so I have came to the conclusion that the tower itself is radiating. After hours of reading online, I stumbled on a website explaining that, when people model ground plane antennas, they rarely take into consideration the tower being connected to the same thing the radials are and therefore the tower acts like a ground radial just the same.

    This raises the question: Has anyone had luck adding a 1/4 wave conductor in proximity to the top of the tower and connecting it to the tower 1/4 down? In other words, can I bazooka-balun my tower? The tower legs are interconnected and im sure the unique geometry would lead to much trial and error but im curious what opinions are out there on the subject.

    edit. maybe orient that bazooka element in the center of the 3 legs???

    edit2: and now im thinking about a caged-wire element running up the center of the tower and also have the coax running up through the middle of the wires. So on the top of the tower (where my GP antenna is mounted right on a leg) have a 2x6 pine board zip tied to the top tower cross support rods and in the middle of the board have one hole in the center for the feed line (which makes no physical connection to the bazooka) and 4 evenly spaced (in a circle) holes to support the 1/4 wave caged wires that are soldered together at the top. A quarter wave down do the same thing with the board but make those 4 ends join up to the tower supports. It would therefore resemble a bazooka for the tower AND coax...
    Last edited by brandon lind; Wed 20th May 2020 at 22:30.

  2. #2

    Default

    Update: That worked. If the path from the feed point down the coax and down the tower are nearly equal, the signals on each should have nearly the same phase at any given distance down the tower. This allowed the bazooka to be fed from the tower instead of cutting through the coax jacket to achieve a connection. Who wants to let water in their coax? Nobody. This worked awesome. Horrible RF in the house to absolutely nothing!

    I make a quick video so people can see what I did.
    https://youtu.be/6P-xTBlqtTA

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