My Force 12 Mag 620, a 6-element 20-meter beam, quit working recently. I
don't know if it was due to some lightning storms or not, but when I
reconnected the coax back to the transceiver after the storms, it showed
very high SWR and the Alpha went red on the front panel.
I used my MFJ analyzer to note the lack of dips in the frequency scan and
high SWR on 20 meters. After
moving the analyzer outside to the base of the tower, I had no change in
readings. Yesterday, I climbed the 90' Rohn 45 tower and removed the
feedline
coax's PL-259 coming up through the tower to a DX Engineering bracket
holding two barrel connectors (to interconnect to antenna pigtails). MFJ
testing at that point showed no change to the problem. The balun is about 8
feet out there in space, but I could not see anything wrong from the top of
the tower. That is the only thing left to blame.
The balun I was using was the original Force 12 bought around the year 2000
before they moved to Texas. The 5KW balun is in a small black-colored
epoxied case (3" x 3" x 1.5")with a PL-259 on one end and two wires coming
out of the other end to connect to the two isolated driven elements. I
checked the archives for comments on Force 12 baluns and found a few
comments though.
Has anyone had bad luck with these older style of Force 12-supplied baluns?
One other thing, I can receive with the antenna, and when I turn it with the
rotator, it peaks and dips on any station just the way a directional antenna
does. There is really nothing left except the balun or the connections
there. Right?
Without asking everyone about their "favorite" brand of balun, I would like
to hear from anyone who has used a different modern balun successfully on a
typical Force 12 antenna like my Mag 620. I am really interested in how you
fastened it to the boom.
Steve Sala
K7AWB
DN17es
Nine Mile Falls, WA
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