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Old 07-29-2018, 07:09 PM   #8
NN5I
Carl, nn5i
 
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Join Date: Sep 2011
Location: Tallahassee, FL
Posts: 1,441
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I am skeptical of the Ultimax. Incidentally, the web site says no radials are needed.

Some thoughts:

(1) I'd like to see what's in the box. If there are any resistors in there, at all, it's a dummy load. A decade or two ago, the ARRL Lab disassembled some commercial "miracle" antennas and found exactly that, so it wouldn't be unprecedented.

(2) In any case, the box isn't a balun, neither 4:1 nor anything else. A balun is a two-port device; one port (the unbalanced side) can be a coaxial connection like the one on this box, but the other must be a balanced connection; two binding posts, typically. This box has only a single output connection, so it isn't a balun.

(3) I can imagine only one reason to require a minimum 30 feet of coax between tuner and antenna box. That would be to dissipate power in coax losses with a sky-high SWR in the coax. Making the coax lossy makes it easier to match, because the reflected power going back down from the box to the tuner is reduced by the coax losses in two directions. In other words, it turns the coax into a dummy load.

Who knows? Maybe they've devised some great breakthrough and I'm all wet. Wanna bet?

I could design an antenna that would look like this, more or less, but it would work on only one band and the length of the external wire would be a half-wave for that band. Inside the box would be a quarter-wave coaxial matching section, shorted at one end, tapped for the input somewhere in the middle (about 14% up from the shorted end if using 50Ω coax for the feedline), and with the external wire connected to the center conductor at the other (non-shorted) end. Basically it would be a coaxial (instead of twin-lead) J-pole for a specific band. It wouldn't need a tuner, either, nor radials.
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