Jerry,
The Cushcraft MA-160V vertical happens to be 35' tall. I believe there is
a capacitance hat at 23' with an inductor of unknown value just under the
hat. The hat spokes are 48" and there are 8 of them. Above that is a
"stinger", an adjustable element that can be lengthened or shortened to bring
the system to resonance. The OD of your element is larger than that of the
MA-160V, suggesting that the size of the coil needed may be marginally
smaller to bring the system to resonance.
There is a user manual available online that details the construction of
the antenna. It is really very simple, 23.5 feet of aluminum, inductor,
hat, and adjustable aluminum "stinger" in that order. Read the eHam reviews,
they are overwhelmingly positive, especially for an antenna of this size.
You might check with some of the eHam reviewers about replicating the
design, the value of the inductor being the only unknown. I believe Cushcraft
even has the inductor listed as an individual part number. Perhaps they
would sell you one separately. If there is anything more to this design that
I might have missed, I can't determine it from the manual. Users?
Perhaps more intriguing is that you might be able to tap the inductor for
80M and short out the unneeded inductance via a control cable inside the
aluminum tubing. This design probably isn't optimized for that band, but it
may still outperform at least some of the alternatives.
I'm somewhat familiar with the design because I have a tree branch at 35'
that would support a wire version of this design and is inside a cluster of
trees that would hide the entire antenna, a must in my covenant-restricted
neighborhood.
YMMV, but it is a proven design that should be easy to replicate. I don't
encourage pirating of commercial designs, but emulating this for
comparison against other designs is well within the spirit of ham radio antenna
design IMHO. Good luck!
73, Paul, K5AF
In a message dated 10/25/2011 12:14:52 A.M. Central Daylight Time,
k3bz@verizon.net writes:
I have an aluminum tubing vertical that I no longer need to use on 40M.
Bottom 18’ is 3” OD; rest is 1” OD, length is adjustable to max 35’. I’m
looking for details of a good way to use this as part of a vertical for 160M
(and/or 80M) that might be better than an inverted el. Ideas?
73, Jerry K3BZ
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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