George, I can't say one way or the other, could be the antenna in
question or something similar. I never personally touched one but saw
plenty of them atop tuna boat masts and crow's nests as well as some at
residences. It seems to me to be an easy way to get on the air with
something with some directivity and "aimability", at least with useful
steerable nulls. I like solutions sans traps when available.
Patrick NJ5G
On 4/28/2016 7:52 AM, George Dubovsky wrote:
Patrick,
Back in the day, a company called Kirk made a series of what they called
"helicoidal" beams. The elements were tapered fiberglass with approx 1/4"
wide, thin copper strap wrapped around in a spiral, and the whole thing was
covered with something like spar varnish. Ring any bells?
73,
geo - n4ua
On Thu, Apr 28, 2016 at 8:44 AM, Patrick Greenlee <patrick_g@windstream.net>
wrote:
Once upon a time a long time ago in San Diego many members of the tuna
fleet were equipped with 4 band HF antennas called cat's whiskers (due to
appearance.) They were 4 sets of horizontal dipoles driven with a single
coax feed to a common midpoint. The dipoles came close together at their
midpoint(s) but were "splayed" out several degrees so that farther out from
the center point they were farther and farther apart in 3 dimensions, not
2. The elements were copper wire wrapped helical fashion on stout
fiberglass poles. The wire was secured by a top coat of resin. I'm not
sure if it was epoxy or polyester resin but it was UV resistant and lasted
well in the harsh marine environment.
There was, of course, some interaction between bands when trimming to tune
for initial setup. Most installations did not use antenna tuners but some
skippers and some navigators were hams and some of these used tuners to
broadband the antennas for ham as well as marine HF bands.
This sort of antenna is fairly easy to DIY. Being balanced
aerodynamically they put a light torque load on the rotor/rotator due to
wind. They are relatively light weight and don't require a super HD
rotor/rotator.
Some of the users in the tuna fleet did not employ a rotor/rotator and
instead turned the boat to aim the antenna, an option of which many
residences can't avail themselves. There were some cat's whiskers
installed at residences of hams in the family of tuna fishing hams and
seemed to work satisfactorily. I regret not being able to quote chapter
and verse as to source, mfg, etc but this was some decades back so I'm
claiming "Senior Privileged" employing selective memory.
Patrick NJ5G
On 4/28/2016 6:46 AM, kr2q@optimum.net wrote:
I googled your QTH and the QST article antenna probably won't work in
your situation since your
roof tower is way too short and the "dangling wires" will hit your house.
Since you are a real ham (IE, cost is a factor), check this out and maybe
you can get some ideas for
a modified approach for a shorter version.
http://www.pa1m.nl/pa1m/a-shortened-40-meter-rotary-dipole/
GL
de Doug KR2Q
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