Hmm, the link didn't take! The info is on QRZ.com/VE6WZ
73, Stew K3ND
From: GALE STEWARD via Topband <topband@contesting.com>
To: "topband@contesting.com" <topband@contesting.com>
Sent: Tuesday, October 11, 2016 11:59 AM
Subject: Re: Topband: 80m rotatable dipole load coil questions
Here's a link to a 80M yagi designed and built by VE6WZ.
Some good loading coil info.
73, Stew K3ND
80m 2-el Yagi
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80m 2-el Yagi
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From: Grant Saviers <grants2@pacbell.net>
To: Ray Benny <rayn6vr@cableone.net>; "topband@contesting.com"
<topband@contesting.com>
Sent: Tuesday, October 11, 2016 11:35 AM
Subject: Re: Topband: 80m rotatable dipole load coil questions
From a coil loaded 80m 2L yagi (bought JKantennas) and 80m rotatable
dipole I built and reading here are some thoughts.
My rotatable 80m Tornado loaded 86' dipole at 100' doesn't have much of
a pattern, height is everything and at about 130' or so they really
start to play. The beam is at 157'.
Element gap isn't too important - wide enough to stand the voltage,
strong, and UV durable. 2" is ok. A fiberglass solid rod with paint
would work, or a UV resistant plastic sleeve over the FG. No steel or
SS near the coil if possible.
IMO, there is very little loss difference with 1/4" tubing Cu vs Al.
Good electrical joints are probably more important. Coil L/D ratio
about 1 and turns spaced tubing diameter seems to be about optimal for
highest Q. Any form will reduce Q, so best to avoid them and make the
coil self supporting. I use
http://hamwaves.com/antennas/inductance.html for a coil calculator, it
gives you every value you might want.
Many other issues - truss connections, 3 way truss per Lesson's
designs, wind load calcs, etc. My dipole truss is 2 phillystrans up to
a 5' wide crossbar 5' up the mast. So far no problems, but in a treed
area with modest wind loads. YagiMech predicts 85 mph survival w/o truss.
I'll send a coil picture offline.
Grant KZ1W
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