Date: Sat, 18 Sep 2010 11:14:31 -0700 (PDT)
From: Edward Sylvester <navydude1962@yahoo.com>
Subject: Re: [TowerTalk] 80-m. Inverted Vee vs. Dipole Performance
My experience is as follows:
I have a full-sized Inv Vee for 80m, fed with 600 Ohm Ladder Line, and through
a Tuner w/balun (apex at 70' and ends up 12').
My other antenna is a Create CD-75 Rotatable Dipole (shortened, 54' with coils
and capacity hats at the ends) up 75', in the clear.
I have A/B'd these several times, with domestic and DX stations. The Rotatable
Dipole wins every time, by 1-2 S Units, transmit and receive.
It's quieter, too. Doesn't have the bandwidth of the Inv Vee, but it has
switchable relays for the various segments of the 80m band and works fine on
75m, with tuner.
Just thought I would pass this along, staying on target with the topic.
73,
Ed NI6S
## N6BT, Tom Schiller, mentioned to me years ago, that his shortened rotary
80m dipoles would be at least 6db louder than an inverted vee, with the apex
of the
inverted vee, at the same height as the rotary dipole. Listening on 75m, I
would agree with this. The 80m rotary dipole folks always seem to clean house,
compared
to the inverted vee's. When they rotate them, I usually see abt 1 -S unit
F-S. Sometimes 2 -3 S units. The folks who have the rotary dipoles on 75m
tell me for
domestic stuff, [ 0-800 miles radius].. they typ see 1 S unit when they
rotate. However, on DX... it's usually 14 db..and a lot more pronounced.
Those compressible
coils made by Seco systems look slick. Then you can tune the entire
3500-4000 with flat swr. The coils they use are 1/4" Al, and black plastic
coated, [refrig tubing].
Apparently, folks with the older Linear loaded F-12 rot dipoles, have
successfully implemented the compressible coils, and removed the LL wires.
The LL wires are then replaced
with dacron rope... for the ele truss. Adding T bar capacity hats to the
older LL rot dipoles is also feasible.
Even a shortened rotary dipole is better than a full size dipole between 2 x
tree's. Now if you could put up 2 x dipoles..at right angles, and had enough
supports,
that will work good too. A fellow 25 miles north of me has just that....and
both are up 110' in tree's. When he toggles back and forth, it's a BIG
difference.
I'm 100% convinced that inverted vee's radiate omni directional. [ 90-100 deg
enclosed angle]. Unless the enclosed angle is a lot greater than 100 degs,
I just can't see using inverted vee els in any kind of fixed parasitic array.
later... Jim VE7RF
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