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[TowerTalk] Mosley antennas -

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Subject: [TowerTalk] Mosley antennas -
From: (David L. Thompson)
Date: Thu, 12 Feb 1998 20:52:56 -0500 (EST)
Gus VO1MP is right on when he says...

>the classic 36 or the pro37 do not match the TH6DXX, and in fact for all
>that additional aluminum does not seem to buy you anything over the
>Venerable Classic 33

The TA-33 series was designed when antenna theory was available, but there
was no way to really know if the real world result was close to "suspected"
specs unless you tested it out on a test site.  Carl Mosley ran comparisons
to a dipole and knew the TA-33 was good on F/B but low on gain.  The Classic
33 (18' boom) retained the excellent F/B but increased gain by nearly 2 dbi.
The Cl-33 beats the TA-36/CL-36 and runs close to the TH6 on 20.

I remember testing out a Gonset Tri-Bander (Yes Gonset made the forerunner
to the KT34) in 1959.  It was on an 18 foot boom with 3el on 20/15/10.  As
with the KT34 the low band is 15.  W5KHB came over and we set up a test
dipole 150 feet away with a calibrated DB meter.  WE pointed the beam at it
and then away trying for max gain while maintaining decent F/B (W5KHB had a
4el 15 on a 29 foot boom that was a killer!).  On 20 we got 5DBd and 24DB
F/B.  On 10 we got 5dbd and 21 db F/B.  On 15 we got 5dbd with almost no F/B
or 3.5Dbd and 16 db F/B.  BTW The 4el 15 at W5KHB got 7.6Dbd gain and 34db

A friend (Arnold WA4MIV) had a CL-33 up 110' back in 1969 when I would come
to Atlanta.  That thing played!!!!!!

But putting a lot of aluminum, on a boom can be counter-productive.  I
remember when the long boom 2 meter antennas were popular 25 years ago.
Someone (may have been Mike K6MYC) tested several and found one popular
brand was nearly 1 db better of the back!

My guess is that after Carl died and the new ownership took over that they
just started slapping elements on the booms...maybe they will now run each
on a modeller then find a test site (Scientific Atlanta has one..).  I
suspect with some work they can make antennas (outside the old TA-33 series)
that work.... 
Dave K4JRB

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