Date: Tue, 24 Feb 2015 08:19:49 -0600
From: Kelly Taylor <ve4xt@mymts.net>
To: "john@kk9a.com" <john@kk9a.com>, <towertalk@contesting.com>
Subject: Re: [TowerTalk] Mosley Antenna Question
Great, now people are going to accuse others of TH7DXX-bashing... ;=)
The TH7DXX is obviously a successful product of its pre-modelling era. Lots
of people have had success with it. So this isn't bashing it, OK?
But it's surprising how many people seem to want to refuse to believe the
antennas they grew up with could have been surpassed by modern technology.
(KK9A, this comment isn't necessarily directed at you.) The thing about the
TH7DXX is, with all its aluminum, weight and windloading, it's just a
three-element antenna on 15 and 20.
(On 10m, it's a four-element.)
If you look at the manual, the maximum gain on 20 is 8.0 dBi. So take off
2.15 dB right there, and then consider the added gain for marketing
purposes, and then consider it's the maximum gain only, which would be at
the absolute sweet spot in the band.
Suddenly, it becomes a bit easier to believe it's outdone (or at least
equalled) by a smaller, computer-modelled, trapless interlaced
multi-monobander (to use an N6BTism).
Does the TH7 work? No question. Is it now the best use of aluminum? That's
up to the purchaser.
73, kelly
ve4xt
## The hy gain 204BA is 4 el on a 26 ft boom. Eznec and YO etc, etc, all
show 6.0 dbd gain..or 8.15 dbi.
Th7-dxx... 8.0 dbi on 20m....... I don’t think so. A 203BA is only 5.2 dbd...
or 7.35dbi . Nice try though.
## These folks making trapped yagis cant post a eznec plot of gain vs
freq....simply cuz there is no way to model it in eznec.
## For everybody else building non trapped yagis, monobanders, multi
monobanders etc..... at least provide a graph
of gain vs freq..and ...... FB vs freq...and ...... FR vs freq..... FS vs
freq.....and the usual swr vs freq.
Some of these yagis don’t hold a pattern across the band.
## check out some of the latest offerings from JK ants and also M2 / inovate
ants. Multi band yagis on really short booms.
Jim VE7RF
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