Not a mechanical nor mathematical engineer but having had both TH7 and C31XR
my experience is that the C31 is much better, especially on 10 and 15 meters
and much easier to tune to WARC bands. No traps to service or replace
periodically.
----- Original Message -----
From: "Jim White, K4OJ" <k4oj@tampabay.rr.com>
Cc: <towertalk@contesting.com>
Sent: Friday, September 12, 2003 2:46 PM
Subject: Re: [TowerTalk] Re: TH7 Traps
> Folks - let's remember we are talking about a tribander covering a
> frequency range of X to 2X
>
> Since this equates to two different ideal boom lengths for 2 out of the
> three bands (not to mention the one in the middle!) obviously there is a
> compromise...
>
> The newer designs like those from Force 12 are essentially stacked
> monobanders staked 0'0" and sharing a common boom - they are interlaced
> monobanders...
>
> Because these newer approaches are more like multiple monobanders they
> are more likely to perform better than fixed element spacings forced to
> behave well over a large range of frequencies..
>
> NOW... Force 12, Bencher and the other "common boom" multi-band antennas
> have to contend with interaction of these elements...
>
> The winner is the one that best handles this, no?
>
> It is apples and oranges to me - the only thing the older era trapped
> tribanders have in common with the new era interlaced designs is that
> they both share the same idea - having on boom to turn with your rotor...
>
> The biggest upside of the newer designs which hasn't been fully tapped
> in my opinion is for the single op two radio crowd to perfect usage of
> these new era tribanders on multiple bands simultaneously with
> independent feeds - I can see a "Pacific Multiplier" or "Caribbean"
> antenna for 10/15/20 with three feedlines affixed to the side of a tall
> tower for that long path....
>
> Mebbe four years ago K3NA gave a good presentation on this at the
> antenna forum at the Hamvention...
>
> It seems interlaced yagis have the fewest compromises to design - if the
> designers can minimize interaction between the elements of the "other"
> bands...
>
>
>
> Rex Lint wrote:
> > john,
> >
> > I don't follow you.
> >
> > "One cannot dispute mathematics. Gain is a product
> > of Boom Length."
> >
> > The boom length of a TH7 is 24 feet. The boom length of a C-31XR is 31
feet.
> > Therefore, the C-31XR is the better performer according to your
mathematics,
> > isn't it?
> >
> > Rex
> > K1HI
> >
> > -----Original Message-----
> > From: towertalk-bounces@contesting.com
> > [mailto:towertalk-bounces@contesting.com]On Behalf Of n3drk
> > Sent: Tuesday, September 09, 2003 4:38 PM
> > To: Dan Levin; towertalk@contesting.com
> > Subject: Re: [TowerTalk] Re: TH7 Traps
> >
> >
> > And you could put some screen netting like a dxer did who made DXCC#1.
Yes
> > that is what he did and there is nothing wrong with your antenna. Dont
get
> > rid of the TH7 it is one of the best antennas out there even with all
the
> > hype of the so called unscientific tribander report. Save your money.
The
> > TH7 will outperform the c-31XR.
> > This debate has been going on since the 1960's. Stay with your TH7.
> > Dont get caught up in all this novelty stuff. The people who push these
non
> > trap antennas go by what is in that tribander report and like i said an
> > unscientific one at that. One cannot dispute mathematics. Gain is a
product
> > of Boom Length.
> >
> > john
> > ----- Original Message -----
> > From: "Dan Levin" <djl@andlev.com>
> > To: <towertalk@contesting.com>
> > Sent: Tuesday, September 09, 2003 2:39 PM
> > Subject: [TowerTalk] Re: TH7 Traps
> >
> >
> >
> >>>One of my TH7s started acting flaky recently, so I dropped the two
> >>>driven elements and took the traps apart.
> >>>
> >>>I wonder if anyone has a solution to prevent all this crud from
> >>>getting into the traps?
> >>
> >>Flame Suit On
> >>
> >>You could just get rid of the TH7 and get an antenna with
> >>no traps - like a C-31XR...
> >>
> >>Said with tongue firmly planted in cheek.
> >>
> >>Best 73,
> >> ***dan, K6IF
> >>
> >>See you all in the California QSO Party,
> >>October 4-5!
> >>_______________________________________________
> >>
> >>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> >
> > Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
any
> > questions and ask for Sherman, W2FLA.
> >
> >>_______________________________________________
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> >>TowerTalk@contesting.com
> >>http://lists.contesting.com/mailman/listinfo/towertalk
> >>
> >
> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> > Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
any
> > questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
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> >
> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
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> >
>
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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