[TowerTalk] Re: TH7 Traps

[Jim White, K4OJ]

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 at contesting.com
> [mailto:towertalk-bounces at contesting.com]On Behalf Of n3drk
> Sent: Tuesday, September 09, 2003 4:38 PM
> To: Dan Levin; towertalk at 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 at andlev.com>
> To: <towertalk at 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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> 
> 
> _______________________________________________
> 
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> 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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