[TowerTalk] TH-7

[Peter Voelpel]

I am just considering the maximum possible stacking gain, not the different
elevation angles.

73
Peter

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Joe
Subich, W4TV
Sent: Samstag, 4. September 2021 01:37
To: towertalk at contesting.com
Subject: Re: [TowerTalk] TH-7


Take a look at HFTA using flat ground ...

A stack of 3 element yagis at 35/70/105/140 shows between 6 and 7.5 dB
over a single 3 element yagi at 70 feet between 2 and 11 degrees.  The
"crossover point" (where the higher lobe of the 70 antenna overtakes the
stack is around 16 degrees.  The "three stack" (35/70/105) advantage is
between 3 and 4.5 dB over a similar 2 to 18 degree range.

Since HFTA does not model mutual impedance effects, the relative
difference is the same if one substitutes 4 element for 3 element
yagis.

73,

    ... Joe, W4TV


On 2021-09-03 3:58 PM, Peter Voelpel wrote:
> With that stocking distance on 20m you will be lucky to get 3dB gain.
> 
> With 21m distance between 20m antennas you might reach 5.6dB
> 
>   
> 
> 73
> 
> Peter
> 
>   
> 
>    _____
> 
> From: jim.thom jim.thom at telus.net [mailto:jim.thom at telus.net]
> Sent: Freitag, 3. September 2021 21:10
> To: Peter Voelpel
> Cc: towertalk at contesting.com
> Subject: Re: [TowerTalk] TH-7
> 
>   
> 
>     4 x yagis  stacked is only 4db ?   Per the original article, it was a
> flame thrower.
> 
>   
> 
> Jim   VE7RF
> 
>   
> 
> On Fri, Sep 3, 2021 at 11:15 AM Peter Voelpel <dj7ww at t-online.de> wrote:
> 
> The stacking gain on 20m will be less then 4dB.
> 
> 73
> Peter
> 
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
> jim.thom jim.thom at telus.net
> Sent: Freitag, 3. September 2021 19:49
> To: towertalk at contesting.com
> Subject: [TowerTalk] TH-7
> 
> Date: Fri, 3 Sep 2021 09:59:46 -0400
> From: "Mike Ryan" <mryan001 at tampabay.rr.com>
> To: <TowerTalk at contesting.com>
> Subject: Re: [TowerTalk] TH-7
> 
> 
> <There was an op in Texas who mounted 4 of these on a rotating tower.
There
> <was an article in one of the ham magazines some years ago about it. But
it
> <was impressive. The TH7 has 5 elements on 10mtrs which soon will be more
in
> 
> ##  It was on the  front  cover of a  CQ magazine, back in the 80's.   He
> stacked em at  35-70-105-140'.   With all 4 driven in phase, he was  20 db
> louder than another ham, close by, who had just a single  TH-7 up  70'.
> I find that hard to believe, but that was what was reported.
> The article was entitled.... "TH-28".
> 
> Jim   VE7RF

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