Date: Tue, 9 Aug 2016 06:57:06 -0400
From: "john@kk9a.com" <john@kk9a.com>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Stacking question
There is a lot of information about stacking in books such as W2PV's Yagi
Antenna Design.
John KK9A
## take the w2pv info with a grain of salt. In one of his lectures, he put
the top 20m yagi
at 150 ft. Then tried the bottom yagi at 65/75/85 ft. On his software, the
gain peaked with
bottom yagi at 75 ft. The premise was, the bottom yagi was placed midway
between top yagi...and
the dirt ! IMO, if the top 20m yagi was instead at 200 ft, you would not
place the bottom 20m yagi
at 100 ft...more like 130-140 ft. Then w2pv tried modeling a 3 high stack,
at 150/100/50..which smoked everything.
## stick with HFTA, and enter everything correctly. If you plan on buying
450 ft of tower, instead of
3 x 150 ft towers, have at least one of em up 190-200 ft . A buddy has a
3 x stack on 20m on his 190 ft
rotating tower. Then a 2 x stack on both 15m..and also 40m. ( 40m is
90/180 ) Then a 2 el 80m yagi at 190 ft.
Ok, then you can really smoke on 80 /40 /20 /15m. The 2 stack on 40m is a
flame thrower. The 3 stack on 20m is
a flame thrower on steroids. 2 el on 80m at 190 ft is pure gravy...loads of
gain, quiet, lotsa FS...and good FB.
Then single yagis on 6/10/12/17. It all fits on a single 190 ft rotating
tower.
## But it all has to be designed for local WX. IE: factor in expected max
wind speed and any possible icing.
Rotary towers are great... except everything is pointed in the same direction.
With ring rotors etc, its a real
advantage being able to point each 40m yagi..in a different direction. Then
u get to blast away..in 2 simultaneous
directions. But it all depends on the application, location, DX mode, fun
mode, MM or MS mode etc.
Jim VE7RF
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