Dear Earl,
>.....coax feedlines and the rotator cable come down
>all the way to the ground ..........
I'm sorry for giving you my so-delayed question here.
Would you let us know your idea how "rotator cable come down
all the way to the ground",in fact?
73,Tosy - JE1TSD
|To: dz@VOA.GOV, topband@contesting.com
|Subject: Re: Topband: Re: Feeding the tower
|
|Andy, UA3AB wrote:
|
|"I need advise on how to make my tower to radiate on 160.
|
|Tower #1 is 42m (140 feet) high with 3 el short Yagi (Force12 Mag340N)
|atop it, Another antenna 5m(15feet) above it is 3 el 30m short Yagi
|(Force12 EF330).
|
|Another tower is 26m(90 feet) high with 6 el 20m and 6 el 15m Yagis atop
|it. May be this is a better choice?"
|==========
|Either tower can easily be shunt fed using the single-capacitor ("gamma")
|method.
|
|My choice would be the shorter 26m tower because it will be close to
|1/4-wave on 160m electrically with the top loading and therefore it will
|have a wider 2:1 SWR bandwidth and less RF voltage across the gamma
|capacitor.
|
|On my shunt-fed towers, I use either #8 AWG stranded wire or old RG-58
|coax for the shunt wire. They are both about the same diameter and their
|flexibility makes them easy to adjust. Some shunt-fed tower users build
|"cages" for the shunt feed wire, which slightly increases the 2:1 SWR
|bandwidth, but not enough to make it worth the extra cost and effort,
|IMO.
|
|Rather than elevated radials, I advise that you use many on-ground
|radials as the ground system.
|
|Also, make sure the Yagi coax feedlines and the rotator cable come down
|all the way to the ground before they leave the vicinity of the tower.
|
|73, de Earl, K6SE
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