On 9/3/2010 5:49 PM, Jim Brown wrote:
> On Fri, 3 Sep 2010 11:52:12 -0700, Dick Dievendorff wrote:
>
>> How would I figure this out?
> Ordinary engineering. :) There are, of course, several good ways to do
> it. My solution, for a 120 ft Rohn 25 guyed at 30, 60, 90, and 120 ft
> with a 3-el 20-6M SteppIR on top, was to buy 200 ft of Phillystran and
> use it only on the top set of guys (at the 120 ft level), starting at the
> tower, then transitioning to EHS. The other three sets of guys are EHS
> insulated from the tower and have egg insulators to break them up. That
> puts the nearest conductive guys at least 35 ft from the SteppIR, and
> sloping downward.
>
As I often ask...Why?
I'd use all Phillystran with the exception of the 10' at the base of
each line. It gives you more options and is so much easier to work with
than EHS. Almost no visible catenary. My 45G which is guyed with
Phillystran at 3 levels is rock solid even when the wind is blowing.
Also you don't have to be concerned about low frequency resonance.
Also the lower guys are likely to affect using it as a reflector.
Yes, the Phillystran is more expensive, but with a 120' tower and a
StepperIR on top I'd go the all Phillystran route and a ROHN 45G.
> I'm not loading the tower on any band, but I am using it as the reflector
> for a pair of sloping 160M dipoles.
Sloping dipoles on one 160 from a 120'? If full size dipoles they will
likely operate as if they are plain dipoles which is why you probably
see no interaction in the modeling.
73 and good luck
Roger (K8RI)
> I also have a 2-el 40M wire yagi on
> top. I think I'm designed for no interaction, and none has been
> identified.
>
> 73, Jim K9YC
>
>
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