Ignacy,
The Rohn specs allow for two sets of guys on 100 feet of Rohn 45 in its lowest
wind-zone rating. Upper guys (at 85 feet) are 1/4" EHS and lower are 3/16" EHS.
In higher wind zones three sets of guys are specified.
http://www.rohnnet.com/files/2015_Rohn_Full_Catalog.pdf#page=48
I've had such a tower with two sets of guys here in central Delaware for the
past 21 years, with a 3-stack of HyGain 204BA yagis on it. The guys are
insulated EHS steel. I've never found any problem with the lower beams
interacting with the guys.
I have successfully shunt fed several Rohn 25 towers with insulated EHS steel
guys. Some have had a 6-foot section of EHS connected to the tower before the
first insulator, others used a bent pin shackle to place the first insulator
right at the tower. I haven't noticed any difference with either method.
Nonresonant insulated guy lengths used typically are 58 feet or 39 feet, taken
from a chart in the ARRL Antenna Book.
At this QTH I have a 119-foot series-fed Rohn 25 for 160m, which started with a
combination of Phillystran and insulated EHS guys. When trees grew and risked
chafing of the Phillystran guys, I replaced those with insulated EHS steel, and
I didn't see any change in tuning or performance.
Phillystran is a great material if the tower is in the clear and there's no
risk of chafing from tree branches. Do use a length of steel at the bottom 10
feet or so of each guy, for ease of adjustment, fire safety and vandalism
prevention. DX Engineering sells a nice kit for those tails.
If in doubt on any phase of your plans, consider hiring a structural engineer
to review them. You may need this anyway to obtain your local building permit.
73/Jon
Jon P. Zaimes, AA1K
Tower climber for hire
http://www.aa1k.us/
Cell: 302-632-2353
Reviews of AA1K tower work on eham website:
http://www.eham.net/reviews/detail/12922
Hug your favorite tower every day, and always stay connected to it.
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Jeff Blaine
Sent: Monday, December 16, 2019 7:14 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] 45G and guys
On the question of "Will the EHS cause interactions" - the answer is YES.
That is true regardless of length, although the magnitude of the interaction is
going to be a factor of many things including the length and proximity. It's
possible to pick lengths that minimize the impact depending on band, etc.
So if you plan to mount a beam among the guys, definitely use insulated guys
like the Phili stuff as that takes interaction problems off the table for the
most part.
Good luck!
73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com
On 12/16/19 1:27 PM, john@kk9a.com wrote:
>
> You should do your homework before trusting any installer, this
> information is readily available. Rohn's catalog will clearly answer
> your question regarding guy locations and the EHS type. This varies by
> wind speed and wind load. If you are going to have side mounted
> antennas I would definitely use all non-metallic guys. See the
> Phillystran catalog for the equivalent kevlar cables and proper
> installation techniques.
>
> John KK9A
>
>
>
> Ignacy Misztal no9e wrote
>
> I want to have a 100ft 45G installed on my new property. It will hold
> JK Mid Tri 40 on top. I plan on adding a Yagi with a swinging gate at
> lower level later, and perhaps shunt loading for 160 and 80m.
>
> My installer wants to use 3 sets of EHS wires. He is ready to
> substitute the top one with Phillistran. So here are my questions:
>
> Are EHS guys likely to cause interactions with top and medium beams?
> Do EHS guys compromise tower for 160M shunt feeding?
> Do I need 3 sets of guys?
> Should I move to Phillistran?
> Is Phillistran 7000 lb on top and 4000 at bottom good enough?
>
> The installer wants to build the tower with the beam on top. Have the
> beam at 3 ft, then raise to 13, 23,....Perhaps that's why 3 sets of
> guys. The location is in E GA, with relatively low wind.
>
> Ignacy, NO9E
>
> _______________________________________________
>
>
>
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