[TowerTalk] 45G and guys

[Jon Zaimes]

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 at contesting.com> On Behalf Of Jeff Blaine
Sent: Monday, December 16, 2019 7:14 PM
To: towertalk at 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 at 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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