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Guy Wire Equalization of Force?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K7GQ, Jul 2, 2020.

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  1. K7GQ

    K7GQ Subscriber QRZ Page

    I'm confronted by a situation that requires me to add guy wires to my short 40' Rohn 45 tower. As this tower is at the back corner of my property, guy wires will not have the same spacing - measured from the tower base - meaning that the angle of each guy wire sloping downward will be unique. What can be achieved is a 120 degree spacing between the guys.

    Is there a methodology that assures an equal guying effect though the actual downward force will be unequal owing to the variety of guy wire angles?

    Thanks in advance

    Harry
     
  2. WB8NQW

    WB8NQW Ham Member QRZ Page

    Put a level on the legs and make sure the tower is vertical.
     
    AJ5J, AG6QR, N5YPJ and 2 others like this.
  3. KU3X

    KU3X Ham Member QRZ Page

    The distance from the base to each guy anchor on my tower is not the same. Like what WB8NQW said, make the tower plumb and that's it. My tower has been up for 38 years...83 feet to the top with two stacked yagi's on top.
    Barry
     
  4. WR2E

    WR2E Ham Member QRZ Page

    Doesn't Rohn specify that 45G can go to at least 40' freestanding (with proper base?)
    Is the building department requiring this for some reason?

    As in THREE equally spaced guys?

    I can't see the tower in the aerials.
     
  5. K8ERV

    K8ERV Ham Member QRZ Page

    Not sure I understand your situation, but I have seen a gadget that measures (indicates) the wire's tension. Think it forced a kink in the wire and measured the displacement amount.

    If this would work maybe you could find a friendly commercial installer and borrow his.

    TOM K8ERV Montrose Colo
     
  6. K7GQ

    K7GQ Subscriber QRZ Page

    There currently exist no guys but the plan is to add them. The guys will be equally spaced but not equidistant from the tower base. The tower isn't particularly visible in the satellite photos but a sharp eye will eventually locate the boom and several elements of the Steppir yagi.

    I am aware of a strain gauge that can be used for sail rigging but I had hoped to not employ wire guys.

    No. The tower is currently house-bracketed at two levels - the lower level is damaging the inside wall in that area - presumably from the tower flexing in big Nevada winds and imposing a strong force on the lower bracket.

    It's currently plumb but your advice is helpful and easy to implement - thanks!
     
  7. KC8QVO

    KC8QVO Ham Member QRZ Page

    Free standing with no wind = ensure the tower is straight up and down as you tension the guy lines.

    In high winds = considering the same wind speed from all directions here (theoretical), same anchoring height on the tower, and equal angles around the tower - the guy line with the shortest distance from the base of the tower will have the highest force, as will the anchor. The converse is also true - the wind pushing from the side with the short guy line will transfer more weight down to the base of the tower.

    Something worth considering is the strength of the short guy, its hardware, and its anchor in the ground.

    Another thought - you do not want banjo string tight guy lines. The tower should move in the wind. If it doesn't move you have a problem, just as you would if it moves too much and collapses. There should be some play in the guy lines as they load up force in winds. If there is no play in the lines they are over-tightened to begin with and at a higher risk of popping. With guy lines in that configuration (given 3 guy lines here) - over-tightened - the two tight guy lines still attached to the tower after the 1st breaks will pull the tower. Then you have both the wind force AND the sling-shot of the 2 tight guy lines in cahoots to send your tower to the ground. I certainly would not want that to be my tower, but I have to admit I would enjoy seeing a demonstration of that failure in action (like a scale wind tunnel test etc).
     
  8. KD0CAC

    KD0CAC Ham Member QRZ Page


    " As this tower is at the back corner of my property "
    The general idea is that if the tower falls --- it can not land outside of your property lines , ------ and defiantly not reach any structures , let alone people , pets etc.

    " Is there a methodology that assures an equal guying effect though the actual downward force will be unequal owing to the variety of guy wire angles? "
    As tension starts to apply to the tower , you need to check , with some method of the tower maintaining straight & pump , it's common that when the guys are 1st attached at the ground points that the tower will be pulled out of " straight " - so without over tightening - you add tension to the guys to straighten the tower , you can do this either with a surveyors transit , or like sighting down a joints to see how straight it is and make sure the crown is facing up .
    So putting one eye up each leg to sight straight .
     

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