Here's another way to measure the tension in you guy wires, and all you need
is a small tape recorder and 3 ft piece of 2 by 4 lumber.
Cut two small blocks off the ends of the 2x4, and nail them to the ends of
the long piece, on the side. File or saw a "v" notch in the small blocks,
along the long axis, so the guy wires can sit in the notches. This forms two
bridges, so that when the 2x4 is placed agains the guy wire, it can be
"plucked" to produce a vibration.
If you are erecting a Rohn 25 tower, the guys should be set to 400 lbs
tension (+- 50 lbs).
Now you need to "calibrate the instrument". Take a piece of the same guy
wire, hang it from any tree, tower, frame, swingset, anthing you can find
overhead that can support about 300 lbs. Form a loop in the guy to put your
foot in.
If you step in the loop and hang you will tension the guy to your weight.
(say about 200 lbs). While under tension, perhaps from a friend, place the
2x4 against the wire, and pluck it like a guitar string. Record the tone on
you tape recorder several times. Hint: placing the recorder directly on the
2x4 helps capture the tone.
Now, while you tension you tower guys wires, place the 2x4 against the guys,
and pluck them in the same way, listening to the tape recorded tone. When the
tension is the same as your weight, the tones will be equal. For the CW guys,
this is an easy thing to "zero" beat the tone.
If you want to double the tension to twice you weight (say to 400 lbs), the
tone will have to be twice the frequency. There are several ways to do this.
One is to make another bridge from a notched block of wood, and place it at
1/2 of the original separation distance. Another (if you have a sound card and
microphone) is to use your computer or other ham test equipment to measure the
frequency, and the produce one with twice that frequency with a tone generator
(many are free for the download). Record that frequency on your tape recorder,
and use it in the field for the 400 lb "note"
So for the cost of a 2x4, and a bit of time, you CAN "measure" the tension in
your tower's guy wires!
Chris-AI4MI
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