On Sat, 18 Jul 1998 08:23:42 EDT Mmoon3@aol.com writes:
>
>I have a copy of the Antenna Handbook, but would like to know current
>trends
>in non-resonant guy lengths. My guys will be about 55' long. Should
>I have
>about 3' at the top, then an insulator, then 14', then 14', then 27',
>then
>insulator, then anchor? Is this safe for 14, 21, 28 MHz?
14 ft is too close to a half-wave on 28 MHz. I use 12 ft,
insulator-to-insulator, 2 each, followed by 27 ft. lengths.
With guy grips, it is best to cut the lengths 1 ft shorter.
The first insulator needs to be as close as possible
to the tower (3 to 4 ft.) as you are planning. N4KG
>
>Does everyone use 504 insulators, or 502? I can get 504's from my
>local electrical supplier for only $4.55 each. I will be using 1/4"
guy
>wire.
The large (fist size) insulators should be used with 1/4 inch
guy wire.
>Should I use "genuine" Rohn 1/4CCF clamps (forged, hot dipped) or are
>the malleable ones OK?
AARGH! Most people have gone to using "guy grips",
actually called "dead-end's" in the industry. They
can be purchased individually from Texas Towers or
boxes of 50 (for 1/4 inch) or 100 (for 3/16 inch) from
Preformed Line Products Company in Cleveland, OH.
I have seen two towers fall over where guys pulled
through cable clamps that have worked loose. In both
cases, I believe there were only two clamps installed
and the cable was not "served" as shown in the Rohn
catalog. Serving 1/4 inch cable is a royal pain. Cable
clamps can work loose with time and need to be
inspected / retightened on an annual basis. Go back
and forth between the nuts as the first one will loosen
when the second is tightened. Just this year at Field Day
I found a loose clamp and the guy informed me he had
tightened them with a wrench. Obviously he did not go
back to the first nut. If you insist on using clamps, be
sure to use good quality galvanized clamps, 3 each.
Guy grips are a snap and cost effective. My guy grips
and 1/4 inch cable held up two 70 ft trees which fell on
them following a small tornado. Enough said? N4KG
>
>Thanks, 73,
>Mark N3AVA/0
>
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