AI1P Matt Steven wrote:
> Hello,
>
> I have a vertical antenna on a rooftop tripod that is guyed with
> stranded nylon rope. The rope naturally gets vibrating very heavily in
> wind probably due to its uneven surface and it really can sing.
>
I find that strange as I'm doing the same thing with no noise.
What size rop and how much tension are you using. Nylon is naturally
stretchy, but highly susceptible to weather and UV light. After a
couple of weeks it should get quite stiff with little stretch left. I
can't imagine the stuff being tight enough to sing/resonate.
I have been using 3/16" to guy an AV-640 which makes me ask, what is the
vertical? Is it a trap vertical, Aluminum tube, steel pipe, or tower
sections?
BTW, I'm replacing the guy line with some 3/16" braided poly rope which
has nearly twice the strength without the stretch or UV sensitivity.
The RFConnection has the 3/16" for less than 10 cents a foot and 5/16"
(1000# test) for 15 cents a foot. The 1/4" at 800# test is not as handy
with a core and separate jacket.
73
Roger (K8RI)
> The problem is that the house hook it ties to is anchored (necessarily)
> to a roof joist for support and these vibrations transfer right into my
> bedroom making for plenty of banshees on windy nights.
>
> What I've tried so far to dampen it:
>
> 1) Wrap the anchoring hook very thickly with electrical tape. little/no
> effect
>
> 2) Use scrap coax to absorb some of the vibration on the string as it
> comes in, before it touches the metal of the hook (acts as padding
> basically) little effect, the coax redirects some of the vibration but
> not enough to notice.
>
> 3) Same as 2 but running the actual tie-off to further down the roof,
> and just having the hook as a guide point. Not much effect.
>
> I can't afford Phillystran or anything really nice like that, so that's
> out of the question, but is there any way to stay on the cheap and at
> least get the vibration to stop resonating in the rafters?
>
> 73s,
> Matt
> ai1p
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