Making the gross assumption that you can drive a substantial three or four
foot stake a foot or so into the ground or find a suitable fence post or
railing to tie the base of one of the collapsible masts to, why all the fuss
re guy anchors. I've always found that my 40 foot collapsible fiberglass
mast with a center fed vertical dipole taped to it was quite capable of
standing up on it's own in winds up to what I would guess to be at least
20-30 MPH. If guys should be necessary just put a hose clamp on the mast at
half to three quarters of the way up, to keep the guys from sliding down,
take a good guess at the length needed to run a guy at about 45 degrees, and
cut three pieces of the 1/8 inch light rope you brought along for just such
a case. No need to make a big engineering project out of it. The guys can be
tied off to anything available or to the simple tent stakes you also just
happened to bring along. Even with the wire and fifty feet of 450 ohm
ladder line, your transceiver and power supply will all fit in a small box
or suitcase, can be deployed in less than a half hour and will let you have
lots of fun on the air with your own little expedition.
Gene / W2LU
----- Original Message -----
From: "Jim Lux" <jimlux@earthlink.net>
To: <towertalk@contesting.com>
Sent: Saturday, February 02, 2013 2:57 PM
Subject: Re: [TowerTalk] Fwd: Fwd: Temporary tower/antenna question
On 2/2/13 11:39 AM, Brian Alsop wrote:
I guess the rest of the earth is flat. With the uneven terrain around
here no way pre-cut guys would work. Also there is a likelihood that
where you try to screw in an anchor, you can't because of rocks, roots
or whatever.
Sandbags or lead shotbags are your friend. You get it close, hoist away,
then move them in or out as needed.
yeah, they drag on the surface, but it's a temporary install.
A back of the envelope shows that a 40 foot mast 2" in diameter would have
a wind loading of about 16 lb in a 30 mi/hr wind. Using my guy anchor at
half the height scheme, the "dragging force" is only about 8lb (half the
force is on the base of the antenna, half at the top), although the
lifting force is twice that. You need a pretty heavy anchor to hold it in
place, so it's gonna slide. (you need at least 24 lb to hold, if friction
coeff is one). My sandbags are about 10 lb.
To stabilize things, I've piled rocks on the sandbag, for instance. I
think a 5 gallon water jug might work well, but you need to carry water
then (or be able to fill it on site, which takes time).
And I'm not real interested in carrying 100 lb of sandbags or lead shot
around.
But in a 15 mi/hr wind, the load is about half the load at 30 mi/hr.. so
that's getting more reasonable, and to be honest, 15 mi/hr is fairly
windy. If it falls over in a Santa Ana... oh well.. it's not so heavy
that anyone will get hurt.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|