On 10/6/2012 4:44 PM, SPWoo wrote:
Hi Larry,
Thanks for the reply. I get a lot of wind here and I'm afraid that the
counterweight would swing in the wind and cause stress on the rope/wire. I
wonder if there's a device that would retract the wire on a reel. Since I
retract my tower after I'm done with each operating session I need an automatic
device where I don't have to make a trip to the outside. I do have one of
those coax arm supports already on the mast.
My tower is also loaded to the max. so a rotatable dipole is out of the
question. My other options are to mount the apex at the top of the bottom
tower section, or to shunt feed the tower for 80m.
A couple of things to think about when doing something like this.
Because it's an Inverted-V letting the tower down does not mean you need
to take up that much slack from the antenna.
You can use a block and tackle arrangement so the support rope enters
the block and tackle. IE used the block and tackle backwards for a
2,3,o4 4:1 take up. You can use and really need to use a heavier counter
weight for this approach.
Treating the counterweight separately it can be kept inside a pipe,
Steel channel, square Aluminum or steel tube, or even wooden enclosure
where it either hangs free or slides within the enclosure.
Take up reels: Instead of counter weights you can use spring loaded take
up reels or even take up reels powered by weights, or actual powered
take up reels that would activate when ever the tension was released by
letting the tower down.
You can also use the stretchy rope from the anchor point out to the
antenna ends.
OR you can use a combination of these approaches.
Let your imagination be your guide.
Ask others in the area. Some suggestions will be a bit impractical like
the dual wishing wells, to outlandish, to actually useful.
Much of this would not work for me as my antennas are under several
hundred pounds of tension to keep them at least some where near straight
as the centers support close to 100 feet of LMR400 and relatively large
current chokes consisting of 5 2.4" #32 cores with 5 or 6 turns of Davis
BuryFlex(TM)
73 and good luck,
Roger (K8RI)
Best Regards,
Jonathan Woo
(970) 646-1711
________________________________
From: Larry Loen <lwloen@gmail.com>
To: SPWoo <jj_2_woo@yahoo.com>
Cc: "towertalk@contesting.com" <towertalk@contesting.com>
Sent: Saturday, October 6, 2012 1:58 PM
Subject: Re: [TowerTalk] Inverted V on a retractable tower
I have seen this very thing done.
Basically, you need some sort of extender (if you're talking about US Tower,
they sell such a device) so that the summit of the inverted V clears the tower
sections.
Then, you just need to have some sort of system at the ends of the antenna that
amount to some fairly simple pulley system with weights to allow the wires to
fall down when the tower is cranked over for service.
On a tower at W0IBM, I saw something like a commercial product that did this. It was
tubes of maybe 2 inches in diameter attached to courtyard walls (the tower was in a
courtyard). When the tower came down, the weight-and-rope at the end of the wire antenna
retracted into the tubes well enough. We could detach or keep the thing intact from the
top of the "V" when we tilted it over. I believe we typically detached it for
service; the system was designed such that
the wire was simply "where it needed to be" when the tower was retracted (but
not cranked over) so we could reattach it
after we cranked the tower back from horizontal to vertical.
At my forever under development new shack, I plan to do something similar with my US
Tower retractable. I have an old trick of putting conduit over rebar as a distant
antenna support for simple wire antennas. I'll probably resort to the same
weight-and-pulley trick -- I may even settle for a simple "eye hook" instead of
bothering with a pulley.
The nice thing about the rebar-covered-by-conduit is that while it is plenty
stable, it is easy enough to simply lift the conduit off of the end of the
rebar (the fit is tight, but not overly so). So, everything is serviceable.
With my simpler scheme, the wire may end up on the ground, but most of it would
be away from the tower and, I presume, easy to manage without kinking and
coiling.
If I discover I can manage 20 feet of conduit with my scheme, then it is more
like the W0IBM installation, because it would be at about the same height as
the retracted tower.
Larry Wo0Z
On Sat, Oct 6, 2012 at 11:29 AM, SPWoo <jj_2_woo@yahoo.com> wrote:
Hi All,
Does anyone know how to install an inverted V antenna for 80m on a retractable
tower? Is there anything that could be done to prevent the wires from laying
on the ground when the tower is retracted? Thank you and 73.
Best Regards,
Jonathan Woo
(970) 646-1711
_______________________________________________
_______________________________________________
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
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|