Someone posted here a while back that some UST crankups not
only have positive pull down, but also continuous height readout.
I think it was marketed to commercial users who needed to set the
antenna at a specific height as a test. However, this readout is an
additional check that everything is OK. (Analogous to rotators that
detect if they are actually rotating, and if not, they time out). As
is the case with the rotators, it does not cover every possible failure
mechanism.
You could probably homebrew a height indicator by gluing a magnet on the
winch pulley, and detecting it with a reed switch. The reed
switch would drive an MFJ screwdriver antenna controller. You
could even program the MFJ to ten different preset heights.
Another safety device would be a tension indicator on the coax
at the attachment point at the top of the tower. This tension
should never exceed the weight of the coax plus a small allowance
for friction.
I have tried to imagine some sort of positive pull down for the
coax, but every way I have considered has some drawbacks.
Regarding night work: you can now get a 30 million candlepower
(that's right 30 million) "flashlight" at Costco for about $25.
I have used one of these at night with binoculars to look at
the coax at the top of my tower. You can basically see everything just
like in daylight. This "little" flashlight can also clearly illuminate
my 2 inch diameter vertical antenna 1000 ft away to verify it
hasn't blown down.
Rick N6RK
Edward Sylvester wrote:
> Amen....It's happened to me. Not safe unless there is absolutely positive
> pull down. I experienced this nightmare at night and saw the tower
> sectiones come crashing down. Could have lost a limb.....
>
> In my case, it was a Hygain HG-72HD. I recovered the tower and recabled
> it. Still had the same problem with it getting stuck in the up
> position. I attribute this partially to there being no load on it, as I
> had not yet installed the rotor, mast or antenna.
>
> It's been many years, but I have a second Hygain (same model) that I
> plan to install. Hope I don't experience the same thing. Anybody have
> this happen to them with a Hygain tower? Any advice??
>
> Thanks again.
>
> Ed NI6S
>
> K7LXC@aol.com wrote:
>
> In a message dated 9/14/2006 1:34:05 P.M. Pacific Daylight Time,
> towertalk-request@contesting.com writes:
>
>> I have a Tri-Ex LM-470 motorized crank up tower. I would like to be able
> to
> remotely control it from my ham shack. The only remote control system that
> I
> have been able to find is the original system that was offered by Tri-Ex.
> My
> concern with that system is that it uses (GASP) vacuum tubes to provide
> the
> delay required when changing directions. Does anyone out there have a
> schematic or other information on a more modern design? I have the
> facilities to fabricate anything needed, or I would be willing to purchase
> an existing system. Any suggestions?
>
>
> Yeah, don't do it. The only way to insure that a crank-up goes up or
> down successfully is to be in the direct vicinity - preferably standing
> next
> to it - watching it as it's moving. Otherwise a cable can snag and the
> result can be breaking a haul cable and watching the whole thing crash
> down.
>
> If you can see it from the shack (what happens at night?), you'll
> probably be okay but you still probably aren't close enough to watch
> everything.
>
> I've seen a couple of crank-ups where this has happened and it was
> just some cable getting hung up producing a major problem.
>
> Cheers,
> Steve K7LXC
> TOWER TECH
> Cell: 206-890-4188
> _______________________________________________
>
>
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