[TowerTalk] DX86 vs. HDX589
Al Williams
alwilliams@olywa.net
Sun, 6 Aug 2000 21:49:54 -0700
I have just received a Triex LM470 motorized tower and three weeks ago I
purchase a used (~13 years) US Tower HDX-572MDPL motorized tower ($1000,
includes their work platform, several standoffs, mast, and a Cushcraft A4S).
Both are now laying on the ground so I have been comparing them. The US
Tower is a true level wind in that it has two jackscrews with cable guides
driven in sync with the cable drum. One jackscrew is for playing out the
cable and the other jackscrew is for reeling in the cable.
The Triex does not have any jackscrews and so any level wind must rely on
the tightness of the cable to cause the cable to move smoothly across the
drum.
Both towers have two cables (ends?) going simultaneously around the drum.
One cable is being reeled in while the other cable is playing out so I
assume both use positive pull down although I havent seen them in operation.
As to two or three cables--It is difficult to follow the cables while they
are
telescoped so I cant comment on that. I understood Joel at First Call to
say that there were two cables and if one broke, the other cable would keep
the tower from collapsing. I havent been able to confirm his claim by
inspecting the the system. However, I count ten lengths of cable traversing
from the bottom to the top for the Triex but only six lengths for the US
Tower. The cable in the Triex measures .196 inch whereas the
cable in the US Tower is .248 in diameter.
Hopefully, someone will explain how the cable(s) are looped that might
provide some safety.
k7puc
-----Original Message-----
From: K7LXC@aol.com <K7LXC@aol.com>
To: dave@dbtech.net <dave@dbtech.net>; towertalk@contesting.com
<towertalk@contesting.com>
Date: Sunday, August 06, 2000 5:58 PM
Subject: Re: [TowerTalk] DX86 vs. HDX589
>
>In a message dated 08/06/2000 4:37:32 PM Pacific Daylight Time,
>dave@dbtech.net writes:
>
>> > What does "appears to be a bit more sturdy" mean? Both towers were
>> >designed by the same guy - Lou Tristao - so they are slightly different
>> >designs. The only way you could tell which one was "sturdier" is to get
>the
>> >engineering calculations for each tower and compare them side-by-side.
>> Unless
>> >you're an engineer, interpreting the calcs might be semi-useful and the
>> >differences subtle.
>>
>> "Appears" to me means a three cable pull-up system and strong tubing. Of
>> course this is information from their literature and we all know how
much
>> salt to take along with marketing hype.
>>
> Okay, you still haven't cited anything - "appears" is just as ambiguous
>as it was before. What are the leg material, OD and wall thickness
>differences that make it "a bit more sturdy"? Specifics only, please.
>
>> > I'm not sure what a 'three cable system' is. I know the US Tower
has
>> >positive pull-down and I'm not sure about the Tri-Ex. Nonetheless they
>each
>> >have to have the appropriate number of cables to run it up (and down).
>They
>> >probably even use the same cable schemes.
>>
>> I know they claim to have a positive pull down, as well as a level-wind
for
>> their hoist drum.
>>
> Please let me know what a "level-wind" is.
>
>> >> Regardless of which one I finally choose, the tower
>> >> will be purchased with the raising fixture, but without the remote
>> control.
>> >> I see no need to spend a grand on a control box that can be easily
>> >> constructed. I also plan to fit the tower with an extra set of limit
>> >> switches in series with the provided ones (I want to be able to
>operate
>> the
>> >> tower automatically during bad weather with some peace of mind).
>> >
> ERRRRR! You just validated your factory warranty!
>
>> > I'm not a big fan of remote controlling the raising and lowering of
a
>> >motorized crank-up. I know personally of several calamities that have
>> >resulted from not being able to watch the tower as it was raised or
>lowered.
>>
>> >Extra limit switches won't solve this problem.
>>
>> That's too bad. I won't purchase a system that I can't trust to work as
>> advertised.
>
> They're advertised that they will fail during unattended raising or
>lowering? I'll bet you a nickel that their literature stresses the
opposite.
>
>> The extra limit switches are just for the extra safety margin.
>
> They'll protect you when the coax gets hung up or an antenna or wire
>snags on the roof?
>
>> So are you saying that motorized towers fail on a too frequent basis or
was
>> there some issue with the respective installations?
>
> What I'm saying is that a crank-up is a complicated mechanical device
and
>should only be raised or lowered when the operator is actually observing
it.
>I've seen a number of failures, many caused by their owners, consisting of
>the coax hanging up, something accidentally left in the tower causing one
of
>the section lifting cables to part or something else getting hung up.
>
> What I'm saying is that by following obvious safety procedures and the
>instructions from the factory you will have a reliable, longterm
>installation. The opposite is also true.
>
>Cheers, Steve K7LXC
>Tower Tech
>
>--
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>
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