Joe Spinosa wrote:
>
> This may seem like a simple question, but it has really been nagging me
> lately.
>
> I'm close to finally erecting a modest tower. Its going to be a US Tower
> model TMM433HD. This is a whopping 33', heavy duty crank-up. (I know it's
> not much, but believe me, it has been hell just getting this approved).
>
> It looks like US tower is using 4 ten foot sections. What everyone (neighbors
> and city) likes about this model is that it nests down to about 12'.
>
> I'm trying to build a satellite station. There will be a couple of crossed
> yagi's with the typical azimuth & elevation rotation configuration.
>
> Here's the question: How do people route rotator control cables and coax runs
> on crank-up towers? Are the coax runs supported on each section?
>
> Initially, I'll probably have to be cranking this thing up and down quite a
> bit. Don't tell my neighbors, but as time goes on, and everyone gets used to
> the tower being a fixture in the neighborhood, it may stay fully extended for
> longer periods of time. You get my drift.
>
> Anyway, we VHF/UHF weak signal and satellite guys are fond of station
> improvements like hard-line coaxial runs etc. I'm wondering what happens to
> coax runs when you collapse the tower. Does everything just sort of flop
> around the yard?
>
> Since the tower is only 33', and the ham shack/observatory will be right next
> to the tower, I'll probably only require short runs of coax. 50' should be
> enough, from antenna connector to radio! Therefore, I may not really need
> fancy, and heavy, and expensive, hard-line. I could wire the whole works with
> flexible LMR400 or the new Belden 9913F, and not really see too much
> degradation, even at 440MHz.
>
> I'm thinking I can route the rotators' (there will be two AZ/El) control wires
> inside the tower. I suppose it would all just sort of bunch up when you crank
> it down. Not too professional.
>
> I assume the coax runs will have to be supported outside the tower somehow.
> What will that look like when cranked down? Will this incessant cranking up
> and down put unusual wear on things like coax runs? (Not to mention winch
> cables and pulleys etc.)
>
> Hmmm, reading over this post it occurs to me that I may have miss-lead you. I
> really did start out with one simple question. It just blossomed. I can't
> help it.
>
> Anyone have a neat looking crank-up that actually looks NEAT when its cranked
> down?
>
> Best Regards,
> Joe Spinosa
> KF6CWX
> Concord, CA
>
> --
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Glad to hear you are getting the project underway. I have exactly same
concerns regarding cabling the crank up for my TX489MDPL I am in process
of erecting. I will also be using mine for satellite work and I have
been studying the problem of getting decent ERP after a 90 to 100 foot
length of flexible cable. The receive side is not much of a problem
since I have the ICOM AG25 and AG35 preamps with 15 dB gain. I am
planning to put a power amplifier for each band (144 and 432) at the
base of the tower. Since the ICOM preamps are good for about 100 watts,
my goal is to get that much up the tower if possible. The LMR400 Flex
seems to be a little stiff for repeated use, forget about Andrew
Superflex, it is designed to "look pretty" when dressed into a site, but
the cable to connector interface is weak. Repeated flexing will cause
failure of the shield and will deform the cable and increase loss, 9913
looks more promising with lowest loss, lowest cost, however reports are
that it degrades with moisture. The last sample of 9913 I looked at was
some time ago, but I think it also was pretty stiff. I will probably go
the 9913 route, and if that fails I will revert to some high quality
teflon RG8 style cable I picked up on the cheap, it is a bit lossier
though, 4.4dB/100 vs 2.7dB/100.
I hope someone else has a better solution!
--
Joe Leikhim
Jleikhim@nettally.com
"tv dinner by the pool,
i'm so glad i finished school" -F.Zappa 1967
"The Revolution will NOT be televised" -Gil Scott Heron
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: K7LXC@contesting.com
Sponsored by Akorn Access, Inc & KM9P
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