[TowerTalk] Attaching "flex" cable to crank-up standoffs

[Dick Green WC1M]

Patrick,

I'll be happy to share details of my installation. Might have some photos as
well. But first, what kind of crankup tower do you have or plan to have?

73, Dick WC1M

> -----Original Message-----
> From: Patrick Greenlee [mailto:patrick_g at windstream.net]
> Sent: Thursday, May 16, 2013 6:38 PM
> To: Dick Green WC1M; 'Marv Shelton'; K8RI
> Cc: towertalk at contesting.com
> Subject: Re: [TowerTalk] Attaching "flex" cable to crank-up standoffs
> 
> Dick  would you mind sharing your coax installation details. I am
> interested in remote raise and lower for an automated crank-up tower
> with an eye toward NOT being out at the base of the tower lowering  it
> as a thunderstorm approaches.  I am interested  in "FAIL SAFE" operation
> that does not need observation, even remote observation.  You are a ray
> of sunshine on this topic as I got beat up pretty thoroughly for
> mentioning the idea of unattended raise/lower of an automated crank-up
> tower previously.
> 
> Thanks in advance for your consideration.
> 
> Patrick AF5CK
> 
> 
> 
> -----Original Message-----
> From: Dick Green WC1M
> Sent: Tuesday, May 14, 2013 2:44 PM
> To: 'Marv Shelton' ; K8RI
> Cc: towertalk at contesting.com
> Subject: Re: [TowerTalk] Attaching "flex" cable to crank-up standoffs
> 
> When I installed my 72' rotating tubular motorized crankup back in 1997,
> I used LMR400UF. Big mistake. IMHO, that stuff is so stiff it shouldn't
> be called "flexible". There were a number of issues with dressing the
> coax on the tower that were due to total lack of instructions from U.S.
> Tower, but the long and short of it is that the LMR400UF was so stiff
> that a big loop of it "crept" around the tower while it was being
> lowered and got caught in the motor mounting brackets. Next time I
> raised the tower, the coax snagged on the brackets just before the tower
> reached full up. The tower proceeded to lurch violently back and forth
> in a sickening manner in the second or so before I realized what was
> happening and hit the power switch (I was in the shack at the time, 265'
> away, watching through a window.) I ran to the tower and found, much to
> my relief, that the plastic balun housing on the TH-7 had exploded,
> which freed the SO-239 and the coax before the raising cables snapped or
> the pulleys or the motor were destroyed.
> 
> I reconfigured the standoffs and bought an extra one to put below the
> motor so the coax couldn't possible get snagged again. I also put a
> hardware cloth cage around the base to keep the coax away from the
> rotor. Most important, I replaced the LMR400UF with RG-213. I have had
> no snags since. I'm completely confident in raising and lowering the
> tower remotely without seeing it.
> 
> Some years later, I ran some flexibility tests between Buryflex,
> LMR400UF, Belden 9913 and RG-213. It was no surprise that the 9913 was
> too stiff for the crankup or rotor loops, nor was it a surprise that the
> LMR400UF came in a distant 3rd. What did surprise me was that the
> Buryflex was almost as flexible as the RG-213, and the jacket was much
> more slippery -- perfect for gliding through the coax standoffs on the
> crankup (I don't attach the coax to the standoffs because it results in
> all sorts of twisting and snagging.) Anyway, I replaced the RG-213 with
> Buryflex and it has performed perfectly ever since. I can't recall how
> long it's been, but I'm sure it's at least 10 years. Maybe more like 15.
> 
> Incidentally, I used LMR400UF for a number of runs on the ground, like
> the feedline to my 40m 4-square. That was problematic, too, because it
> seems that the critters on my property love to munch on the jacket
> material. I had to replace that particular 100' run, and several others,
> countless times.
> Then I replaced the runs with Buryflex and haven't had a critter problem
> since.
> 
> YMMV
> 
> 73, Dick WC1M
> 
> > -----Original Message-----
> > From: Marv Shelton [mailto:marvs at att.net]
> > Sent: Tuesday, May 14, 2013 8:10 AM
> > To: K8RI
> > Cc: towertalk at contesting.com
> > Subject: Re: [TowerTalk] Attaching "flex" cable to crank-up standoffs
> >
> > So, what do you think is best? RG-213???
> > I think getting 5 years out of low loss coax is acceptable. I can help
> > force at least that interval of mainten ance on one's amtennas.
> >
> >
> > Best 73's
> > de Marv WA2BFW/7
> > (from my iPad)
> > >
> > > LMR 400 is not recommended for repeated bending. It has a Copper
> > plated solid Aluminum center conductor.   OTOH LMR-400UF is very
> > flexible but does not normally stand up well to out door use. The
> > jacket is a rubber like material that is easily abraded, catches on
> > most any thing and has a short advertised life of 10 years.  Best I've
> > gotten out of using it in normal situations has been around 6 years.
> > It works very well, but not for long.
> > >
> > > 73
> > >
> > > Roger (K8RI)
> > >
> > >
> > >>
> > >> 73's from Marv
> > >> wa2bfw at att.net
> > >>
> > >>
> > >>
> > >> _______________________________________________
> > >>
> > >>
> > >>
> > >> _______________________________________________
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> > >> TowerTalk at contesting.com
> > >> http://lists.contesting.com/mailman/listinfo/towertalk
> > >
> > >
> > >
> 
> 
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