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Re: [TowerTalk] LMR-900-UF does it exist?

Subject: Re: [TowerTalk] LMR-900-UF does it exist?
From: "Roger (K8RI)" <>
Date: Mon, 05 Jul 2010 03:03:04 -0400
List-post: <">>

On 7/2/2010 7:57 PM, Jim Thomson wrote:
> Date: Fri, 02 Jul 2010 18:09:15 -0400
> From: "Roger (K8RI)"<>
> LMR-900-UF  does it exist?
> On 7/2/2010 1:59 PM, Jim Thomson wrote:
>> Does this LMR-900UF  actually exist??   If it does, it would be the real 
>> ticket.. and I have several applications
>> where it could easily be deployed.  The rigid LMR-900   and also LMR-1200DB  
>> is NO fun to work with at all.
> Nor are the UF versions when making a lot of connections.  The jacket is
> a rubber like material that does not adhere to the braid. This makes the
> use of regular strippers problematic at best and useless at worst. Well,
> actually I've had the jacket tear which meant cutting off the end and
> starting over.
> ##  well,  I have  T-Comm 600-UF.. which is just the silver plated version of 
> 600-UF... and yes,   the
> TCOM-600-UF  also has the rubber jacket.    It's way more flexible than 
> 213...almost like spageti.
> Who cares whether the rubber jacket sticks to the braid ??
I do. The rubber like jacket tends to catch on things, or does not slide 
easily causing the jacket to move, stretch, bunch up, and even tear.
>    I only have experience with just one piece of this
> stuff.
> I am a fan of the LMR series cables, but I am not a fan of the UF
> versions. The jacket is not only difficult to work with, but has a
> relatively short life compared to the regular LMR cables or Davis
> BuryFlex(TM).  I had to replace all of the pigtails to the antennas in
> the big array after less than 8 years.
> ##OK. this has me concerned!    What happens after 8 years ??
This is only my experience which makes one example anecdotal although I 
had 5 pigtails fail.
It appears to become more fragile and can tear more easily with age.  
All 5 pigtail jackets failed physically.

OTOH when we did the original installation, we ruptured the jacket on 2 
of the pigtails just pulling them into place over the edge of the tower top.
(45G flat plate) They didn't slide freely, bunched up and tore.
>   Does the UV kill the stuff ??
It appears to. It could be the weather as well and possibly temperature 
related. In the bright sun, black coax gets uncomfortably hot to hang onto.
I do know that when using the standard stripper it tends to grip the 
jacket which bunches up and then cuts unevenly or tears. It's far easier 
to prep using a good sharp box cutter and flush cutting side cutters 
that have a curved edge so it doesn't flatten the cable or center conductor.
>     How do u know it's
> trashed ?
Physical failure of the jacket and then water ingress.
>     Does the attenuation go way up/arc, watter ingress/etc ?
I've never noted the attenuation to go way up as the UF pieces were less 
than 10% of the total length.
> If that's the case, then the uF version is better suited for indoors.
That's what I hope as I now have over 200 feet of LMR-600UF in conduit 
and another 200' coil in the shop.  Although if I mount the 144 and 440 
arrays on a cross boom setting on a ring rotator I may use it there.  
Actually the only place we couldn't reach without lowering the antenna 
would be the 6-meter antenna. There the antenna has to come off the mast 
as it's a good 12 to 15 feet to the fitting on the driven element.
>     Dunno why then, they didn't just use the
> regular jacket..
I think the jacket is one of the reasons the stuff is so flexible. I've 
only see one other example of RG8 size and larger that was more 
flexible. I don't know who made it or where it came from, other than one 
of the locals picked up a *bunch* of the stuff years ago. The jacket is 
a silver color, it's soft, but more slippery than the UF cables. It had 
a smell similar to amines or hot plastic. IOW it stunk, but it sure was 
flexible.  With age and exposure to the sun that stuff darkened and had 
a deposit build up on the outside that looked like a big long scab with 
cracks in it for lack of a better description. The surface would get 
kind of crusty, but it would become soft enough to dig into with your 
fingernails. Twas nasty, disgusting stuff and probably unhealthy to 
handle<:-)).  I still have some short pieces that have not been outside. 
For flexibility it reminds me of large RG8X. It seems like it was called 
something like extra flex, but that was probably 30 years ago and there 
are no markings on the few short pieces (3 or 4) I have left.
> like on 600-DB, etc.    I think the reason the 600-UF is WAY more flexible 
> than  213 is...
> in large part, cuz of the rubber jacket on the UF cables.
> ## The plan was to run LMR-1200DB  from basement to base of tower, then into 
> the Hoffi lightning
> protector, [bulk head type], then into the Tcom-600UF... which goes up the 
> side of the crank up tower, and
> terminates into the remote switch box on the mast.   Then 393 teflon coax for 
> the pigtails to each yagi.
> ## I need something flexible for the single run of coax up the side of the 
> tower, something with low loss, and handles
> YC-156 power.  My only other option is 393 up the side of the tower...and the 
> loss on that stuff is no better than 213-U.
The UF cables 900 and 1200 would be the most flexible for the size, but 
I'd be afraid of that jacket if the cable has to slide on anything.  If 
the jacket were protected in the areas of the support arms, 
say...sleeved, or reinforced/protected with heat shrink tubing the rest 
hanging freely might do OK.
If you want to use something that large, and I can understand why, I'd 
call or e-mail Times Wire and and ask for their input for such an 
installation.   Even in clear weather you don't get the UV exposure we 
do unless you are at 7 or 8 thousand feet in the mountains.  I think the 
UV doubles for every 3000 feet, but that's just a recollection which may 
not be very accurate.
> ## Plan B is... I could try the TCOM-600UF since I already have it.. and if 
> it's a problem down the road, then replace it with 393.
If you already have it that would be my choice. You might as well get as 
much use out of it as you can and your experience might prove to be 
better than mine.
With a crank up I'd not be nearly so concerned as I am with a guyed, 
100' 45G and 28' pigtails that go well out of reach which makes 
replacing them substantial work. I have to pull the rotator, lower the 
DOM mast, loosen the boom to mast clamp on the mast for the bottom 
antenna, continue lowering the mast until the next antenna sets on the 
bottom one, loosen that mast clamp in the same manner and then continue 
lowering the mast until I can reach the top antennas. Remove the 
pigtails, replace them with new ones and then reverse the procedure with 
the mast.  At my age I pretty much now have to hire that kind of work 
although I did make a relatively easy climb today which surprised me.
> In any event, I will use 393  from remote switch box on mast, to each of the 
> 4 x ants.   The last thing I need is a problem with
> pigtails, esp when some of the DE's  are way out on the booms.  I will also 
> use the dow-corning  DC-4/5 silicon grease  on the
> 7-16 DIN's.    Then vapor wrap/88 tape/heatshrink etc.
Using that procedure with UHF and Ns (before I knew better) I flooded 
the connector, used a layer of flooded heat shrink, thorough layers of 
33 tape, and then two coats of liquid electrical tape.  I removed a 
couple of those that had been up nearly 10 years and the connectors 
looked like new.  OTOH, I had two, two-way power dividers (one for 144 
and one for 440) that lost their seals.  They apparently had at least 
several inches of water standing in them one or more times.  They were 
dry when I took them apart.  The water had gone through the coax 
connector  and then into the coax on the other side (the connectors were 
not flooded).  Fortunately each had a substantial drip loop. The coax 
exited at 90 degrees to the mast and then made a 270 degree curve up and 
then on down the mast. Only the brad in the connectors showed any sign 
of deterioration, but it was substantial at those points.  I should 
point out that the LMR 400UF at those points was still in good shape.  
The only bad spots were where it coiled around the mast and laid on the 
tower top plate allowing the mast to rotate.  Still, in this area there 
was very little physical movement in the coax.  It made 3 complete turns 
around the mast with the mast capable of only 1 1/2 turns.
> ##  When I first saw that UF  rubber jacket,  I wondered  if it was any good 
> for UV.  If the  Tcom-UF bombs out on me for any reason,
> it's real easy to replace, with tower nested..since the remote swictch box on 
> mast will  25-26' above the grnd.
Good luck. That sure beats what I have at the 100' plus level. OTOH when 
they go back up there will only be two antennas on top of the 445G. A 
40M3-125 and the 7L C3i 6-meter Yagi.  The Force 12 tribander and 
possibly a WARC 7 will go on the little 50' 25G on the West end of the 
shop where they should be much easier to access.
> later.... Jim  VE7RF
>> If it doesn't exist, then they should consider making such a product.    
>> Does anybody know ?
> 73
> Roger (K8RI)
>> Later... Jim  VE7RF
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