[TowerTalk] LMR degradation

[Patrick Greenlee]

What about putting something over the rotation loop coax? How about the 
corrugated black plastic wire loom covering?  Or better, maybe a cloth cover 
made from sun resistant awning material.  Even I could sew up something as 
simple as that, just one long seam.  Alternatively you could just loosely 
wrap the cloth around the coax and secure with an adhesive, maybe securing 
with string around it in several places to hold it together while the 
adhesive is setting/curing.  Maybe contact cement and no wait after putting 
it together. worried about longevity?  Put on two or more independent 
layers. The second layer won't begin to degrade from the UV until the first 
layer fails. Ditto the 2nd and 3rd.  Good sun resistant awning material last 
for years in the sun and weather.

There is flexible corrugated looking spiral wrapped aluminum conduit that 
flexes very easily, enough to handle the flexure required of a properly 
constructed loop.  A bonus would be that the aluminum doesn't transmit much 
UV through to the coax jacket.  The spiral wrap flexible aluminum conduit is 
not water proof (don't get the type with the plastic coating as it is much 
stiffer and will hold water.) The Flexible aluminum conduit will drain and 
not retain water.

Comments?

P.S.  The 40 ft tall tower with 14 ft plus leg separation disassembly 
project has been on hold while I assist an older ham get up an antenna mast 
to get his antenna up almost 40 ft.  Also the series of sprinkles and cold 
winds have been discouraging.  I did manage to make the trip to the site 
twice, once to clear brush and 30 years growth of trees with trunks and 
branches intertwined in the tower's X braces and a second trip with a 
tractor to push the brush and downed trees out of the way so I can get in 
with my trailers, tractor, and truck.  As promised, I'll have pix when this 
project moves forward.  I have two other towers on the ground waiting for 
bases and to be put up.  I am anxious to get my hex beam up so I might 
install one of these before I take the BIG ONE down.

73

Patrick AF5CK

-----Original Message----- 
From: Cqtestk4xs at aol.com
Sent: Wednesday, March 27, 2013 7:57 AM
To: TOWERTALK at contesting.com
Subject: Re: [TowerTalk] LMR degradation

Like I said in my post I've been using regular LMR 400 for years on many
antennas.  Never had a failure if you leave a good sized loop.

Bill K4XS


In a message dated 3/27/2013 2:37:48 A.M. Coordinated Universal Time,
gary_mayfield at hotmail.com writes:

What are you supposed to put around the rotor  then?

73,
Joe kk0sd



> From: Cqtestk4xs at aol.com
> Date:  Tue, 26 Mar 2013 11:42:22 -0400
> To: TOWERTALK at contesting.com
>  Subject: Re: [TowerTalk] LMR degradation
>
> Back in the early  2000s I had a long conversation with the guys at
Times.
> The ultra  flex on many of my jumpers had cracked after only a couple of
> years  in the FL sun. His response was the ultraflex was not supposed to
be
>  used outside.
>
> He offered to replace the stuff with regular  400 but I never took him up
> on it.
>
> I use the regular  LMR 400 on all my jumpers and have had zero problems.
>
> Bill  K4XS
>
>
> In a message dated 3/26/2013 1:25:47 P.M.  Coordinated Universal Time,
> k8ri at rogerhalstead.com writes:
>
> On 3/25/2013 2:31 AM, Jim Brown wrote:
> > On 3/24/2013 9:42  PM, Jim Hoge wrote:
> >> Today I discovered that I have had  environmental ingress beneath the
> >> outer jacket of some ~8  year old LMR-400.
> >
> > In the latest (I think) version of  his excellent Managing Interstation
> > Interference," W2VJN notes  that he observed degradation in the measured
> > performance of stubs  made of LMR400 that had been sitting in his garage
> > for a bit less  than a decade. He seemed to think it was due todegraded
> > contact  between the foil and braid shields. This was written several
> >  years ago. He may have more to say about it by now.
>
> We've  known for years the UF versions of the LMR cables deteriorate out
> in  the elements. It follows that they'd possibly do so with age as well.
>
> I found that the braid had almost disentegrated in some pieces of
> LMR400UF where the jacket "appeared" to syill be in good shape. I
> thought perhaps the jacket had become porous, but perhaps not?I  wonder
> which LMR400 he's talking about.
>
> 73
>
> Roger (K8RI)
>
>
> >
> > 73, Jim  K9YC
> > _______________________________________________
>  >
> >
> >
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