Dick, Thanks for the comments ref. Bury-Flex Tm vs. LMR-400 UF. I think
that answers Bob 's question.
Just to add, when I designed Bury-Flex Tm I used a medium density PE
(polyethylene). PE is highly resistive to rot, mildew, UF, various oils,
chem's and gasoline. It has a higher durometer than PVC (PVC can be had in
various formulas and is most often used for flexibility and relative low cost.
Only certain formulas of PVC are UV and plasticizer migration resistant.
DAVIS RF only uses the UV compounds of PVC for any type of cable that will be
used outdoors. But again, PE has even more qualities )
I have Bury- Flex Tm Buried directly in the ground, and laying on the
surface in my woods to my tower. It has been out there over 15 years. The
jacket is as shiny as new, really. I have all the critters here in MA and
they do not bother the PE outer jacket of Bury-Flex Tm.
We also have our various rotor cables that we sell extruded with a PE outer
jacket. We are only one of two dealers that I can find who uses PE. The
most common mfr. Of rotor cable is JSC Wire, they use a PVC outer jacket.
So, bottom line, PE is an excellent outer jacket material for resistance to
the above noted elements. I have not tested shelf life, or outdoor or
buried life, because it has been around 15 years so far that we have had
Bury-Flex Tm out there, and less years for our rotor cables, since we converted
to PE. But clearly, based on my experience and insight as a cable design
engineer, I'd depend on PE jacketing to be "out there" or on the shelf for at
least 30 years.
Our rotor cable with PE, as well as Bury-Flex Tm, and others, are available
from many ham dealers including HRO, Universal Radio, Texas Towers and others.
Any questions, feel free. Need ROPE of all types / sizes , at LOW prices,
made in USA?? DavisRopeAndCable.com (this is a totally separate company,
staff and location than DAVIS RF... please contact me for either company)
73, Steve, K1PEK Steve Davis, DAVIS RF Co. and DavisRopeAndCable.com
On 11/13/19, 12:50 PM, "Dick Green RLG Analytics" <dick@rlganalytics.com>
wrote:
I've had long outdoor runs of Buryflex, both direct-buried and in the air,
for more than 15 years -- probably close to 20 years -- with no degradation
problems.
Before going with Buryflex I used LMR400UF. I didn't use it long enough to
comment on degradation, but I did have significant problems with critters
chewing the cables, sometimes all the way through. I must have replaced the
100-foot run to my 4-square half a dozen times before replacing the LMR400UF
with BuryFlex. I haven't had any problems with critters since.
The other issue I had with LMR400UF was flexibility. I had a run going up
my 72' U.S. Tower rotating tubular tower, an application that requires
flexibility. I had a near-disaster where the coax migrated around the tower and
got hung up on the motor control cabinet, and determined that lack of
flexibility in the cable was partly responsible. I replaced the run with RG213,
which is pretty flexible but higher loss. A couple of years later I did some
tests with Buryflex and found that it's as flexible or more flexible than
RG213. Since the loss is considerably lower, I replaced the RG213 with Buryflex
and have had no problems in the 15-20 years since.
73, Dick WC1M
-----Original Message-----
From: Bob Shohet, KQ2M <kq2m@kq2m.com>
Sent: Tuesday, November 12, 2019 2:50 PM
To: Steve Davis | Davis RF <sdavis@davisrf.com>; towertalk@contesting.com
Subject: Re: [TowerTalk] LMR 400 UF issue and Low Loss cables in general
Re: TowerTalk Digest, Vol 203, Issue 15
Hi Steve,
Regarding Buryflex, what is the anticipated lifespan of Buryflex under
“normal” use cndx? How long can it be stored inside (prior to use) without
significant degradation?
Tnx & 73
Bob KQ2M
From: Steve Davis | Davis RF
Sent: Tuesday, November 12, 2019 1:20 PM
To: towertalk@contesting.com
Cc: wa6tla@icloud.com ; W4EF@dellroy.com
Subject: [TowerTalk] LMR 400 UF issue and Low Loss cables in general Re:
TowerTalk Digest, Vol 203, Issue 15
Hi Elliot
Mike, W4EF, hits it on the head ref. potential degradation of LMR 400 UF,
in outdoor environments vs. UV impact.
My firm, DAVIS RF Co., sells various RF cables, as well as control cables,
and provides government, military and numerous industries, with cable design
and solutions, not only in the RF spectrum. We are not just wholesalers, we
are cable design engineers fulfilling many custom needs. One cable I
designed, which many hams recognize, is Bury-Flex Tm, used also by Lockhead
Northrup and NASA ground stations.
In the past on T Talk, I have pointed out the issue with LMR-400 UF, and
suggested alternatives.
We sell a lot of Times LMR sizes, and in fairness to them, their cables in
general are superb. However, in order to max out flexibility of UF's, they
chose to use a TPE jacket (Thermoplastic elastomer).
This outer jacket material does not hold up well to UV, over the longer
term (depending on where in the world it is used). Times latest specs have
deleted ref. to the potential life of the cable. And W4EF'S experience, as
noted, confirms the problem.
So, what is the alternative??: Belden 9913F7, which has excellent
flexibility, and same attenuation specs (only slightly different at and over 2
GHz). And, 9913F7 is LESS expensive than 400 UF.
Why is it better vs. UV?? Because they use their own formulated "Belflex"
Tm outer jacket material. It is a highly flexible hybrid PVC. NOTE: do not
mix this cable up with Belden 9913, which at least in the ham market has had a
bad reputation. 9913F7 is a totally different build. And I highly recommend
it.
I will just add also that many customers come to me thinking they need to
run their entire length of a cable using a UF type, where there are
alternatives to that which results in our sale being less, but that also means
saving the customer his $$, which is what we want to do for our fellow hams ,
without sacrificing performance and application sense.
Lastly, we have very low prices on Low Loss cables, hardline, Andrew
Heliax and RFS Cablewave Heliax Tm equivalent. And we do the assemblies using
mfr. Certified installers. We provide our fellow hams with the same low
wholesale pricing as we do all other commercial customers. And we provide
free application consulting, unlike any other commercial or ham dealer that I
am aware of.
Contact me anytime with any questions. 73, Steve Davis, DAVIS RF Co.
On 11/12/19, 12:01 PM, "TowerTalk on behalf of
towertalk-request@contesting.com" <towertalk-bounces@contesting.com on behalf
of towertalk-request@contesting.com> wrote:
Today's Topics:
1. Re: Times Microwave LMR-400 UltraFlex Cable (Michael Tope)
----------------------------------------------------------------------
Message: 1
Date: Mon, 11 Nov 2019 20:56:47 -0800
From: Michael Tope <W4EF@dellroy.com>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Times Microwave LMR-400 UltraFlex Cable
Message-ID: <3199f5a5-9526-3649-f146-36c4a06d8d64@dellroy.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Are you planning on using the TM cable outdoors, Elliot? I had really
bad luck using LMR400UF in an outdoor application. While it was indeed
very flexible, the jacket essentially disintegrated in the Southern
California sun. Regular LMR400 by contrast holds up extremely well in
the SoCal sun. Apparently the UF variety uses a TPE (thermoplastic
elastomer) jacket whereas the regular LMR400 uses a PE (polyethylene)
jacket.
Unless Times improved the formulation of the UF jacket material, I
would
be cautious about using it outdoors without some additional protection
for the jacket (for a short rotor loop, a layer of 3M tape might do the
trick). For indoor service, it should be fine.
73, Mike W4EF
On 11/10/2019 12:28 PM, Elliott Lawrence via TowerTalk wrote:
> I?m looking for a source of Times Microwave LMR-400 UltraFlex cable
assemblies. I have found one company, Field Components in Florida, that
specifically states that they use this cable. Other suppliers, ABR, DX
Engineering etc have preassembled cables but do not specific Times Microwave.
Based on the pricing by those suppliers I doubt that the TM cable is used.
>
> Recommendations, suggestions etc would be appreciated.
>
> 73
> Elliott WA6TLA
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
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