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Re: [TowerTalk] LMR and CNT

To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] LMR and CNT
From: "Mel Whitten" <mel@melwhitten.com>
Date: Tue, 25 Mar 2008 21:29:07 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
I believe the "life" of UF is about 5 years if your in Florida
or Arizona with its higher UV.... otherwise TM says:

LMR 400UF
Weatherability:  LMR-400-UF cables are designed

for outdoor exposure and have a life expectancy in excess

of 10 years.

LMR 400

Weatherability:  LMR-400 cables designed for

outdoor exposure incorporate the best materials for UV

resistance and have life expectancy in excess of 20 years.

All the specs are here in pdf

>http://www.timesmicrowave.com/wireless/<

Mel, K0PFX

----- Original Message ----- 
From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
To: "Michael Ryan" <mryan001@tampabay.rr.com>
Cc: "'Rob Atkinson'" <ranchorobbo@gmail.com>; <towertalk@contesting.com>
Sent: Tuesday, March 25, 2008 4:42 PM
Subject: Re: [TowerTalk] LMR and CNT


> Michael Ryan wrote:
>> Interesting comments on the cables. I was under the impression that 
>> LMR-600
>> UF ( ultra flex ) was plenty flexible to use up the tower including the
>> rotator loop area. It looks and feels heavy but does indeed appear to be
>>
> My only complaint  about LMR-400 UF is the jacket which appears to be a
> rubber like material with poor resistance to abrasion and has not held
> up well.  I had to replace it once when the pins in the mast sheared and
> let the antennas windmill.  This pulled the cable tight over the edge of
> the tower top plate and stripped the jacket right off.  It came of like
> a rubber tube. Of course that may have ruined any cable from either
> kinking (the 400 didn't kink), or abrading a strip off the jacket for
> other cables.  The cable is plenty flexible, and I was able to use the
> regular connectors on it. Unfortunately after 6 years it's  time to be
> replaced.
>> much more flexible than 1/2 heliax which one would never use for a 
>> rotator
>> loop. Has anyone has negative results with the 600Uf in such an 
>> application
>> as I have suggested I wonder?  - Mike
>>
> The only reason I've chosen to go with the Davis "Bury Flex" is its
> reputation for resistance to abrasion.  IOW the stuff is rugged.
> Otherwise I'd prefer the LMR 600 UF, but that is over twice the price of
> the Davis cable and I'm a bit cautious after the LMR-400UF.  There are
> pigtails for 144, 440, and 50 MHz.  Probably a second 144 as  I want to
> add a horizontally polarized yagi.  The Tribander has a short pigtail
> and doesn't gain anything worth while using the larger coax so that
> would certainly remain the Davis Bury Flex.  There is also the
> possibility of a Wi max antenna going "up top."
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Roger (K8RI)
>> Sent: Tuesday, March 25, 2008 4:27 PM
>> To: Rob Atkinson
>> Cc: towertalk@contesting.com
>> Subject: Re: [TowerTalk] LMR and CNT
>>
>> Rob Atkinson wrote:
>>
>>> My advice--if you are considering going with LMR or CNT and the cost of 
>>> a
>>> run of one of them, you may as well spend a bit more and go with 1/2 
>>> inch
>>> heliax LDF4-50 and get it over with.   There's always this debate about
>>>
>> how
>>
>>> on HF the reduced loss isn't enough to make it worth it but that's not 
>>> the
>>> point--the stuff is almost indestructible with its jacket and solid 
>>> shield
>>> it would probably jam a wood chipper and you'd be done with feedline
>>>
>>>
>> We all have different viewpoints.  I replaced LDF4-50 with LR-600. For
>> my use (laying on the ground from the shop to the tower 6-pack and then
>> up the tower) I found the Andrew to be more fragile, (easily dented,
>> easily kinked, and has a much larger minimum bend radius than even
>> LMR-600). So once I finish all runs up the tower will be LMR-600 and the
>> LMR-400 currently on the ground will be replaced with 600 in underground
>> conduit.  The LMR-600 on the ground will also go into the conduit.
>>
>> I use CNT240 and LMR-400 runs from the antenna switches to the slopers.
>> As I use all crimp connectors I never noticed any problem, but both
>> cables are listed as tined copper braid over Al foil shields from the
>> suppliers.  Neither CNT240 or the LMR cables are what you would call
>> flexible when compared to  the RG8X family.
>
> LMR or CNT 240 can be a royal pain in the backside to strip without 
> scoreing the braid, so you use a properly adjusted stripper for that one 
> or a lot of care. Scoring the jacket and then breaking it  works very 
> well. The pigtails at the top of the tower are currently LMR-400 ultraflex 
> which has not proven to be all that durable. The pigtails (with integral 
> rotator loops) will be
> replaced with Davis bury flex.
>
>>
>>> forever.   If you don't care about that go with 213.   I have never 
>>> really
>>> understood why anyone bothers with the times microwave coax.  All that
>>>
>>>
>> It's good, it has a short bend radius and it's relatively inexpensive
>> and I find it to be very robust.  The only cables that have given me
>> problems have been the Belden and the ultraflex versions of LMR-400.
>> I've had 3 runs of LMR 400 laying on the ground between the shop and
>> tower since last fall.  They've been walked on, run over by the yard
>> tractor, tripped over and show no damage.  Normally they'd not be on the
>> ground but some of this work started after the ground got kinda hard. IE
>> frozen last fall.
>>
>> 73
>>
>> Roger (K8RI)
>>
>>> expense for a feedline that is not all that robust.
>>>
>>> 73
>>>
>>> rob / k5uj
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>>
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