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Re: [TowerTalk] LMR and CNT

To: Tower Talk <towertalk@contesting.com>
Subject: Re: [TowerTalk] LMR and CNT
From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
Date: Wed, 26 Mar 2008 17:38:09 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Julio Peralta wrote:
> I can give you positive results. I'm using 600UF for preamp to antenna
> feed point connections including around the rotor on my VHF-UHF antenna
> systems and have had no problems in the 2 years it's been in service.
>   
I decided to go with a mix of LMR-600UF and Davis Bury Flex.
As I mentioned I'd not had the best of luck with the 400UF but it had 
lead a hard life so I want to get the 600 UF  a try.   I still plan on 
using Bury Flex to the tri-bander and 40 meter antennas with the 
exception of the half wave, center fed slopers which is CNT-240. It's 
been handeling a KW PEP out of the tuner with an SWR as high as near 3:1 
"at the antennas"

I ordered the 600UF and a *bunch* of poly rope in different sizes today 
and need to get a couple hundred feet of Bury Flex yet.

73

Roger (K8RI)
> Julio, W4HY
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of Michael Ryan
> Sent: Tuesday, March 25, 2008 5:08 PM
> To: 'Roger (K8RI)'; 'Rob Atkinson'
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] LMR and CNT
>
> 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
> 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
>
> -----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.
>
> 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. 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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