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Re: [TowerTalk] LMR400 vs BuryFlex

To: Rudy Bakalov <>
Subject: Re: [TowerTalk] LMR400 vs BuryFlex
From: "Roger (K8RI)" <>
Date: Wed, 28 May 2008 23:32:01 -0400
List-post: <">>
Rudy Bakalov wrote:
> Hello all,
>   As I am getting closer to having the new tower and antennas go up, 
> questions that I have never considered in the past keep on coming up.  One of 
> them is the choice of coax.
>   As the title suggests, I am trying to decide between LMR400 and BuryFlex.  
> I estimate that I will need a total of 1000' to connect all 4 beams, the 
> phasing lines, 2 cables to the shack, etc.  The max distance between an 
> antenna and the shack will be less than 300' (or 0.3db loss).
>   I like the LMR400 option due to its lower cale loss and cost.  However, I 
> don't understand the practical impact of the fact that LMR400 is NOT 
> non-contaminating- is there going to be any impact from bundling cables, 
> attaching them to the tower legs, etc.?
Probably not. I've never noticed any adverse effects from taping the 
coax (I have 5 runs up the tower) to a tower leg.
>   The cables will go in a PVC conduit between the tower and the shack.
As do mine.
>   I do recognize the difference in flexibility (and its applicability to 
> rotating antennas) and my solution is to have a 10' BuryFlex attached to each 
> yagi, followed by whatever length of LMR400. I have to install Polyphaser 
> coax in-line protectors anyway and I will install them between the 10' 
> BuryFlex and LMR400 sections.
I'm replacing my runs with LMR-600 and using LMR-600UF for rotator 
loops. As to the Polyphasers,  I'd never put one at the top  of the 
tower or at the antenna. Remember they are sacrificial devices and when 
one does its job it may fail and need to be replaced.  The bottom end of 
my rotator loops go to bulkhead connectors mounted in 1 1/4 X 1/8" 
Aluminum angle fastened to the tower legs using saddle clamps.  The coax 
shield is again grounded at the base of the tower before it goes into 
the conduit.  All polyphasers are mounted at a grounded bulkhead at the 
entrance to the house. has some earlier 
photos of the installation.

However I think the Davis Buryflex is much more rugged than the LMR UF 
versions and would not hesitate to use it instead of them for the 
LMR-400 rotator loops.  I think you will find Buryflex is easier to 
handle (pull through conduit) than the LMR-400 but I think both are good 
cables.  So far I've had no problems with the LMR 400 except some 
rotator loops made from LMR-400UF, but that really wasn't the fault of 
the cables although Buryflex may have withstood the abuse a bit better.  
The rotator limits failed and the big array wound the rotator loops 
tight around the top of the tower and over the edge of the top plate.  
Where they skidded over the edge of the top plate it peeled the jacket 
right off.  Using tape and "heat shrink" I repaired them instead of 
replacing them which would have easily have been a full day's job.  Now, 
as everything is coming down they are getting replaced with the 
LMR-600UF IF I stay with the present antenna set up.  If I go with the 
4L "shorty fourty" then most likely the UHF/VHF antennas up top will not 
go back up and I'll have less need for the LMR-600UF.
>   Any thoughts?  The difference in cost is about $150 at 1000'
I think either will work fine, but even using Buryflex all the way I'd 
still put in bulkhead connectors to ground the shield at the top and 
bottom of the tower.  My runs are about 230 feet from rigs to the 
antennas up top.  However I'm using a "six pack" at the base of the 
tower for HF which eliminates 4 100' runs of LMR-400 and lets me use 
those antennas from either the den or shop, or rater it will once I'm 
finished with the overhaul. <:-))  (It's a big page with 
lots of photos)


Roger (K8RI - ARRL Life member)
N833R (World's oldest Debonair)
>   Thanks,
>   Rudy N2WQ
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