[TowerTalk] LMR-600: Crimp or Clamp Connectors?

[Roger (K8RI) on TT]

I use mainly LMR 600 and crimp connectors.  Good crimpers are not 
terribly expensive, although not cheap.
Yes, the Ultra Flex (UF) versions definitely do have a fragile and 
easily abraded  rubber like jacket.   I've had LMR400UF fail in 6 years 
where it rubbed on the tower top plate.

Typically I use crimp connectors on everything from 8X to LMR600, but 
beware. UHF connectors tend to be fragile, and/or very expensive.

Rotator loops?    You can use regular LMR 400 and 600 in rotator loops, 
I've done it and it worked well, BUT to do so takes a bit of work.  You 
need to fabricate a shelf or plate to support  a 3 turn loop with a 
diameter of at least 18 inches.  It acts like a coil spring.  Start with 
the rotator at mid rotation, so a half turn one way tightens the coil 
and a half turn the other way, loosens the coil.  At 18" diameter there 
is very little bending with a half turn in a 3 turn coil

The UF versions are the most flexible cables I've used. They are even 
more flexible than BuryFlex(TM), but no where nearly as rugged.  If 
money and replacing the cable every 5 to 6 years is not a problem, then 
I'd use LMR600UF, BUT  because of the center conductor migration in 
vertical runs, the weight, and cable life, I'd choose BuryFlex(TM) for 
crank ups  and rotator loops.

  I have strong reservations about the use to which a crank up would put 
on the UF versions.  Even with BuryFlex I'd put a 2 turn loop at the top 
arm with a at least a 12" diameter to reduce strain on the center 
conductor and conductor migration, or use a snug fitting EMT sweep 90. 
(Be sure to eliminate sharp edges.) I'd prefer a 450, but that takes 
someone really good at bending EMT.

With a regular tower, I'd put a 1 turn loop of 16 to 18" in diameter 
every 50 feet  (laid flat against and taped to the tower face) To 
prevent, or minimize center conductor migration.

A bracket with a thoroughly waterproofed bulkhead connector at the end 
of the rotator loop would be a good place to ground the coax shield at 
the top of the tower.

73

Roger (K8RI)

On 6/4/2015 7:28 AM, Richard Thorne wrote:
> I'm going to replace all of the RG213 coax on my current tower with 
> LMR-600.  I've been researching connectors.
>
> Looks like there are two varieties, crimp and clamp connectors. After 
> watching a few you tube videos of the installation process of both, 
> I'm leaning towards the crimp type.  It does require a good crimp 
> tool, but it looks a little more robust than the clamp variety.
>
> Any opinions out there if one is better than the other?
>
> Thanks
>
> Rich - N5ZC
>
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-- 

73

Roger (K8RI)


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