Re: Rotating LMR400, many will say it's fine to rotate and "it works fine
for me." Although it may work fine, I've noted visible deterioration in the
center conductor after only 50 or so sample rotations using a 12" radius
loop. Of course, you have to cut open the cable to look for this -- it's
not visible from outside, and hairline cracks in the aluminum (copperclad)
center conductor may not actually harm performance. It seems the point of
major stress would be the lower support point where the rotator loop is
supported to the tower leg, standoff arm, mast, or whatever will keep it
from falling to the ground. If that point is the sole support point for
30-40 pounds of free-falling cable and is rigidly bound to a hard surface
(steel tubing), and the loop above it moves freely with rotation or the
wind, that is quite a stress point.
For such an application I always use something with a stranded copper center
conductor, rather than a single clad aluminum center conductor like LMR400
has.
Since you've already got the cable and it's already buried, you might
consider making only "rotor loops" (the portion of coax that goes from the
beam feedpoint down, around the rotor) out of something more flexible and
then splicing to the LMR400 below the rotor.
WB2WIK/6
"If everything seems under control, you're just not going fast enough." -
Mario Andretti
> -----Original Message-----
> From: KB2HUK@aol.com [SMTP:KB2HUK@aol.com]
> Sent: Friday, October 18, 2002 11:02 AM
> To: towertalk@contesting.com
> Subject: [Towertalk] lmr 400 question
>
> <PRE>HI everyone , I have a question about lmr 400 I have 3 runs of this
> cable
> ready to be run up my tower next spring the cable is already buried. is
> the
> lmr 400 ok to connect to a yagi or other antenna on a rotating mast ? is
> it
> flexable enough? I am asking about a standard hook up . thanks John
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