At 04:34 PM 8/7/2002 -0500, Mark Beckwith wrote:
> >Before the grips were available, cable clamps
> >were used but the pressure caused the fibers
> >to cold flow so using cable clamps is NOT
> >factory approved.
>
>I already answered Sylvan on the side, but I would like to mention that
>AA6TT was 100% cable clamps on Philly and nothing there failed. Steve, what
>do you mean by "causing the fibers to cold flow"? I have built my station
>with stuff from AA6TT and I hope my towers don't fall over because I used
>cable clamps instead of grips.
>
>I know your prime directive, but mine is, to butcher Dave Leeson's immortal
>yet frequently misquoted wisdom, "experience has got to count for
>something." In this case, it worked okay for AA6TT so I am thinking it will
>work okay for me.
>
>Mark, N5OT
Depends on the formulation of the jacket and how it is applied. This
changed over the years. If you have old Philly like I do then potting
heads are the only option. Later versions allowed the use of cable
clamps but those were really not very satisfactory in my opinion.
Preforms (on the newer versions of Philly) are the right answer as
far as I am concerned.
But 1/2 inch Philly is uncommon in the amateur market so I wonder
if that is OD of the jacket or what. Maybe it is 3/8 EHS equivalent.
I have some and it came surplus from the broadcast industry. It
was old enough to require potting heads since it did not have a
jacket that would not slip along the kevlar.
I guess you can do what ever you want--it is only your life and
property at risk (and maybe the neighbors) but I would at least
find out the vintage of the Philly and confirm with the factory what
is the right way to terminate it--rather than relying on a lot
of opinions of people who may or may not have extensive experience
with the material. I have been using Philly since 1978 on government
and commercial installations. But I make sure I know what version
of the product I have and how to best terminate it.
Even on the stuff that was specified for cable clamps I never thought
it looked very good. Really deforms the jacket and makes it look
like the pressure points are all set to failure. I would much rather
use the preforms--if allowed--or potting heads--if not--and be safe.
John W0UN
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