On 11/21/2012 10:43 AM, Jim Thomson wrote:
That's a bit of over-generalization. Both RFS and Andrew make standard
and flexible versions of their cables. The construction is virtually
identical on comparable versions.
## since when did andrew start making 7/8” and 1.25” heliax with
corrugated center conductors ??
That andrew “flex” version of 1/2” heliax is nothing more than a corrugated
shield, making a sloppy fit
over the dielectric. All the andrew 7/8” + 1.25” heliax I have ever seen
always had a copper tube
in the center... = zero flex.
## I see andrew blathering on about the 1st to use corrugated aluminum for the
shield, but have yet to
see any andrew hekiax with an AL corrugated shield. Copper is 2-5% heavier
than steel and almost triple
the weight of aluminum. That RFS heliax with the corrugated AL shield + CU
corrugated center conductor
is the real deal.... super light,and super flexible, with no where near the
turning radius of standard andrew
offerings.
## that ‘superflex’ andrew 1/2” heliax is spec’d to be rolled and unrolled X many
times off a cable reel, that’s it.
It uses Cu clad solid AL for the center conductor. Nick the CU..and you are in
a real mess, esp if you ring it 360 degs.
That CU copper tube used on the andrew 7/8” and 1.25” heliax is no fun to work
with...pita. You can have it.
Later...... Jim VE7RF
Jim,
You seem to have a thing about Andrew. At this point it would help to
have actual model numbers and specs.
The traditional RFS "Heliax" is the LCF series, which is a virtual
carbon copy of Andrew LDF (or LDF is a carbon copy of LCF if you
prefer). These cables were, until recently, the workhorse of the
commercial segment. They are rugged and very easy to work with, at least
for anyone who has worked with Commscope Cell Reach smooth wall cable,
which is truly stiff as a board (yet has a minimum bending radius as
small as corrugated). It just takes a lot more force to bend it.
Andrew "Superflex" 1/2" is the FSJ4 cable, which has always had a spiral
shield and copper clad aluminum center conductor. There IS a spec for
number of bends, given as (20) minimum and (50) typical. I'm not sure
that any hardline is the right choice for a constant bending application
though.... FSJ4 has a minimum bend radius of 1.25".
The RFS Superflex "CellFlex SCF-12" also has a spiral shield and copper
clad aluminum center conductor, and is rated for 1.25" bending radius. I
can't find a spec for number of bends, but I can't see a world of
difference between the two cables, can you? Is there another RFS 1/2"
cable I'm not aware of?
Andrew VXL5 is Andrew's Flexible 7/8", and DOES have a corrugated center
conductor, weight .29lbs per ft, and bend radius of 5".
The RFS superfles 7/8" is UCF78, made similarly, weight of .302lbs/ft,
and bend radius of 5". See much difference there? Is there another RFS
7/8" superflex that I'm unaware of?
I don't think Andrew has made "flexible" cables in larger than 7/8",
although their air-line cables have corrugated center conductors.
I'm not a fan of aluminum shield cables, for precisely the reason you
gave for not liking CU center conductors (not sure I understand that).
Aluminum is much more fragile if nicked than copper. However, I can
assure you that there IS Andrew AL5 cable out there with corrugated
aluminum shield, but I'm not interested in it.
Anyway, that's about all I'll say on this, except that both Andrew and
RFS (and Eupen and Rosenberger for that matter) make high quality
corrugated cables that are well accepted. I used to have trouble with
RFS connectors meeting sweep specs at high frequencies (which RFS
engineers admitted to me were an issue) but that has been sorted out
with their later series.
73,
Steve K8LX
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