Bill,
I've used Bury-Flex and also 9913F7, as well as other clones like IEWC
9096-IIA and Cable XPerts CXP1318FX. These are all quite similar.
I can't tell a lot of difference between them; however to rate a foam
dielectric cable having a stranded center conductor up to 4 GHz takes a lot
of intestinal fortitude, since stranded conductor cables start falling off
much above 1 GHz, especially when the dielectric containing them is as soft
and spongy as cellular PE. LMR400 and cables having foam dielectrics but
with a solid center conductor are much more likely to maintain
characteristics at such high frequencies; at 4 GHz rarely does anyone use
stranded conductor cables for much of anything, much less transmission lines
where attenuation is an important parameter.
While Belden manufactures its own cables and these other brands don't, most
of the American-made coax of this construction comes from a small handful of
mills who private label for anyone buying sufficient quantities; in my
experience, "sufficient quantities" isn't very much. I've been offered
private label service for quantities as small as 5000 feet (five x 1000'
spools). Unless and until materials change to ones less toxic when melted
or burned, most of this manufacturing seems to be occurring in older cities
east of the Mississippi having less stringent EPA requirements than my home
state (California), where making anything from PVC is difficult (toxic fumes
at high temperatures).
The cables having a 100% foil shield (as the primary outer conductor, with a
secondary conductor made of braid for clamping/soldering) shouldn't
contaminate no matter what the jacket does, since the foil stops migration.
If the Belden product costs only $.20/foot more and seems better, I'd
certainly use it. Small investment spread over the operating life of the
cable, which is probably ten years. I haven't swept any of the 9913F7 up to
4 GHz, but that would be interesting, especially if done after bending it...
-WB2WIK/6
"Success is the ability to go from failure to failure with no loss of
enthusiasm." -Winston Churchill
> -----Original Message-----
> From: Bill VanAlstyne [SMTP:w5wvo@cybermesa.net]
> Sent: Tuesday, April 27, 2004 1:44 PM
> To: towertalk@contesting.com
> Subject: [BULK] - Re: [TowerTalk] Using Belden 9913 on a crankup?
>
>
>
> I looked up this Bury-Flex stuff on the above-stated website -- they call
> it
> "RF-9914F" -- and compared its specifications to those of Belden 9913F7
> (the
> "flexible" version of 9913). I'm currently using Belden 9913F7 on all my
> antennas. As far as I can see, "Bury-Flex" and Belden 9913F7 are virtually
> identical in concept and construction: .405" jacket, .108" stranded center
> conductor, 100% coverage foil tape shield, 95% coverage tinned copper
> braid
> shield. Some comparative notes:
>
> a) Belden uses their own proprietary direct-burial jacket material
> (Belflex(R)
> PVC blend) on 9913F7, while Bury-Flex claims only "PE" (polyethylene) as
> the
> jacket material.
>
> b) The capacitance per foot and velocity factor specs vary slightly,
> probably
> due to a different formulation of the dielectric material.
>
> c) Up to about 200 MHz, the claimed losses per 100 ft are essentially
> identical -- but above that, the Belden 9913F7 starts looking better and
> better
> compared with the Bury-Flex, which isn't even spec'ed above 1 GHz. (Belden
> 9913F7 is spec'ed up to 4 GHz.) At 1 GHz, for example, the Belden 9913F7
> is
> spec'ed at 4.6 dB / 100 ft, while the Bury-Flex is spec'ed at 5.3 dB / 100
> ft.
>
> So my theory is that "Bury-Flex" is a knock-off of Belden 9913F7, but uses
> a
> cheaper dielectric material, which accounts for its differences in
> velocity
> factor and capacitance (both dependent on dielectric constant), and for
> its
> increasingly poorer loss performance in the UHF range. While no specs are
> given
> for flexibility, the virtually identical construction of the two cables
> suggests
> that the flexibility should be about the same, also.
>
> The cost differential -- in small quantities, anyway -- is quite
> significant.
> 100 feet of Belden 9913F7 from AES costs $79.99, while the same quantity
> of
> Bury-Flex from Radioware costs only $59.50. It certainly looks like the
> Bury-Flex is the better "deal" if you're going to be using it at HF or low
> VHF
> frequencies (6M and 2M).
>
> Question is -- I don't see any data on where they get this stuff from, who
> makes
> it, etc. Do I really want to go with a no-name cable when I could pay a
> few
> dollars more and get Belden? I suppose it depends to some degree on how
> tight
> your finances are, but for me, I would feel more comfortable going with a
> cable
> whose manufacturer I know and trust.
>
> I'd be interested in hearing any other data, opinions, testimonials,
> flames,
> etc. Has anyone tested Bury-Flex, both when it's new and after it's been
> installed for a while, to see how good it really is compared to Belden?
>
> Bill / W5WVO
>
>
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