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[Towertalk] Coax opinions

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Subject: [Towertalk] Coax opinions
From: (W0UN--John Brosnahan)
Date: Wed, 07 Aug 2002 19:31:56 -0500
>  I know the Belden is Mil spec and the others aren't, but the
>composition and loss seem to be the same.


Others may or may not be mil spec--just depends.   And to
what mil spec.   C17D or C17F or whatever.

Belden used to be (don't know if it still is) calling their RG-8
RG-213.  Let me explain.  RG-8 has a 7 strand center conductor
of a particular gauge wire (#something--forget at the moment--
whatever makes it look like 52 ohms).  RG-213 is SUPPOSED
to have a 7 strand of a decimal 3 digit number--but the tolerances
for the wire put the # wire within spec.   So for a long time
Belden was making the same stuff for Mil spec RG-213 and
RG-8.   As did other manufacturers--who claimed they just
made it the way it was shown in the Belden catalog.

Times wire was an exception as were a few other 2nd tier
manufacturers.  I have used 100s of thousands of feet of
Stand Wire and Cable RG-213 out of Los Angeles and had
very good luck with it.   And it is MUCH cheaper than Belden.
Been a couple of years since I have bought any--but in
1000 ft reels (1 or 2) it was only about 32 or 33 cents per ft.
Probably more expensive now--but probably not by much.

My point is that Belden is not the gold standard that it tries
to be by pricing itself at 90 cents per ft.

The key is PVC IIA non-contaminating jacket.   One thing
I can say about Belden over a lot of other vendors (except Times)
is that they hold their jacket OD tolerances much better than most.
I have a pneumatic coax measurer/cutter/stripper and Belden
always runs smoothly.   Standard has also been very good--
but some of the other 2nd tier guys stuff won't even go through
the guides at times.

One thing I always do is to run every single foot of cable through
my hands.  They are very sensitive to anomolies and I can
detect a spice in the braid very easily.   A lot of the companies
splice the braid (if need be) by just overlapping the two braids
by a couple of inches.   Don't recall ever catching Belden or
Times doing that.   And I am pretty sure that I have not seen
any (but not as sure) of the Standard stuff.

There are other issues of importance--especially for me with the
automatic stripper.   Mainly at what temp the PVC jacket was
added.  If it was too HOT during manufacturing then it melts into
the braid and it is very difficult to strip with the machine.   If it is
too cold then it slides very easily over the braid and makes me
wonder what it is doing in a vertical run.   Is the clamping just
holding the jacket and braid and is the dielectric and center
conductor slipping down inside?

Anyway--all issues in addition to the 50 vs 52 ohm deal.  Joel
at RF Connection has some lower cost LMR400 that I used
in Rhode Island and it seemed pretty darn good and much
cheaper.   Of course it is foam and the VF can vary a lot
more with foam--depending on the percentage of air bubbles
in the run.  They also have some bigger stuff that is pretty
cheap (compared to Belden) and you might want to investigate
that.   We used a direct burial version of LMR600 for the
main feedlines.

BTW   I have also seen the shield so discolored that it was
hard to get it to take solder.   Not sure what causes this--too
hot of jacket at application or what.  Anyway it looks oxidized
and does not take solder.   Of course this is from some low-
end vendor stuff that was provided to me by the government
who did the actual purchasing.

73--John   W0UN

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