RE: [BULK] - rant on "mil spec" wasRE: [BULK] - [TowerTalk]RG-11 Source?

[Jim Lux <jimlux@earthlink.net>]

At 11:42 AM 2/9/2005, Steve Katz wrote:
> Hi Jim,
>
> Good rant.
>
> I have mil-spec (MIL-C-17/6B imprinted) RG11/U on spools in my garage.  I'm
> trying to remember the mill, probably Carol or Times.  It's not very new,
> I've had it several years, probably mfd in 1990 or so; but, it's unused and
> has been stored in a dark, dry environment so is "new."


There you go.. it was probably made before they cancelled the spec.  It was 
the PVC jackets that were the problem apparently.


I also just learned that the real important difference between old MIL-C-17 
cables and new MIL-C-17"G" cables is that the new standard is much more 
sensitive to cables with periodic impedance bumps, because they require 
swept frequency measurements, as opposed to spot frequencies.  The way that 
cables are made apparently tends to result in periodic bumps (it's made on 
machinery with round pulleys, etc., and if there's a lump or a seam, it 
gets repeated every wheel rotation) which make a fairly narrow band problem 
(a resonance issue... like having a hundred section filter all tuned 
exactly the same).  The old test regime wouldn't necessarily hit those 
"dead" frequencies.

Another thing I learned is that there are NO Mil spec RG series cables 
anymore. Not just the PVC jacketed ones.  Now it's done with a QPL 
(Qualified Products List), and anything labeled as RG is, almost by 
definition, NOT mil spec (at least today..  that Korean War vintage spool 
of RG-8 all you TTers have sitting in the back yard, just in case, was made 
according to the spec at the time).


> Nothing special about the mil spec other than it's solid PE dielectric with
> real copper conductors, unlike a lot of commercial equivalents (which may
> actually be better in some ways) that are cellular PE, or have clad aluminum
> conductors and other stuff.  The mil-spec stuff is more mechanically robust
> by design and materials used; doesn't make it better for our purposes, and
> probably makes it a whole lot worse for CATV use.  For CATV, the quad
> shielded RG6 the cable companies use blows away RG11/U in just about every
> respect, including cost.
>
> That's why when I heard the application, I recommended against using RG11/U.
> The "thick net" cables used commercially nowadays are better in every way I
> can think of except mechanical strength.  The old solid poly stuff is
> stronger, in that you can drive a car over it and it still works.


There's some pretty tough armored stuff with foam dielectric 
around.  However it's very, very expensive.  Solid PE dielectric is 
probably a pretty good compromise between cost, ruggedness (at least laying 
flat), and so forth.


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