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

[Jim Lux <jimlux@earthlink.net>]

At 09:19 AM 2/9/2005, Steve Katz wrote:

> Tower Talkians,
>
> Anyone have a good source for quality RG-11?
>
> ::I have mil-spec RG11/U on spools.  How much do you need?

I don't want to beat up on Steve here, but he triggered an area near and 
dear to my everyday work.
Just a quibble here about the term mil-spec... (a similar phenomenon occurs 
with high rel electronic parts, except there, it's with reference to 883B, 
Class S, etc.)

There's nothing special about mil-spec stuff. It just means that someone, 
somewhere who had to buy something for the government wrote a spec, got it 
approved, etc. For instance, MIL-P-43988 is the 10 page mil-spec for toilet 
tissue in MRE-Packets (actually, it's been superseded by ASTM-D3905-1993, 
Toilet Tissue, Industrial). We also, of course, have to ask the question, 
"Whose military?"

Of course, the military tends to buy things that can operate in harsh 
environments, so if you've picked the "right" mil-spec that might imply a 
better quality (or more appropriate) widget.  However, for some things, you 
might not want the mil-spec product: perhaps non-mil-spec Charmin might 
provide a better toilet tissue experience than ASTM D3905 compliant 
stuff?).  A good example is MIL-STD-810, which defines a variety of 
environments for equipment; Be aware that some of those environments are 
pretty benign, so claiming "meets MIL-STD-810" for your radio might not be 
all that impressive, however, some of those environments are pretty abusive

One aspect of using industry standard designations (and that's 
fundamentally what a mil-spec is) is that there is the (legally 
enforceable) assumption that the product being sold has been tested or 
verified to comply with the spec. Here, we get into such fuzziness as 
"designed to meet".   The problem comes in about whether you can really 
sell something as complying with a specification that no longer exists 
(officially).  I couldn't do an electrical design for a client and claim 
it's "code compliant" if it met the 1981 NEC.

And this is where the problem lies. There is no such thing as "mil-spec" 
RG-11 any more... Just like there's no such thing as mil spec RG-8, RG-213, 
etc. All the polyethylene insulated cables were purged 10 or more years ago.

Back in August 1993:
"
CABLES, RADIO FREQUENCY, FLEXIBLE COAXIAL, 75 OHMS,M17/6-RG11, UNARMORED, 
M17/6-RG12, ARMORED
..
MIL-C-17/6B is inactive for new design. For new designs use specification, 
MIL-C-17/181B, Cables, Radio Frequency, Flexible, Coaxial, 75 Ohms, 
M17/181-00001 Unarmored, M17/181-00002 Armored.

The Qualified Products List (QPL) associated with this inactive for new 
design specification will be maintained until acquisition of the product is 
no longer required whereupon the specification and the QPL will be canceled.

"

Not to say that you couldn't legitimately claim that you've got cable made 
to a particular obsolete spec.  Or, you could say, I'm selling coax with 
the following characteristics, and then have your own mfr spec that happens 
to copy the parts of MIL-C-17/xxx needed.

And, you might use the (obsolete) RG number as a shorthand to illustrate 
the type of cable. i.e. "RG-8 type cable"  This is what Belden does... 
their cables are all made to Belden specs, and have specific Belden part 
#s, and they get identified as "Type 11 cable", meaning, looks a lot like 
what you used to buy as RG11, in terms of impedance and physical 
dimensions, but not in terms of much else.


Jim, W6RMK

(I'll be happy to send the 400kB Mil spec for TP to anyone who wants it...)




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