[time-nuts] Power connectors continued

jimlux jimlux at earthlink.net
Fri Jun 23 20:02:38 EDT 2017

On 6/22/17 4:22 PM, William H. Fite wrote:
> A good friend of mine, sadly of blessed memory, was a lead engineer for
> Grumman on the comm systems of the lunar lander. He spoke of small
> space-rated multi-pin connectors that cost upward of $500 each.
The Micro-D is widely used in spaceflight, and is a pox on the connector 
world - not only are they expensive, the way the pins and jacks are made 
is almost asking for damage - the pin is shrouded in a hole, and the 
jack is exposed. $100 for a 9 pin wouldn't surprise me.

Lately, I've been encountering nano-D (Glenair, Omnetics) - they're not 
as delicate, they're smaller.

> On Thursday, June 22, 2017, Arnold Tibus <arnold.tibus at gmx.de> wrote:
>> Hello,
>> I can second Magnus and want to throw in some more details.
>> Cannon, Deutsch, Bendix, Souriau, Matrix, Amphenol,  etc. etc. are (big)
>> companies manufacturing all kind of connectors and are  n o t  connector
>> type designations! Important are the type numbers of the manufacturer or
>> higher level specification numbers.
>> We used in the aircraft and spacecraft business naturally the military
>> (MS-) numbers listed in the MIL-QPL (or eg. for Spacelab with GSFC spec.
>> no). Most types of connectors are under these numbers available from
>> different manufacturers, of course with different manufacturer in house
>> part numbers. Attention: the 'same' connectors may be bought w/o the
>> Mil.-spec. sheets with somewhat lesser quality. Important details are
>> the max. mating number, the contact resistance (e.g. 20 mOhm) and the
>> max. continuous current, max. Voltage, vibration resistance and
>> reliability etc.  Of course, this makes good connectors somewhat
>> 'expensive'. Hirel and non-magnetic gold plated D- subminiture type
>> connectors do survive e.g. the rocket launch phase (high vibrations),
>> vacuum and low temperatures and are still used for space projects.

AMP (and others) sell a lower cost version called the "Circular Plastic 
Connector" or CPC. A coarser screw thread than the round metal MS 

The round connectors (called Bendix connectors by some at JPL, because, 
of course, that was the mfr for some batch of them) have a nice mil-std 
to define them.  There's a Shell, an Insert, and pins/jacks.  You can 
get shells and inserts with different keys and "clocking" to prevent 
mismates. There are coax and triax inserts, high voltage inserts, etc.

While they're pricey brand new, there are numerous surplus suppliers 
(Apex Electronics in Sun Valley, CA used to have thousands of them).

You can get them hermetic, vacuum tight, waterproof, locking, 
non-locking, every kind dielectric imaginable, etc.

>>  The D-sub series of connectors was introduced by Cannon in 1952. They
>> are still available as standard, hirel, and non-magnetic versions. The
>> contacts were machined contacts forcrimping or soldering connection and
>> made of massive copper with gold finish. (more see e.g.
>> https://en.wikipedia.org/wiki/D-subminiature). Example for the standard
>> 9 pin connector designation (crimp): DEMAM-9S and DEMAM-9P. Today are a
>> big number of companies producing equivalent types. Cheap ones are
>> equipped with contacts made of sheetmetal. Nobody should expect then the
>> same spec. values as reliability, mating numbers, contact power rating etc.
>> It is up to the designer of a product to be informed and select the
>> right quality device for his product ...

My problem with D-sub is two fold:
1) making a chassis hole is a pain - although now, with places like 
Front Panel Express, it's less so.
2) the shroud around the plug/male gender is easy to bend if it gets 
stepped on.  Sure, for flight hardware, carefully handled under the 
watchful eye of QA, not an issue, but I have lots of these from my 
not-entirely-mis-spent youth that are bent.

They do come with removable pins/jacks, and you can get coax flavors too.
They're fairly compact in a panel.

Other connectors of interest are those made by Lemo and Hirose.  Lemo 
are locking, pretty rugged when mated, and small for the number of 
conductors.  You see them on high end video and medical gear.

There's also something about double banana plugs and mating jacks. I go 
back and forth between PP and banana plugs for preference.

BTW, there are panel mounts for PP.

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