At Mon, 26 Feb 2007 09:22:06 +1030,
Kim Hawtin wrote:
> 
> Jim MacKenzie wrote:
> > The MMJ cable issue is the reason only one of my three VAXen is 
> > running right now.  I need to get a couple more.
> 
> i went down to my local electronics supply store, Jarcar and
> bought a packet of RJ11's ...

Well, just to be pedantic, that might be what Rat Shack calls them but
you don't want a real "RJ-11" connector -- it won't work in an MMJ plug
even with the tab filed off.  A real, plain, "RJ-11" is a six-position
jack but it only has two contacts.

The "RJ" prefix denotes "registered jack" (under USOC)

The closest thing with an RJ number is perhaps RJ25 (or maybe RJ19)
(AMP part number 5-631337-3)

I.e. You need all six contacts.  :-)

A real MMJ plug is an AMP 5-555237-2 part.  You need an AMP 853400-6 die
to crimp it properly.

If you want to avoid the weird USOC RJ numbers (which also specify the
use of each conductor) then the best way to describe these plugs and
jacks is by detailing exactly how many positions and contacts they have,
typically like this:

	4p2c		(typical: RJ22)
	6p2c		(typical: RJ11)
	6p6c		(typical: RJ25)
	10p8c		(typical: RJ45)

Note that RJ numbers don't just refer to those little plastic block
plugs and their jacks, but also to thing like the Amphenol miniature
50-pin for RJ21X or RJ2MB.

See, for example, http://xtronics.com/reference/10baseT.htm for lots of
other interesting details about USOC and related standards.

-- 
						Greg A. Woods

H:+1 416 218-0098 W:+1 416 489-5852 x122 VE3TCP RoboHack <woods@robohack.ca>
Planix, Inc. <woods@planix.com>       Secrets of the Weird <woods@weird.com>