13 Sep
2013
13 Sep
'13
12:06 a.m.
On Fri, 6 Sep 2013, Tony Duell wrote:
Siemon makes a UP-2468 modular plug which is a narrow body 8P8C that can
plug into a 6P6C (or any other 6PxC) jack. I use these with some of my
telecom test gear and banjo adapters. A standard 8P8C WE/SS (Western
Electric/Stewart Stamping) dieset works fine with them. The latching tab
isn't protected though, so in cases where it might snag on something you'd
want to use one of Siemon's standard 8P8C boots with these plugs.
http://www.siemon.com/e-catalog/ECAT_GI_page.aspx?GI_ID=mpc_universal-modul…
No, generally
one should not use a smaller modular plug in a larger
modular jack. Most plugs do not have relief slots next to the outermost
contacts and the polycarbonate plug body will permanently deform the
outer contacts in the modular jack. This happens a lot with 8P8C (RJ45)
jacks that people attempt to plug phones into that use 6P4C, 6P2C, etc
(RJ11) plugs.
Agreed.
My telephone line simulaotr [1] has 8p8c sockets for the 2 devices you
want to conenct (telephones/modems/,,,). The mode I normally use
similates a normal 2 wire telephone line on the middle pair of contacts
of each connecotr.
Yes, you _can_ plug a 6p2c or whatever in there and it will work. But
when I tried it it wasn't that secure and it seemed to be straining the
outer contacts. I made up a couple of adaptors w~~ith 8p8c plugs on one
end and 6p4c sockets on the other (middle 4 cotnacts of the 8p8c wired). [1] On-topic? I bought it to test old modems and
prestel sets (althohuh
I am also interested in old telephones in general). It contains 6
microprocesosrs (3 off 8085, an 8041, an 80-49 and a TMS320) and has
RS232 and IEEE-488 interfaces. I don;t think it's user programamble,
though. It's almost a classic computer :-)
I can confirm that Bell originally didn't intend for customers to unplug
the small square modular connectors. Back then they would actually tell
customers not to unplug them and that the connectors were fragile and
could break if unplugged. Bell instead wanted subscribers to use the large
4-prong plugs for phones that would be unplugged and moved room to room.
Where subscribers didn't intend to move phones, standard RJ11 jacks were
installed much the way they are today.
Originally, Bell System phones were hardwired, and later on the large
4-prong plugs became available since subscribers wanted to be able to move
a phone from room to room (remember, back then you couldn't "own" your own
telephone and each phone had to be leased from Bell). For normal single
line use, the 4-prong variety were used, but there were also some plugs
with many more pins for commercial multi-line phones. With some of the
older single-line phones, the green/red wires were the standard tip/ring
and yellow was used for a ground (bonded to earth at the carbon
protector). Later, they did away with the dedicated earth ground and used
black/yellow to optionally supply low voltage AC (~8V) for phones that had
lighted dials (and for the lamp in the base of the Princess line of
phones). Even that still only needed 4-wires. The 4-prong plug to
RJ11/RJ14 jack adapters came about later, probably around the same time
they introduced modular plugs.
WE 225A [Bell System logo] "Not For Sale"...I thought I still had one of
those adapters in the desk drawer somewhere ;)
There /are/ a few 6P type modular plugs out there
that do have relief
openings that will somewhat fit 8P8C jacks, but they are very uncommon.
The plug fit is still loose and it isn't something the modular plug
standards (from Bell System) ever really intended.
As an iaside, I think I read soemwhere that the original intention was
not to use the modualr plugs as the conenction betwene cable and wall.
The wall socket would remain the 4 pins in a trapezium one. The
telephone would consist of 5 'modules' (hence the name 'modular
connecotrs' -- the base, the handset, the handset cagble, the line cable
and the 4 pin plug. The last would have a 6p4c socket on the side to
plug the line cable (OK, 'desk cord') into The modular connectors would
not normally be unplugged (e.g. when moving a telephone from oen room to
another), they were only used for maintenance and repair.