Re: Looking for comments on the 15-pin ethernet connector


Quayle (ihnp4!ihlpe!billq@ucbvax.Berkeley.EDU)
17 Jun 88 06:52:54 GMT


In article <8806151700.AA03253@ucbvax.Berkeley.EDU>, brescia@PARK-STREET.BBN.COM (Mike Brescia) writes:
#
# > I am looking for feedback on the quality and reliability of
# > the slide latch mechanism used on the DB-15 ethernet connectors.
#
# > The Society of Motion Picture and Television Engineers has a
# > standard known as RP-125 which specifies a parallel digital
# > television interface. The connector for that interface is
# > a 25 pin D-type (DB-25) with a slide latch like the ethernet
# > connector. The RP-125 standard is up for revision, ...
#
# So far, I have seen people flaming the slide latch, but no comment on the
# Dtype connectors. While using screws to replace the slide latch helps in some
# cases, the main problem seems to be that the long, narrow connector with 2
# rows of pins cannot withstand stress from a heavy or thick or stiff cable.
# There should be some analysis of why you should not use cable that is an inch
# in diameter to contain 18 individually shielded twisted pairs for your
# rs422/rs449 and try to connect it with a DC-37.
#
# The slide latch can only handle a little stress on the long dimension, and can
# handle none on the narrow dimension. The DB15 would be ok with a ribbon
# cable, because the ribbon is both light and flexible, and a well fitted slide
# latch would lock it in place, but then you would not even need a lock because
# the friction of the connector would keep it it.
#
# So, if SMPTE is going to do it right, they need to consider the mechanical
# characteristics of the locking mechanism, as well as the ease of connection
# and disconnection.

Outside the Ethernet realm, and in an industry that required a connector that
would withstand strain due to cable motion, we used an Amphenol MS connector.
For those unfamiliar, this is a round, keyed connector, with a screw-on shell.
Those things would withstand any ammount of cable motion (not to mention some
pretty nasty envrironmental hazards), without the least bit of wear or loss of
contact.

BTW, as our net grows to nearly fifty nodes, I'm still the only one I trust
manufacturing and installing those $*^%*&^*$ drop cables!!!

W.R. Quayle
AT&T Bell Labs.

Disclaimer: I have no connection (beit slidelock or otherwise) to any company
mentioned in my reply. My ideas are my personal feelings only!



This archive was generated by hypermail 2.0b3 on Thu Mar 09 2000 - 14:42:31 GMT