[GreenKeys] Jack Selection for TTY equipment

Fri Nov 15 21:14:31 EST 2013

We fell heir to a group  of ADC  19 inch  Audio jack  panels   I am very 
tempted to use  these as a patch  panel   .. we have   several TUs  and a 
R-388,   some  scopes   a neat dual speaker set  in a 19"  panel...

I was thinking of having a  patch bay  for audio and    a separate one  for 
 loop.   

These things are  cool...   Has  anyone   sued  these ADC   panels  for 
loop  before!?

Ed Sharpe Archivist  for SMECC  _www.smecc.org_ (http://www.smecc.org)  

In a message dated 11/15/2013 6:57:21 P.M. US Mountain Standard Time,  
k1lky at earthlink.net writes:

On  Nov 15, 2013, at 7:49 PM, Cory Heisterkamp <_coryheisterkamp at gmail.com_ 
(mailto:coryheisterkamp at gmail.com) >  wrote:

Evening Greenkeyers,

I wanted to solicit your  advice with a project I have in mind. My current 
TTY arrangement Involves  lots of exposed conductors, alligator clips and 
random wires. I'd like  to tidy things up and build my loop supply into an 
enclosure with ammeter.  Seeing as most of my equipment has quarter inch plugs, 
I'd like to  build a series of jacks into the front of the unit to allow me 
to mix and  match equipment. 

I'm wondering, are there certain types of  jacks I should be on the lookout 
for? Won't the traditional style with nut  bonded to sleeve create a shock 
hazard? Your thoughts?

Cory,  

I have a strong opinion:

Find and procure a small wooden box that will do all you need.  It’s  
called the "63 C 1 Telegraph Loop Switchboard" and was used by Western  Electric 
for teletype customers and by the military also.  This little  wizard is 
about 5 inches wide and 8 or 9 inches tall and maybe 4-5 inches from  the 
business panel to the back.  It has 4 rows of jacks: these are  labeled LPG1 
(looping 1) LPG2 (looping 2), SET, and the fourth is either SET  or MISC.  
Inside there are terminal points to hook wires to.  The  jack types used are type 
303A and 438C.  The different jacks accomplish  wondrous switching as you 
plug and unplug the patching cords used with it.  The cords are simple 
tip-sleeve two conductor cords with 347 plugs on  each end (I assume that common 
phone plugs work fine.)

Basically, with nothing plugged in, the incoming LINE is connected to  it’s 
particular SET.  The box accommodates four LlNES with the four SETs.  The 
SET might well be a send-receive teletype such as a Model 15.

The LOOPING jacks let you insert another device into the loop - say a  
Transmitter Distributor, or a tape reader.  The MISC circuit lets you  insert 
into a loop whatever is connected to that jack, such as a loop current  meter 
or maybe a loop supply.

I have puzzled over the various ways this thing can be used, and came to  
the conclusion that a LOT of equipment can be set up and inter-operated with  
this apparently simple box.

Note that the jacks used, especially the 438 C jack, does  
make-before-break and disconnect functions that are needed to prevent opening  a loop when 
you don’t want to.  (You won’t find these jacks at Radio  Shack!)  Oh, the 
panel on this thing is bakelite and it would not do to  mount the jacks in a 
metal panel.

I will attempt to attach a picture of the thing, and won’t be surprised  if 
it does not make it out to the list.  I have pictures of both the box  and 
the circuit diagram from inside one of them.

Roy

Roy Morgan
_RoyMorgan at alum.mit.edu_ (mailto:RoyMorgan at alum.mit.edu) 
K1LKY Since  1958 - Keep 'em Glowing!

=

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