[GreenKeys] TTY loop jack boxes - SET, LPG, MISC

[Jim Haynes]

Another neat thing, if you can ever find one, is SB-66/FGC.  This is a
box with a 6x6 array of pushbuttons.  The CAA had something similar
called a push-key cabinet.  You connect six sets to one terminal strip
and six signal lines to the other.  Pushing a button connects the set
in that row to the circuit in that column.  To keep sets from running
open you put a loop supply on one of the signal line pairs and push
the buttons for the unused stuff to go into that line.  The switches
are complicated enough so that a signal line is never left open.

As for jack boxes, you want the loop current supply to be on the line
side of the box, not on the set side, because if you put it on the
sets you can't add a set in series with another set in a working line.
But that says any sets not in use have to be connected to a line with
a loop supply, or they have to be turned off.

 	---

 	"Ya can argue all ya wanna, but it's dif'rent than it was."
 	"No it ain't! No it ain't!  But ya gotta know the territory."
 		Meredith Willson, The Music Man