[GreenKeys] A neat item, if you can find one

[Jim Haynes]

This item is SB-66/GG or SB-66/FGC.  The C.A.A. had a similar item
called a push-key cabinet.  It's a switchboard for connecting up to
six TTY machines to one of up to six current loops.  It keeps the
loops closed at all times.

The F.A.A. quit using them because when they got Model 28 machines
they made extensive use of things in the stunt box.  Thus they needed
to switch a lot more circuits than just the loop to switch in a spare
machine while the normal one was down.  So the replacement for this
little box turned into a 7-foot relay rack.

The F.A.A. was one of the first to make extensive use of the Model 28
stunt box as a replacement for the separate SOTUS machine used with
Model 15 equipment.  The machines typically were equipped for selective
calling, meaning they would print a message preceded by the three-letter
call sign of the airport or other facility.  And they could also use
signals to control starting a tape reader.  In selective calling the
machine sits there sounding busy but not printing anything while traffic
for other stations is on the wire.  These machines are usually 28 RO
and have a local/remote switch on the front blister.  The local position
turns on a solenoid that overrides the selective calling print suppression
so the machine prints everything on the wire, which is required for
weather data service.

There I go again starting with one topic and going off into another one.

 	---

 	"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
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