[GreenKeys] jackfields

[WA5CAB at cs.com]

One comment I'll add on TTY jack panels or patch panels with TS jacks. The 
positive loop supply goes to the top of the five or six loop panel to the top of 
the 2500 ohm 25 watt rheostats. The jacks are normally wired with tip to the 
top of the panel and equipment or machine jacks were equipped with switch 
contacts such that the bare loop supply never appears on the end of a patch cord 
plugged into one of those jacks. Generally, converters like the AN/URA-6, 
7,8,17 were wired to the bottom of a loop or to unpowered jacks. Plugging a patch 
cord into any equipment jack shorts it out of its column and puts whatever now 
unpowered device is wired onto that jack onto the patch cord. What were called 
I think Seriesing jacks are wired the other way and were usually the top two 
or three jacks in a loop. At least in the older patch panel I have and the 
Korean War vintage ones on most ships I served on. The switches on these jacks 
are wired to short across the jack with nothing plugged into it. If you plug 
into one of these with a cord not plugged into anything else, you would (a) open 
that loop (and cause any other machines on the loop to run open and probably 
enjoy a nice one way conversation with your Division Chief or the CWO) and (b) 
put the loop supply voltage on the tip of the loose plug on the other end of 
the patch cord. So you didn't do it that way. First you jacked into the machine 
you wanted. Then you jacked into the loop you wanted.

Maybe someone can refresh my memory, which just went indeterminate. Isn't a 
Normalling jack one wired such that plugging a patch cord into it puts the 
equipment wired to to the jack onto the patch cord and shorts the loop across the 
jack? Or am I mixing audio with TTY terminology?

Anyway, my point is that in a TTY patch panel, generally the positive 120 VDC 
loop supply does not appear on the sleeves of jacks or patch cords. 

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480
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