[GreenKeys] TTY Jack Bays

[wa2hwj at att.net]

ZCZC

I think most TTY jack bays have these designations:

LINE - a multi-contact jack that attaches the line to the plugged-in
connection and cuts out the LOOP and SET jacks. Depending on how
fancy you want to get, the jack could also put the TTY (SET) onto a
dummy loop which could be monitored through the LOOP jack.

LOOP - a standard closed circuit jack that puts the plugged-in connection in
series with the incoming circuit (loop) and the TTY equipment. This is used
for series monitoring with another TTY, loop current meter, distortion set, etc.

SET - this is another multi-contact jack that attaches the TTY to the plugged-in
cable and cuts out the LOOP and LINE jacks. I believe this would
provide a short to the LOOP through the LINE jack.

The small jackboxes from Bell have four sets of these jacks, allowing for
patching of a wired-in TTY to another wired-in LINE, etc. In the
"normal" condition, up to four lines would go up to four TTY's, for example,
and there would not be any patch cables in use. So, you'd have
LINE > LOOP > SET. By using a patch cable,
you could patch LINE 1 to TTY 3, and so on. There's also an
extra jack for each row which can be used for miscellaneous
connections (such as the dummy loop). I think the jack is
labeled MISC.

Some of the long-frame jacks used in these patch bays have
an unbelieveable array of extra contacts, some of which are
make-before-break types.

73,

Jack WA2HWJ

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