[GreenKeys] Jack Selection for TTY equipment

[Ralph Mowery]

At one time I had an aluminum box with a milliamp meter and loop supply I built in it.  I cut out part of it and put in a piece of plastic and mounted 6 of the 1/4 inch phone jacks.  They were closed circuits except for one.  I left that one as an open circuit jack so I could unplug from it and it would open the loop.  The plastic was to insulate the jacks.  The jacks were at the lowest or grounded part of the loop.  While it did not prevent a total shock, it would be onthe lower voltage part.  Also the tip of the jack was set up to be the most positive part of the circuit.
While not totally safe, it was the best I could come up with at the time with what I had to work with.
  ----- Original Message ----- 
  From: WA5CAB at cs.com 
  To: greenkeys at mailman.qth.net 
  Sent: Saturday, November 16, 2013 11:25 AM
  Subject: Re: [GreenKeys] Jack Selection for TTY equipment


  The problems with using dumb (i.e., with no switches) jacks are:

  1) The only way in which you can jack two or more machines in series is by using shorting plugs for when you don't want them in series.

  2) If you do it that way, everything runs open while you are getting it set up.

  3) If you have a machine, convertor or exciter normally wired into a loop, you can't take it out of that loop and patch into another one either with or without disturbing its default loop.

  You will be much better off if you locate and acquire something like a TT-23 TTY Panel.  I can't at the moment recall the nomenclature of the earlier one that I actually used for a few years.  looked like an overgrown TT-23.
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