10 Oct
2010
10 Oct
'10
2:29 p.m.
A bit more on the shorting switch on your tester.
It's called an "exclusion key switch" and is used to prevent an
attached device from connecting to the line. Take a look at page 17
ff. in the UDS 208 modem manual:
http://www.arcelect.com/208A-B_manual.PDF
Those of us old enough to remember Ma Bell's setups will recall that
this switch was a little transparent (IIRC illuminated) knob on the
desk set that one turned to enable the modem to access the phone
line.
I can see why this would be part of a tester.
--Chuck