991 Division (8 Digits Series) - TCI Library

991.006.01 I1-se

(Anonymous) — Thu, 03 Dec 2009 08:25:52 -0800

PBX Systems - Range Chart - Trunk and Station Conductor Loop
Ranges for PBXs Connected To No. 1 Crossbar Central Offices Having
1300-Ohm Subscriber Conductor Loop - 400-Ohm Talking Battery Feed
Circuit - AC-DC or Superimposed Ringing (84-88V AC Component) - Office
Voltage of 48V (Floating), Issue 1, 1960-03-01

991.006.04 I1-se

(Anonymous) — Thu, 03 Dec 2009 08:25:52 -0800

PBX Systems - Range Chart - Trunk and Station Conductor Loop
Ranges for PBXs Connected To Panel Central Offices Having 635-Ohm
Subscriber Conductor Loop - 50-Ohm Talking Battery Feed Circuit - AC-DC
or Superimposed Ringing (72, 80, or 84 Volts Minimum AC Component) -
Minimum Office Voltage of 21V (Floating), Issue 1, 1960-05-01

991.102.02-se

(Anonymous) — Tue, 24 Nov 2009 09:12:08 -0800

608A Private Branch Exchange - General Description, Issue 1,
Feb. 1960 (Caution: 5MB due to photos)