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991.006.04 I1-se

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

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