Clear-Com AB-120 - Manual (Page 10)

Clear-Com Communication Systems
AB-120 Announcer Console Instruction Manual
1 - 4
Line Output Level Select
The operating level at the output is selectable to accommodate the
various types of devices that are to be fed. The microphone input of a
console would need -60 dBu whereas the line input of a console might
need a level of -10 dBu.
Jumper JP8 allows the selection of three gain structures for the output
amplifier and the output connector so the rear panel can be plugged
into an alternate header on the printed circuit board that has a 30 dB
pad inserted in the output. The combination of JP8 and the 30 dB pad
allows an output level selection from 0 dBu to -50 dBu in 10 dB steps.
The output gain is normally factory set to -10 dBu.
Options for Power
The AB-120 can be powered from the intercom line, the IFB line, or
from a local external DC supply. To power it from the intercom line of
the IFB line, the unit needs a minimum of 25 VDC. The AB-120 draws
approximately 100 mA of current with peaks of 120 mA.
The following topics describe how to power the AB-120 from the three
different sources.
Power from the IFB Line
To power the unit from the IFB line, set jump jacks on pins 2 and 3 of
JP5. JP5 selects where the positive DC power is sourced from.
If for noise reasons, pin 1 of the IFB input connector can not be
connected to power ground of the AB-120, the power cannot be
derived from the IFB line.
Power from the Intercom Line
To power the unit from the intercom line, set jump jacks on pins 1 and 2
of JP5. JP5 selects where the positive DC power is sourced from.
Power from an External DC Supply
If power from the intercom line or IFB line is not available then plug in
the DC supply supplied with the unit.
0dBu -10dBu -20dBu -30dBu -40dBu -50dBu
Output Connector J2 J2 J2 J3 J3 J3
JP8 Position Open 2-3 1-2 Open 2-3 1-2