Bell System 1013B Handset


Use

When the MON-TALK switch is operated to the MON position, the receiver is bridged across the line in series with a capacitor and a high-turns-ratio transformer.  The handset (in the monitoring position) introduces virtually no-bridging loss or phase shift for any frequency in the voice band.  This permits monitoring on all message, Wide-Area Data Network (WADS), Teletype Wide-area eXchange (TWX), program, or high-speed data transmission facilities without interrupting service.

When the MON-TALK switch is operated to the TALK position, the talking circuit bridge impedance is low and considerable loss is introduced when the handset is bridged across a working line.  The MON-TALK switch may be depressed momentarily to step switches, or for short talk periods, or locked in the TALK position by pressing down on the button and sliding toward the dial end of the handset.

The handset can be bridged either across the line or from either side of the line to ground.  The handset may be bridged into the circuit at any convenient location.

The transmit and receive levels of this handset are about 3 dB lower than a 500-type telephone set.