Tait T830 Series, Service Manual

Page: 269 / 284

Copyright TEL 31/01/96
2 T836/837 Optional Features
2.1 Audio Processor
The T836 and T837 come with a number of link selectable features which give added
system flexibility.
Refer to Section 3.3 in Part C for further details.
2.2 Line Transformer Inputs And Outputs
The line transformer (T100) is designed to provide a balanced interface to 600 ohm lines.
For normal operation the two centre connections (LINE I/P 2, LINE I/P 3) are shorted
together, and the 600 ohm line is connected between LINE I/P 1 and LINE I/P 4.
The secondary winding of the transformer is connected via a 1k resistor to pin 7 of the
D-range connector and may be used to monitor audio on the line. It is normally shorted
at the connector socket to pin 6 to route the audio signal back into the processor. If
required, the audio path may be broken at this point for use with signalling options, e.g.
CTCSS (refer to TI-346).
2.3 Opto Key
The keying circuitry may be completely isolated from the rest of the system by means of
the optocoupler (IC100) connected between pins 11 and 12 of the D-range connector. A
constant current source (Q106) allows keying voltages between 6 and 50V.
2.4 Relay Driver
A dedicated transistor (Q105) is provided for the purpose of switching an external (e.g.
coaxial) relay. The output is open collector and is activated by the Tx-reg rail.
This output is not normally connected to the standard D-range connector, and use of the
relay driver will necessitate manual wiring to an additional D-range connector, as sup-
plied with the T800-03 auxiliary D-range.