Tait T860 Series II, Service Manual

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M860-00-Preliminary
T867 General Information C1.3
Copyright TEL 30/06/98
1.1 Introduction
The T867 is a synthesised, microprocessor controlled FM base station exciter designed
for single or multichannel operation in the 220 to 285MHz frequency range. With a
standard power output of only 600mW, the exciter is designed for use with the T869
100W power amplifiers. The RF section of the exciter comprises a frequency synthesiser
which provides 100mW of frequency modulated RF drive to a two stage, wide band
output amplifier.
A wide selection of audio characteristics may be obtained from the audio processor.
Optional circuit blocks are an audio compressor and a pre-emphasis stage. They can be
bypassed or linked to one or both audio inputs, and then back into the remaining audio
circuitry in almost any combination. All audio processor options are link selectable.
The synthesiser frequency is programmed via the serial communications port. Eight
channel select lines are accessible via an optional D-range connector (D-range 2 -
T800-03-0000) at the rear of the set.
All components except those of the VCO are mounted on a single PCB. This is secured
to a die-cast chassis which is divided into compartments to individually shield each sec-
tion of circuitry. Access to both sides of the main circuit board is obtained by removing
each of the chassis lids. There is provision within the chassis to mount small option
PCBs.
The front panel controls include line sensitivity, microphone socket and carrier switch.
This switch turns on the carrier (unmodulated) as an aid to servicing.
The T867 is 60mm wide and occupies a single space in a Tait rack frame, which has the
ability to accommodate up to seven standard modules.