Tait T830 Series, Service Manual

Page: 111 / 284

Copyright TEL 31/01/96
1.1 Introduction
The T836 is a synthesised, FM base station transmitter for single or multichannel opera-
tion in the 136 to 174MHz frequency range with a standard power output of 25W. The
RF section of the transmitter comprises a frequency synthesiser which provides 170mW
of frequency modulated RF drive to a two stage, wide band output driver followed by a
25W power amplifier.
A thermal shutdown feature is provided in the T836 should operating temperatures
exceed acceptable levels.
The T837 is a synthesised, FM base station exciter for single or multichannel operation
in the 136 to 174MHz frequency range. With a standard power output of only 800mW,
the exciter is designed for use with the T838 50W power amplifier. The RF section of the
exciter comprises a frequency synthesiser which provides 170mW of frequency modu-
lated RF drive to a two stage, wide band output amplifier.
The synthesiser frequency is programmed via an EPROM which is attached to a sepa-
rate plug-in memory PCB. A DIP switch on the memory PCB allows fast single channel
selection from a multichannel programmed EPROM, but for true multichannel capabil-
ity the EPROM must be addressed separately via an additional D-range connector at the
rear of the set.
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.
All components except those of the VCO and memory PCBs are mounted on a single
PCB. This is secured to a die-cast chassis which is divided into compartments to indi-
vidually shield each section 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.