Print Date 12/05/15 Page 5 of 32 S7600-00MA-08
SECTION ONE : INTRODUCTION
! CAUTION !
These Transmitters operate at
high RF power levels, internal supply energy levels and mains
supply current levels
. They also incorporate devices containing
toxic BeO
. Installation, operation
and maintenance of this unit must therefore, only be carried out by suitably qualified personnel,
familiar with and fully utilising the safety procedures such equipment demands.
NO
attempt at installation should be made without full reference to and compliance with SECTION
TWO : INSTALLATION.
NO
attempt at internal maintenance should be made without full reference to and compliance with the
appropriate sections (apart from fuse changing which is detailed in INSTALLATION).
1.1 : GENERAL DESCRIPTION
The S7600 Series of Low Power FM Transmitters provide output powers of up to and including 2kW
(used singly) or 4kW (using combined pairs) in the standard Band ll frequency range of 87.5-108MHz.
They are normally supplied with either one or two Exciters, capable of generating a standard mono or
stereo FM signal from a variety of analogue or digital audio or data sources (including left/right audio,
MPX, RDS, SCA, DARC etc.). It is important to note that the Exciter(s) supplied will depend on the
user’s actual requirements in this regard which, therefore, must be clearly specified at time of ordering.
The Transmitters are totally self-contained (including forced air-cooling) and can be mounted as a
complete unit (less Exciters) within a standard 19 inch rack with at least 600mm depth and 12U height
(up to 1kW) or 14U (up to 2kW). Pairs (including drives) can be accommodated in racks of 42U height.
All that is required is a connection to a mains supply, to an antenna and to the Exciter/Drive(s). When
used in pairs, to generate up to 4kW, an additional two-way splitter, combiner and approximately 1kW
balance load is also required. In this situation, additional manual ‘patching’ or manual/automatic
switching can be provided, as an option, to direct all of one Transmitter’s power to the antenna.
The key feature of The S7600 series is its ability to remain ‘on-air’. The use of multiple Amplifier and
Power Supplies Modules and dual power supply and control circuitry means that if failures do occur, it
normally only results in a reduction of output power. Furthermore, the lightweight, hot-pluggable
Amplifier and Power Supply Modules can be easily replaced, in seconds, without having to go ‘off-air’.
Provision for dual Exciter/Drive automatic changeover and for connection to a second active/passive
reserve S76XX or S79XX (i.e. 500W to 10kW) Transmitter is also made, further enhancing the ability
to remain ‘on-air’.
Each Transmitter consists of a number of modules described as follows (1.1.1 – 5 inc.). Front and rear
views, block and circuit diagrams, showing these modules are bound at the rear of this manual
(S7600-01GA S7600-02GA, S7600-03GA, S7600-04GA, S7600-00BK and S7600-00CT).
Workshop editions of this manual contain extra information, also bound at the rear, which gives
detailed test procedures, circuit diagrams, assembly diagrams, layouts and parts lists.
1.1.1 : E2021 300W Amplifier Module
Two (on S76005 500W) four (on S7601 1kW) or eight (on S7602 2kW) of these are provided, each
with their own independent control and monitoring circuitry. This circuitry includes reverse power,
supply current and temperature monitoring to shut down and protect individual modules. Failures in a
single Amplifier Module only tend to give a reduction in power, with the Transmitter still operating with
several modules having failed (in the S7601 and S7602).
Each Amplifier Module can be removed or replaced whilst the Transmitter is operating (‘hot-
pluggable’). This feature means that if failures do occur, modules can be replaced within seconds,
without having to go ‘off-air’. Red/green fault displays on the front of each module help indicate the
faulty module to be replaced, this normally restoring the Transmitter’s full output without any further
immediate technical investigation being required. The relatively low weight and small size of each
module assist their actual transport to site.
