Print Date 31/08/11 Page 5 of 22 E2136-00MA-02
SECTION ONE : INTRODUCTION
! CAUTION !
These Amplifiers 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 XA500 Series of Low Power FM Amplifiers provide output powers of up to 500W (used singly) in
the standard Band ll frequency range of 87.5-108MHz. They can be supplied with either one or two
Exciters (with automatic changeover unit, ‘E2075’) 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
Amplifiers may also be supplied as pairs, with a XC2000 Combiner, generating up to 1kW, again with
one or two drives.
The Amplifiers 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 3U height.
All that is required is a connection to a mains supply, to an antenna and to the Exciter/Drive(s).
The Amplifier consists of a number of modules described as follows (1.1.1 – 7 inc.). Front and rear
views, a block diagram and a circuit diagram showing these modules are bound at the rear of this
manual (E2136-00GA, E2136-00BK and E2136-00CT).
1.1.1 : Power Supply
Depending on the variant, one or two ‘hot-plugable’ E2322 Power Supply Units are provided
(removable from the Amplifier front panel) each with its own forced air cooling, output control and
monitoring circuitry with status indicators. These highly efficient, switched mode units generate a
regulated 50V dc supply, of up to 42A total, from mains supplies of 110 to 260V, with the input power
factor approaching 100%. 50V dc outputs for each Amplifier Pallet and for all the low current circuits
are provided via separate fuses within the Amplifier. These fuses, as well as circuitry to measure total
supply current and monitor DC supply and fan status are fitted on the Power Supply Board, at the rear
of the Power Supply Units. On variants fitted with two switched mode units, if one should fail, the
XA500 will continue to deliver full output power. E2136-05, 06, 07 and 08 variants have a mains
supply on/off switch situated on the rear panel.
1.1.2 : Input Splitter
This connects the RF input N type connector to the two amplifier ‘pallets’ The splitter section is a two
way Wilkinson utilising standard 75
Ω
coaxial cable and two 50
Ω
load resistors
1.1.3 Amplifier Modules (‘Pallets’)
Two amplifier modules are provided, each contributing one half of the total output power. Each
amplifier module is an integrated 50
Ω
gain block consisting of a dual RF Mosfet transistor (in ‘push-
pull’) with matching sections at its input and output. This ‘pallet’ is mounted on an aluminium block and
is easily replaced as a unit if required. Amplifier modules (as well as input splitting and output
combining/ filtering circuitry) are mounted on a heatsink, which is forced air cooled by two fans directly
supplied from the Power Supply units. To reduce ingress of dust, nearly all of the forced air is directed
