The material contained in this document is the property of Electronics & Innovation Ltd., it is
subject to change without notice.
August 2012 8 Revision F
Chapter 3 Technical Description
3.1 GENERAL DESCRIPTION
The 1140LA is designed to amplify signals by 55 dB in the frequency band of 10
KHz to 2 MHz. The signal from the front panel N connector is fed via a length of
50 ohm coaxial cable into the input of the splitter module. The signal from the
output of the splitter is coupled to the input drivers 1) & 2) the first stage of each
is the MMIC front end. The output signal of the MMIC is coupled to the gate of
transistor Q1. The further amplified signal appearing at the drain of Q1 is coupled
to the input of Q2. This is transformed to 50 and fed to the driver output BNC
port.
The driver output signal are fed through a length of coaxial cable to the input of
two power splitters, the four outputs of this are each fed to the four amplifier
modules. In each PA module the signal is split into two equal phase and
amplitude signals. These signals are fed to the inputs of transistors Q1 and Q2.
The amplified signals appearing at the drains of Q1 and Q2 are then fed to the
output BNC port via the impedance matching network. The output of the modules
is then fed to the combiner to produce a single signal.
The power signal is then fed into a length of 50 ohm coaxial cable to the RF bi-
directional coupler. The output of the coupler is then fed directly to the N
connector on the front panel, this is the unit output.
The forward and reverse coupled ports of the bi-directional coupler are fed to the
RF detector which is situated on the main control board. The RF detector feeds a
voltage, which is representative of the true RMS power to the control board
proper. The control board in turn drives the front panel display.
There are four switch mode power supply units three provide a 48 VDC 24
ampere source. The other provides 48VDC and 24 VDC outputs and provides a
total of 24 amps. The main power supply also has a 5 VDC output which feeds
the control board.
