Electronics & Innovation A075 User manual

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change without notice.
October 2023 Revision E
1
E&I A075
Broadband Power Amplifier
HIGH RF VOLTAGES MAY BE PRESENT AT THE OUTPUT OF THIS UNIT. All
operating personnel should use extreme caution in handling these voltages and be
thoroughly familiar with this manual.
Do not attempt to operate this unit prior to reading this manual.

The material contained in this document is the property of Electronics & Innovation Ltd., it is subject to
change without notice.
October 2023 Revision E
2
Warranty
Electronics & Innovation Ltd., (hereafter E&I) warrants for the period of three years from
the date of original delivery, each unit to be free of defects in materials and workmanship.
For the period of 36 months E&I will, at its option, repair or replace defective parts so as to
render the unit fully operational such that it performs according to the original specifications;
free of charge to the original purchaser.
Should warranty service be required, the unit must be returned to E&I, freight cost to be
borne by the owner. If, in our opinion, the unit has been damaged by use outside the limits
prescribed in this manual or by accident, then the warranty shall not be honored. In such a
case E&I will provide an estimate for repair, assuming repair is possible and provide a
quote at standard service rates.
Contents
Chapter 1
General Information……………………………………………………………3
Chapter 2
Operation………………………………………………………………………..4
Chapter 3
Technical Information………………………………………………………….7
Chapter 4
Maintenance……………………………………………………………………8
Chapter 5
Safety……………………………………………………………………………12

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October 2023 Revision E
3
Chapter 1 Introduction
The A 075 is a broadband solid state amplifier covering the frequency spectrum from 300
KHz to 35 MHz. It is rated at 75 watts of RF power with low harmonic and intermodulation
distortion. Over 150 watts of saturated power can be produced with increased distortion
products. A highly linear Class A design, the A 075 will amplify inputs of AM, FM, SSB,
pulse and any complex modulation signals. The amplifier has 50 dB gain, it is
unconditionally stable and will not oscillate even with combinations of mismatched source
and load impedance. It is protected against failure due to output load mismatch and/or
overdrive.
RMS forward and reverse powers are monitored by a front panel meter. An integral power
supply permits operation from 115/230 single phase AC power.
1.2 INSTRUMENTATION IDENTIFICATION
Each amplifier is identified by a serial number tag on the back panel of the unit. Both the
model number and the serial number should be quoted to identify specific unit.
1.3 SPECIFICATIONS
Physical and electrical specifications are listed in Table 1-1 below

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August 2012 4 Revision D
Table 1-1. SPECIFICATIONS
FREQUENCY COVERAGE:
300 kHz to 35 MHz
GAIN:
50 dB min, ±1.5 variation
CLASS A LINEAR OUTPUT:
75 Watts P1dB
HARMONIC DISTORTION:
< -25 dBc at 75 watts output.
SATURATED RF POWER OUTPUT:
150W Min. from 300kHz - 4MHz;
100W Min. from 4 MHz - 35MHz
INPUT IMPEDANCE
50 ohms, VSWR, 1.5:1 Maximum.
OUTPUT IMPEDANCE:
50 ohms, VSWR, 2:1 Maximum
STs STABILITY:
Continuous operation into any load or
source impedance.
PROTECTION:
Unit will withstand a + 13dBm input
signal (1.0 Volts RMS) for all output load
conditions, without damage.
POWER OUTPUT METER:
True RMS power detection. ±3% of full
scale accuracy.
POWER REQUIREMENTS:
100 –240 VAC 47-63 Hz.
SIZE: .
5.3” x 16.5” x 18.4”
134.5 x 420 x 467 mm
WEIGHT:
35 lbs (16 kg)
CONNECTORS:
BNC
OPERATING TEMPERATURE:
0 –40 C
RACK MOUNTING:
Chapter 2 Operation
2.1 INTRODUCTION
The A 075 RF amplifier is used to amplify the RF level of signal sources in the 300
KHz to 35 MHz range. No tuning or any other form of adjustment is required.
The A 075 produces rated power output at its output connector, regardless of load
impedance. Any power reflected due to output load mismatch is absorbed in the
amplifier. Therefore, although the output impedance is 50 ohms (maximum VSWR:
2:1), the amplifier will work into any load impedance.

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2.2 RACK INSTALLATION
This unit is 3U high, 16.5” width. With the handles removed it will fit into a standard
rack.
2.2.1 Mains Voltage
The unit accommodates AC line voltages from 100 TO 240 VAC 47 –63 Hz
2.3 OPERATION
A line cord is supplied to form a connection between the mains supply and the rear
of the unit. Plug this into the AC input at the rear of the unit and the AC mains
outlet.
2.3.1 Proceed as follows:
(i) Ensure that there is at least 3” or 7.5 cm clearance at the rear of the unit
for air flow.
(ii) Ensure RF input voltage is not excessive
a. The 1 V rms indicated maximum input voltage is 5 times the level of
the input signal required to achieve maximum output. Input voltages
in excess of 2 volts peak may permanently damage the instrument.
(iii) Connect the output via a 50 ohm coaxial lead and BNC plug to the load.
(iv) Connect the input signal via a 50 ohm coaxial lead and BNC plug to the
input connector.
2.3.2 Front Panel Display
The A 075 front panel has a passive LCD display designed for simplicity and
ease of use. During initialization, the LCD shows the software revision. After the
amplifier is initialized, the LCD indicates Forward Power, Reflected Power, and
amplifier status (see figure 2.1).
Pf:___W Pr:___W
Status:________
Figure 2.1 : Front Panel Display
Where Pf refers to forward power, Pr refers to reverse power, and Status
indicates “OK” unless there is a fault condition, such as:
•Overheat (heat-sink temperature is too high for reliable operation)

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August 2012 6 Revision D
•PSU fault (internal fault in the main switching power supply)
In the event of a fault, the unit may be reset by cycling the power. In the case over
an over temp fault, ensure that the air inlet and out let are not restricted. If the fault
persists, please contact Field Service.
2.3.3 RS 232 Interface
The A 075 features a standard RS-232 serial interface suitable for connection to a
PC or host system. The communication protocol is extremely simple to facilitate
readback and control with readily available terminal programs such as Hyperterm.
The RS-232 link has the following parameters:
Baud rate: 19200
Data bits: 8
Parity: none
Stop bits: 1
Flow control: none
An example configuration using HyperTerminal on a PC is shown in figure 2.2.
Figure 2.2: Example RS-232 setup using Hyper Terminal

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August 2012 7 Revision D
In the default state, the RS-232 port will echo the same information sent to the
front panel LCD display, allowing a running datalog to be stored to disk using the
capture feature of the terminal program.
Single character commands can be sent to the amplifier to achieve the following:
"1" key enables telemetry (readback similar to LCD display) - this is the default
mode at power up
“2” key clears any faults and tries to start the supply.
“0” key disables telemetry (Complement to “1” key)
Custom commands and display lists can be implemented upon customer
request.
Chapter 3 Technical Description
3.1 GENERAL DESCRIPTION
The A 075 is designed to amplify signals by 50 dB in the frequency band of 300
KHz to 35 MHz. The signal from the front panel BNC connector is fed via a length
of 50 ohm coaxial cable into the input of the driver amplifier module. The signal
from the input of the driver iscoupled to the input of 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 is fed through a length of coaxial cable to the input of the
amplifier module. In the 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 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 BNC
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.

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August 2012 8 Revision D
The switch mode power supply unit provides a 48 VDC 24 ampere source. The
power supply also has a 5 VDC output which feeds the control board.
Chapter 4 Maintenance
4.1 INTRODUCTION
The E&I A 075 RF amplifier requires no periodic maintenance. The instrument is
unconditionally stable and is fail-safe under all load conditions. Damage can only
be externally caused by the incorrect selection of the AC supply voltage or by an
input signal in excess of the specified 1 volt rms equivalent to a power level of
13dBm.
This chapter therefore, deals only with certain fundamental procedures for fault
location.
J1
BNC 1
2
50 ohm
100W
PS1
PS_48V
+48V
110VAC_line
110VAC_neutral
earth_gnd
SELV 5V
Inhibit
SELV 5V ret
Inhibit_ret
DC_ok
DC_ok_ret
+48V_ret
50 ohm
+34dBm
J2
BNC
1
2
CP1
HF_coupler
RF_in RF_out
Fwd
Rev
PS2
HK_supply
+48_ in
+24V
+24V_fan
Gnd
IPA1
HF_driv er
+28V
RF_in RF_out
Gnd
RS232
Control
Port
Controller
Fwd_in
Rev_in
TX
RX
fp_tx fp_Vdd
fp_gnd
DC Status
PSU Enable
PSU Enable ret
DC Status_ret
overheat_rtn
overheat
gnd
gnd
+5V
J5
PA1
HF_PA
+48V
RF_driv e RF_out
Gnd
J7
LCD1
LCD
Data_in
+5V
+5V_LED
Ground
Front
panel RF
input
0dBm
J6
J2
J1
J4
P1
5
9
4
8
3
7
2
6
1
TS1
Thermal switch
1
2
AC In
1 2
3
<Doc> 2
2100L Amp Top Level
A
1 1
Title
Size Document Number Rev
Date: Sheet of
A 075 Top Level
A 075 -001

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subject to change without notice.
August 2012 9 Revision D
Performance limits quoted are for guidance only and should not be taken for
guaranteed performance specifications unless they are also quoted in the
Specification Section 1.2.
4.2 PERFORMANCE CHECKS
To determine the amplifier’s performance carry out the following procedure.
4.2.1 Initial Check
The following check can be made after repair and adjustments or whenever
the condition of the unit is in question.
a. Connect AC power supply. Switch on power and observe that the display
initializes.
b. Connect a sweep generator (HP 8601 or similar) capable of sweeping
the frequency range 300 KHz to 35 MHz, to the input connector.
c. Adjust the output level of the sweep generator so that a 50 ohm video
detector connected at the output of the unit will not be damaged by
excessive power output. (Reference section 4.4.1 for set up.)
d. Observe the gain versus frequency ripple on an oscilloscope calibrated
in decibels. The gain variation must be not more than +/- 1.5 dB over the
frequency range.
e. Connect a calorimetric power meter (HP435B or equivalent) through a
30 dB 200 watt attenuator to the output connector. Adjust the input CW
signal to any frequency between 300 kHz and 35 MHz for 75 watts
output.
f. Observe the harmonic distortion of the output, properly attenuated, on a
spectrum analyzer. The harmonic components contributed by the
amplifier should be better than 25 dB down from the fundamental.
(a) If the above items are found to be outside of the specification, check
the spectral content of the input signal. If this is a pure signal then the
unit needs to be returned to the factory for service.

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4.3.1 Measurement of Gain
1. Equipment Required (or equivalent):
a) Osilloscope - Tektronix T921
b) Sweep/Generator - HP8601A
c) Signal Generator - Exact Model 7060
d) 50 ohm Detector - Wavetek D151
e) Attenuator, 30 dB, 500 Watts Bird
Figure 4-1. Gain Measurement
2. Connect the equipment as shown in Figure 4-1, then proceed as follows:
a) Set the oscilloscope to DC, Time/cm to Ext. X,and gain to l0mv/cm.
b) Set the sweep generator to the video sweep mode with the start
frequency at 300 kHz and the sweep width to 35 MHz.
c) Disconnect the A 075 from the set-up and connect the
sweep/generator RF output directly to the 30 dB attenuator.
d) Adjust the output level of the sweep/generator for full vertical
deflection on the oscilloscope face.
e) Calibrate the scope face to show 3 dB in 1 dB steps by attenuating
the sweep/generator in 1 dB.
f) Return sweep/generator output level to full deflection. Rotate the

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step attenuator (CCW) so that the output is reduced by 50 dB.
g) Reconnect the A 075 into the test set-up of Figure 4-1.
h) Place the A 075 power switch to the "ON" position.
i) Observe the gain versus frequency sweep on the oscilloscope.
•The average gain should be greater 50 dB
•The gain variation should be within the 3 dB as shown on the
oscilloscope.
4.4.2 Measurement of Harmonics
Figure 4-2.
1.) Equipment Required:
a) Sweep/Signal Generator
b) Calorimetric Power Meter HP435B
c) Spectrum Analyzer.
d) Attenuator (30dB)
e) Coupler (30 dB)
2.) Connect the Equipment as shown in Figure 4-2, then proceed as follows:
a) Adjust the signal generator to a CW center frequency of 300 kHz, for an
indicated output of 75 watts on the power meter.
b) Using the spectrum analyzer, check that the level of the carrier harmonics
is less than -25 dB with respect to the carrier while manually scanning the
30 dB
coupler

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frequency band of 300 KHz to 35 MHz. An indicated power output of 75W
should be maintained during this operation.
4.5 PACKAGING FOR RESHIPMENT
In the event of the equipment being returned for servicing it should be packed in
the original shipping carton and packing material. If this is not available, wrap the
instrument in heavy paper or plastic and place in a rigid outer box of wood,
fiberboard or very strong corrugated cardboard. Use ample soft packing to prevent
movement. Provide additional support for projecting parts to relieve these of
unnecessary shock. Close the carton securely and seal with durable tape. Mark
the shipping container FRAGILE to ensure careful handling.
Chapter 5 Safety:
Do not attempt to operate this unit with the cover removed. High AC and DC
voltages are present. The cover protects against electrical shock due to AC line
voltages, high DC and RF fields. Further the cover provides part of the cooling
system design. Components, specifically on the RF driver board are prone to over-
heat and eventual failure if the unit is operated without the cover in place.
Ensure that the load is connected to the output prior to connecting the RF input to
the unit. This will prevent high voltages being present and exposed at the output
connector.
Only use the AC cord provided or equivalent.
Ensure that the mains outlet is properly grounded.