E&I 2500L User manual

The material contained in this document is the property of Electronics & Innovation Ltd., it is subject to
change without notice.
August 2012 Revision D
1
2500L
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.
August 2012 Revision D
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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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August 2012 Revision D
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Chapter 1 Introduction
The 2500L is a broadband solid state amplifier covering the frequency spectrum from 50
KHz to 12 MHz. It is rated at 500 watts of RF power with low harmonic and
intermodulation distortion. Over 800 watts of saturated power can be produced with
increased distortion products from 100 KHz to 12 MHz. A linear Class A design, the
2500L will amplify inputs of AM, FM, SSB, pulse and any complex modulation signals.
The amplifier has 60 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 200-240VAC 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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Table 1-1. SPECIFICATIONS
FREQUENCY COVERAGE:
50 KHz to 12 MHz
GAIN:
60 dB min, ±1.5 variation
CLASS A LINEAR OUTPUT:
500 Watts P1dB
SATURATED RF POWER OUTPUT:
800W Min. from 300KHz –12MHz
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 + 16dBm input
signal (1.0 Volts RMS) for all output load
conditions, without damage
POWER OUTPUT METER:
True RMS power detection. ±5% of full
scale accuracy
POWER REQUIREMENTS:
200-240VAC Single Phase 47-63 Hz
SIZE:
24 X 16.75 X 20 inches
330 X 425 x 508 mm.
WEIGHT:
180 lbs (82 kg)
CONNECTORS:
N
OPERATING TEMPERATURE:
0 –40 C
RACK MOUNTING:
Chapter 2 Operation
2.1 INTRODUCTION
The 2500L RF amplifier is used to amplify the RF level of signal sources in the
50KHz to 12 MHz range. No tuning or any other form of adjustment is required.
The 2500L 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.
2.2 RACK INSTALLATION

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This unit is 14U high, 16.75” width. With the handles removed it will fit into a
standard rack.
2.2.1 Mains Voltage
The unit runs of 200-240VAC Single Phase
2.3 OPERATION
A fixed line cord is supplied to form a connection between the mains supply and
the rear of the unit. This is configured from the factory with a 30A plug. Plug this
into 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 N plug to the load.
(iv) Connect the input signal via a 50 ohm coaxial lead and N plug to the
input connector.
2.3.2 Front Panel Display
The 2500L 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)
PSU fault (internal fault in the main switching power supply)

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August 2012 Revision D
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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 2500L 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.
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:
Figure 2.2: Example RS-232 setup using Hyper Terminal

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subject to change without notice.
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"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 2500L is designed to amplify signals by 60 dB in the frequency band of 26
KHz to 12 MHz. The signal from the front panel N connector is fed via a length of
50 ohm coaxial cable into the input of the pre-amp splitter module. The signal
from the output of the splitter is coupled to the input drivers 1) - 4) 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 a
power splitter, the outputs of this are fed to the power 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 a
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 five switch mode power supply units four provide a 42 VDC 35 ampere
source. The other provides 24 VDC outputs and provides 10 amps. The main
power supply also has a 5 VDC output which feeds the control board.

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subject to change without notice.
August 2012 Revision D
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Coupler
RF IN
RF OUT
To Page 2 c
RF Detect
2500L RF Amplifier
Splitter
Driver 1
24 Volt
To Page 2 a
To Page 2 b
To Page 2 b
42 Volt
42 Volt
2100L PA
2100L PA
2100L PA
Driver 1
Splitter
2100L PA
42 Volt
Splitter
Driver 1
24 Volt
To Page 2 a
To Page 2 b
To Page 2 b
42 Volt
2100L PA
2100L PA
2100L PA
Driver 1
Splitter
2100L PA
Combiner
Combiner
Combiner
2500L –SCH-01

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subject to change without notice.
August 2012 Revision D
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Chapter 4 Maintenance
4.1 INTRODUCTION
The E&I 2500L 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
16dBm.
This chapter therefore, deals only with certain fundamental procedures for fault
location.
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.

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subject to change without notice.
August 2012 Revision D
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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 30 KHz to 12 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 1000 watt attenuator to the output connector. Adjust the input
CW signal to any frequency between 30 kHz and 1 MHz for 500 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.
4.3.1 Measurement of Gain
1. Equipment Required (or equivalent):

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a) Osilloscope - Tektronix T921
b) Sweep/Generator - HP8601A
c) Signal Generator - Exact Model 7060
d) 50 ohm Detector - Wavetek D151
e) Attenuator, 30 dB, 1000 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 30 kHz and the sweep width to 12 MHz.
c) Disconnect the 2500L from the set-up and connect the
sweep/generator RF output directly to the 50 dB attenuator.
50 dB Attenuator
RF Detector
Sweep Generator
RF Output
Sweep
Signal
Trigger
30 KHz –12 MHz
Input

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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
step attenuator (CCW) so that the output is reduced by 50 dB.
g) Reconnect the 2500L into the test set-up of Figure 4-1.
h) Place the 2500L power switch to the "ON" position.
i) Observe the gain versus frequency sweep on the oscilloscope.
The average gain should be greater 60 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.
50 dB Attenuator
Sweep Generator
RF Output
30 KHz –12 MHz
Spectrum
Analyzer
Power Meter
30 dB
coupler

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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 50 kHz, for an
indicated output of 500 watts on the power meter.
b) Using the spectrum analyzer, check that the level of the carrier
harmonics is less than -10 dB with respect to the carrier while manually
scanning the frequency band of 50 KHz to 12 MHz. An indicated power
output of 500W 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. This unit
must be strapped to a pallet for shipping.
Chapter 5 Safety:
Do not remove ANY PANELS…Shock Hazard plus these panels are part of the
cooling system design. 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.