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160 School House Road, Souderton, PA 18964-9990 USA
Phone 215-723-8181•FAX 215-723-5688
MODEL 75A250A
75 WATTS CW
10 kHz - 250 MHz
with Versions M1-M4
The Model 75A250A amplifier is a portable, self-contained, air-cooled, broadband, solid state amplifier
unit designed for laboratory applications where instantaneous bandwidth, high gain and moderate power
output are required. Utilization of push-pull MOSFET circuitry lowers distortion, improves stability and
allows operation into any load impedance without damage. When used with an RF sweep generator, the
75A250A will provide a minimum of 75 watts of swept RF output power.
The Model 75A250A includes a front panel RF Gain Control, which permits the operator to conveniently
set the amplifier's desired output level. Housed in a stylish contemporary enclosure, the unit provides
instantaneous power for typical applications such as RF susceptibility testing, antenna and component
testing, Watt-meter calibration and as a driver for higher power amplifiers. The 75A250A is powered by a
high efficiency switching supply, with autoranging AC input circuitry which will automatically accept
voltages from 90 to 135 VAC, or from 180 to 270 VAC, in the 47 to 63 Hz frequency range. The RF
Amplifier stages are protected from over temperature by removing the DC voltage to them if an over
temperature condition occurs due to a cooling blockage or fan failure. The digital display on the front
panel indicates the operation status and any pending fault conditions when an over temperature or power
supply fault has occurred. The unit can be returned to normal operation when the condition has been
cleared; as with the other functions, this can be readily accomplished through a front panel switch. The
unit also includes digital control for both local and remote control of the amplifier. The 8-bit RISC
microprocessor controller board provides IEEE-488 (GPIB) and asynchronous full duplex RS-232
communication control of all amplifier functions.
75A250 TYPICAL POWER OUTPUT
120
100
80
60
WATTS
40
20
0
0.001
0.01
LINEAR @ 1dB COMPRESSION
0.1
FREQUENCY (MHz)
1 10 100 1000
CW
REV090503
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SPECIFICATIONS
Model 75A250A
POWER OUTPUT, CW
Nominal.............................................................................................100 watts
Minimum............................................................................................75 watts
Linear @ 1 dB compression ..............................................................50 watts minimum
FLATNESS............................................................................................± 1.0 dB maximum
FREQUENCY RESPONSE...................................................................10 kHz - 250 MHz instantaneously
INPUT FOR RATED OUTPUT............................................................1.0 milliwatt maximum
GAIN (at maximum setting)..................................................................49 dB minimum (See model configurations)
GAIN ADJUSTMENT (continuous range)............................................18 dB minimum
INPUT IMPEDANCE...........................................................................50 ohms, VSWR 1.5:1 maximum
OUTPUT IMPEDANCE.......................................................................50 ohms, VSWR 2.0:1 maximum
MISMATCH TOLERANCE ..................................................................100% of rated power without foldback. Will operate
without damage or oscillation with any magnitude
and phase of source and load impedance. (See Application Note #27)
MODULATION CAPABILITY..............................................................Will faithfully reproduce AM, FM, or pulse modulation
appearing on the input signal
NOISE FIGURE (above 1.0 MHz)........................................................16 dB typical
HARMONIC DISTORTION..................................................................Minus 20 dBc maximum at 50 watts
THIRD ORDER INTERCEPT POINT..................................................57 dBm typical
PRIMARY POWER...............................................................................90-135/180-270 VAC
47 to 63 Hz, single phase 400 watts maximum
CONNECTORS
RF (Type)..........................................................................................Type N female
(Location)...................................................................................See Model Configurations table below
REMOTE CONTROL
IEEE-488........................................................................................24 pin female
RS-232............................................................................................9 pin subminiature D (female)
REMOTE INTERLOCK........................................................................15 pin subminiature D
COOLING ............................................................................................Forced air (self contained fans)
MODEL CONFIGURATIONS
MODEL
NUMBER
RF CONNECTOR
LOCATION
GAIN
CONTROL
INSTRUMENT
CASE
WEIGHT
SIZE
(W x H x D)
OTHER
75A250A Front Panel Yes Yes 20.5 kg (45.0 lb)
75A250AM1 Rear Panel Yes No 16.0 kg (35.0 lb)
75A250AM2 Rear Panel Yes Yes 20.5 kg (45.0 lb)
75A250AM3 Front Panel Yes No 16.0 kg (35.0 lb)
75A250AM4 Front Panel Yes Yes 20.5 kg (45.0 lb)
50.3 x 15.5 x 37.6 cm
19.8 x 6.1 x 14.8 in
48.3 x 12.7 x 37.6 cm
19.0 x 5.0 x 14.8 in
50.3 x 15.5 x 37.6 cm
19.8 x 6.1 x 14.8 in
48.3 x 12.7 x 37.6 cm
19.0 x 5.0 x 14.8 in
50.3 x 15.5 x 37.6 cm
19.8 x 6.1 x 14.8 in
n/a
n/a
n/a
n/a
Operate mode at
circuit breaker on
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