Amplifier Research 75A250A Manual - Página 4

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Model 75A250A
2.1
G
ENERAL
Operation of the Model 75A250A broadband RF amplifier is simple. The amplifier's input signal, whether
swept or fixed in frequency, is fed into the jack labeled INPUT, and the amplifier's output signal is taken
from the jack labeled RF OUTPUT. The unit is turned on by activating the POWER switch. A circuit
breaker in the AC power line provides protection in the event of a unit malfunction. A polarized, three-
wire AC power cord is also included with the unit to provide cabinet and chassis grounding to the power
mains.
O
PERATION OF THE
SOURCE AND LOAD
UNCONDITIONALLY STABLE UNDER ANY MAGNITUDE AND PHASE CONDITIONS OF SOURCE AND LO AD
I
T HAS ALSO BEEN DESIGNED TO WITHSTAND INPUT POWER LEVELS UP TO TWENTY
RATED INPUT OF
TRANSIENTS WITH HIGH PEAK VOLTAGES CAN DAMAGE THE AMPLIFIER
CONNECTION OF THE AMPLIFIER
A
LTHOUGH THE
CONDITIONS DESCRIBED ABOVE
SIMULTANEOUSLY CAN CAUSE FAILURE OF THE UNIT
The Model 75A250A Amplifier is protected from input overdrive by a diode limiter on the RF input.
The Model 75A250A power transistors are protected from over-temperature by a sensor that senses the
heat sink temperature near the RF output transistors. In the event of a cooling fan failure or an air flow
blockage, the DC voltage will be removed from the RF stages; if and when the heat sink temperature
reaches approximately 70°C, the unit's front panel vacuum fluorescent display (VFD) will read
THERMAL FAULT. Normal operation can be resumed by resetting the Model 75A250A after the heat
sink temperature drops below 70°C.

OPERATING INSTRUCTIONS

M
75A250A
ODEL
V
S
OLTAGE
TANDING
1
W
M
WITHOUT SUSTAINING DAMAGE
'
S OUTPUT TO ITS INPUT CAN CAUSE OSCILLATIONS THAT WILL
PERMANENTLY DAMAGE ITS INPUT CIRCUITRY
M
75A250A
ODEL
HAS BEEN DESIGNED FOR THE OVERDRIVE AND LOAD TOLERANCE
THIS NATURE WILL NOT BE COVERED UNDER THE UNIT
SECTION II
C
:
AUTION
RF
BROADBAND
AMPLIFIER IS NOT CRITICAL IN REGARD TO
-W
R
AVE
ATIO
. H
OWEVER
N
:
OTE
,
SUBJECTING THE AMPLIFIER TO THESE CONDITIONS
'
S OUTPUT TRANSISTORS
(VSWR),
AND IT WILL REMAIN
(20)
,
SIGNAL LEVELS
. A
,
LSO
ACCIDENTAL
.
.
REPEATED FAILURES OF
'
.
S WARRANTY
Manual Text
.
TIMES ITS
> > 20
W
M
OR
2-1
REV A