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4.2.4 Modulator 1 Transmitter
The modulator
receives
the coded train
of
pulses
from the encoder and signais the transmit tube which
oscil\ates at the transmit frequency
of
1090 MHz. The rep\y signal from the transmit tube
passes
to
the
transponder antenna via a
low
pass
filter and
is
transmitted. When the transponder
is
switched
from
OFF
immediately
to
ON,
AL
T
or
TEST, i.e., by
passing
the SBY position, overloading
of
the transmit tube
is
avoided
by
the cavity protection circuit provided at the inputs
of
the modulator.
4.2.5 Self-test
Feature
(TEST)
ln testing proper functioning
of
the transponder the video decoder
is
switched
into
circuit
and the noise
output
of
the receiver applicd
to
the decoder input. The signal
is
identified
by
the decoder
as
random
interrogation.
When
al\
circuits
are
functioning properly, the
re
ply
lamp control
is
activated
to
cause
the
reply lamp
to
indicate whether the encoder
is
being signaled.
To
effect simulated interrogation, the trans-
ponder mode switch must
be
held in the TEST position.
4.2.6 Power Supply
The voltage regulator accepts
input
voltages
of
10.8 - 32.2 V and provides stabi lized voltages
of+
5 V and
+ 6.3 V. The
output
of
the voltage regulator
is
a\so
applied
to
the voltage transformer which provides
voltage
of
-
12
V,
+ 1 0 V and + 1500 V.
4-7
The document reference is online, please check the correspondence between the online documentation and the printed version.
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