TM 11-5840-281-35/1
ing of 60 FILL-IN control R1113 and 35 FILLIN control
the input to the E-reference supply is the -35 volts from
R1110. The glidepath data is then applied to the fill-in
Radar Receiver-Transmitter RT-818/ TPN-18 -35v
sawtooth generator as the fill-in angle no. 1 input. For
voltage regulator subassembly via relay Kl108 on the
the NORM mode of operation, the fill-in angle data is
chassis of Pulse Generator 0-1333/TPN-18. The -35
applied directly to the sawtooth generator subassembly.
volts is used directly as the E-reference while the +35
In the 35 EL and 60 AZ operation modes, the angle
volts is locked to the -35 volts by means of the voltage
data is attenuated by controls R1113 and R1110. The
regulator consisting of transistors Q2911, Q2912, and
voltage from the wiper arm of control R1113 is applied to
Q2913 on the cursor generator subassembly. Transistor
the sawtooth generator subassembly for 60 AZ
Q2911 serves as the error amplifier, transistor Q2912
operation, and from the wiper arm of control R1110 for
the regulator driver, and transistor Q2913 the series
350 EL operation.
regulator. The output of the +E reference regulator is not
(5) TOUCHDOWN 1 and TOUCHDOWN 2
adjustable but remains fixed at approximately +31 volts.
f. Artificial Angle Voltage Circuit (fig. 7-13). The
controls R1124 and R1125 are used in the glidepath
control circuit to establish a dc reference level for the
artificial angle voltage circuit consists of ART EL CAL
cursor trigger generator sawtooth baseline.
These
control R1101, ART AZ CAL control R1103, ART ANGLE
variable resistors compensate for the distance between
V control R1102, and ANGLE VOLTS switch S1103.
the runway touchdown point and Radar Set AN/TPN-18.
This circuit is used for alignment of the azimuth and
d. Height-Finder Control Circuit (fig. 7-13 and 7-
elevation cursor by substituting calibrated variable
56). The height-finder cursor is basically a 0-degree
voltages for the az-el angle volts. ANGLE VOLTS switch
glidepath cursor with an offset proportional to a particular
S1103 is used to select either simulated elevation angle
altitude. With EL CURSOR switch 51105 in the HF
volts or simulated azimuth angle volts and to energize
position, Antenna AS-1291/ TPN-8 angle voltage at the
relays which establish the proper circuit paths for
junction of resistors R9712 and R9713 is applied to the
application of the data to the courseline, glidepath, and
cursor angle no.
1 input of the cursor sawtooth
height-finder control circuits.
generator subassembly. The offset voltage to the cursor
sawtooth comparator circuit is provided by ALTITUDE
2-11.
Indicator Circuit Description
control R1122 located on the front panel of Pulse
(fig. 7-14)
Generator O-1333/TPN-18. ALTITUDE control R1122 is
mechanically coupled to the ALTITUDE indicator on the
a. General. The indicator circuits function as
Pulse Generator O-1333/TPN-18 front panel. When
part of the control-indicator section, and apply the signals
properly calibrated by HF CAL controls R1134 and
received from the range mark, sweep generator, cursor
R1141, ALTITUDE control R1122 applies a voltage to
control, and antenna control and data sections to the crt,
offset current regulator transistor Q2704 on the sawtooth
and to the deflection coils for the crt display. These
comparator subassembly proportional to the altitude
signals include the composite video consisting of video,
displayed on the ALTITUDE indicator. The configuration
range marks, touchdown marker, and cursor control
of the height-finder fill-in circuit is identical to the
pulse, the intensity gate and the horizontal deflection
glidepath circuit except for input. With EL CURSOR
voltages.
switch S1105 in the HF position, the input to the fill-in
(1) The step-sawtooth signal from the
circuit is the az-el angle volts appearing at the emitter of
sweep generator in the sweep generating subsection is
transistor Q9706 on the cursor control subassembly.
applied to the rotating-coil amplifier in the indicator
e. E-Reference Voltage Supply (fig. 7-13 and
subsection.
A feedback loop causes the current
7-57). The purpose of the +E and -E reference voltages
waveform through the deflection coils to have the same
is to reflect any variations in the voltages supplied to the
shape as the input sweep voltage waveform and
azimuth and elevation angle data potentiometers on the
compensates for any distortion introduced by the
antenna to the cursor generating circuits. The E-
inductance of the coils.
reference voltage regulator is located on the cursor
(2) The positive output step-sawtooth of the
generator subassembly. With TRIGGER switch S2201
sweep generating subsection of the rotating coil amplifier
on the trigger delay generator subassembly in the EXT
passes through the deflection coil, producing linear
position,
increasing magnetic fields which
2-47
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