TM 11-5840-281-35/1
Figure 2-1. Radar Set AN/TPN-18, block diagram
Antenna AS-1292/TPN-8 scans a 60-degree sector,
i.
During SEARCH mode, the range marks
elevation Antenna AS-1291/TPN-8 scans as 11-degree
on the ppi display are blanked in the area corresponding
sector, and Control-Indicator C-6988/TPN-18 uses a
to the NORM mode (precision) scan sector. This aids the
beta scan. The SIMULT mode is used only when two
operator in directing the aircraft to the proper position so
Control-Indicators C-6988/TPN-18 are connected to
it will appear on the beta scan when NORM mode is
Radar Set AN/TPN-18. When SIMULT mode is selected,
selected.
azimuth Antenna AS-1292/TPN-8 rotates through 360-
j.
The height finding function provides a
degrees, elevation Antenna AS-1291/TPN-8 scans an
means of determining aircraft altitude on a precision
11-degree sector, and one Control-Indicator uses a ppi
approach by means of a movable cursor on the elevation
display while the other uses a beta scan. The azimuth
beta display. Altitude information is indicated on a
precision radar signal display for SIMULT mode is
calibrated counter, which is referenced either to sea level
provided by a 30-degree sector of the search scan. The
or to actual ground level.
ppi display has no radar video signals during this 30-
degree sector.
2-2.
Transmitter Section Description
(fig. 7-5)
h.
Radar signal information can be
a.
General. The transmitter section
displayed on Control-Indicator C-688/TPN-18 at ranges
consists of a trigger generator and shaper circuit, a
of 5, 10, 20, and 40 nautical miles in all operating modes
modulator circuit, a magnetron rf oscillator, a high
except IFF. The IFF mode and the ppi display range of
voltage power supply circuit, a high voltage regulator
80 nautical miles are provided for display of. iff
circuit, and an overload sensor circuit with associated
information only. Iff information can also be displayed in
protective circuitry.
all SEARCH mode ranges. Refer to paragraph 3-4 in TM
(1)
The trigger generator develops a
5840-281-12 for further information on modes of
negative pulse output at a nominal rate of 1200 pulses
operation.
per second (pps). These pulses are sent to the sensitivity
time control unit to the indicator sec-
2-2
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