TM 11-5840-281-35/1
measurements as specified in paragraph 3-12
3-13.
Waveforms
above.
a. Normal waveforms present at significant points in
major components of Radar Set AN/TPN-18 are shown
d. When a waveform at a particular point is observed
in figures 3-1 through 3-15. The waveforms shown were
to be abnormal, the cause may be the absence of a
taken with Oscilloscope AN/USM-140B. Detailed
signal from another component. The point at which to
instructions for operating the AN/USM-140B are
start checking waveforms is at the component input
contained in TM 11-6625-535-15-1.
trigger jack.
b. Before comparing the waveforms obtained on the
oscilloscope with normal waveforms as shown in the
3-14. Timing Chart
illustrations, carefully read the notes on the waveform
illustrations and exactly duplicate the conditions under
A timing chart is provided in figure 3-16 for Radar Set
which the normal waveforms were obtained. If an
AN/TPN-18. The timing chart illustrates the time
observed waveform does not closely resemble the
relationship of significant trigger and gating pulses
normal waveform, trouble is indicated.
utilized in Radar Set AN/TPN-18. All trigger and gating
pulses are synchronized with either the system pre-
c. A departure from the normal waveform indicates
trigger generated in the radar transmitter or by the iff pre-
trouble between the point at which the waveform is
trigger from an associated iff equipment. System timing
observed to be normal and the point at which the
is synchronized to the radar transmitter system pre-
waveform is observed to be abnormal. For example, if a
trigger when Radar Set AN/TPN-18 is operated
waveform is observed to be normal at the input of a
independent of an iff equipment. When operated with an
iff equipment, system timing is synchronized with iff
stage and abnormal at the output of the same stage, it is
equipment developed pre- triggers of either 400 or 1200
an indication that the trouble is in that stage. When
pps. The 1200 pps iff pre-trigger is utilized in all search
trouble is indicated in a stage, take voltage and
ranges up to 40 miles. The 400 pps iff pre-trigger is
utilized in the 80-mile search range.
SECTION III. ADJUSTMENT AND ALIGNMENT PROCEDURES
c. Procedure.
3-15. General
(1) Adjust three jackscrews in legs of Antenna
This section contains the procedures required for
Pedestal AB-738/TPN-8 until bubble level MP548 on
alignment and adjustment of Radar Set AN/TPN-18 on a
elevation Antenna Drive TG-114/TPN-8 indicates level
system basis. The test equipment required for the
(bubble is in exact center of circle).
alignment and adjustment procedures is given at the
(2) Attach clinometer to clinometer mount on
beginning of each paragraph in addition to equipment
azimuth Antenna AS-1292/TPN-8.
conditions and control settings.
(3) On master Control-Indicator C-6988/TPN-18,
place ANTENNA (servo) switch to U or D as required to
position azimuth Antenna AS-1292/TPN-8 at 0 degree as
a. Test Equipment Required. Clinometer MP3502.
indicated on clinometer.
b. Equipment Conditions.
(4) Rotate azimuth Antenna AS-1292/TPN-8 360
(1) Radar Set AN/TPN-18 turned on.
degrees by hand, observing clinometer at each 90-
(2) On Radar Receiver-Transmitter RT-818/TPN-
degree point.
18 control panel, SCAN and HV switches placed to OFF.
(5) Make minor adjustments in three
(3) On master Control-Indicator C-6988/TPN-18,
Antenna Pedestal AB-738'TPN-8 jackscrews as required
SCAN MODE switch placed to SEARCH, SCAN switch
until all 90-degree points observed in step (4) above
OFF, and TRANSMITTER switch OFF.
indicate 0 degree on clinometer.
3-25
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