equal to peak-to-peak amplitude of noise on remainder
of oscilloscope trace.
(b) Rf power switch: POWER OUT.
(11) On video amplifier, adjust WP BAL
(c) PULSE LENGTH: 10.
control R1416 cw until noise baseline during canceled
(d) PULSE DELAY: 40.
pulse time are even (level with baseline of entire trace)
(c) OUTPUT ATTEN.: 20.
with noise on remainder of oscilloscope trace.
(3) On oscilloscope, place controls to
(12) On master Control-Indicator C-6988/
positions indicated in (a) through (k) below.
(a) SWEEP MODE: PRESENT.
not through NARROW to HV ON. Observe that HV ON
(b) TRIGGER SOURCE: EXT AC.
indicator is extinguished.
(c) HORIZONTAL DISPLAY: X10.
(13) On video amplifier, adjust NP BAL ADJ
(d) EXTERNAL VERNIER: CAL.
control R1411 until noise baseline during pulse time is
(e) SWEEP TIME (MILLISECONDS/
even (level with baseline of entire trace) with noise on
remainder of oscilloscope trace.
(f) SWEEP TIME VERNIER: as
(14) On radar test set, adjust OUTPUT
ATTEN. control between mds level and mds plus 50 dbm
(g) Vertical Presentation: CHANNEL
level (indicated value on OUTPUT ATTEN. dial at mds
level minus 50), while observing cancelled pulse on
(h) CHANNEL A AC-DC: DC.
oscilloscope. Baseline of cancelled pulse should remain
at same approximate level over this 50-db range as
remainder of baseline. Make minor adjustment of NP
(j) CHANNEL A SENSITIVITY VER-
BAL ADJ R1411, as required, to minimize shift in
NIER: As required.
baseline of cancelled pulse over this range.
(k) CHANNEL A POLARITY: +UP.
(15) On master Control-Indicator C-6988/
(4) On radar test set, adjust OUTPUT
going through WIDE to HV ON. Observe that HV ON
displayed on oscilloscope is approximately one-half of
indicator is extinguished.
limiting level (any usable amplitude well below limiting
(16) On radar test set, adjust OUTPUT
ATTEN. control between mds level and mds level plus
(5) On radar test set, adjust RF TUNING
50 dbm level, while observing cancelled pulse on
control for maximum amplitude of pulse displayed on
Adjust OUTPUT ATTEN. control to
constant. Make minor adjustment of WP BAL R1416, as
increase attenuation as required to prevent limiting.
required, to minimize shift in baseline of cancelled pulse.
(6) Disconnect CHANNEL A INPUT test
(17) On video amplifier, rotate CLIP ADJ
prod from DET VIDEO testpoint TP301 on Inter- mediate
control R1423 cw until negative-going noise is clipped
Frequency Amplifier AM3339/TPN-8 and connect to FTC
without reduction of positive-going noise amplitude.
VIDEO testpont TP703 on video amplifier.
(18) Disconnect oscilloscope and radar test
(7) On master Control-Indicator C-6988/
TPN-18, place FTC switch to ON.
(8) On video amplifier, rotate CLIP ADJ
control R1423 and NP BAL ADJ control R1411 fully ccw.
(9) On radar test set, rotate OUTPUT
Do not replace covers on Radar Receiver-
Transmitter RT-818/TPN-18 until alignments and
adjustments are completed.
discernible signal (mds)).
(10) On radar test set, rotate OUTPUT
ATTEN. control to reduce attenuation until peak-to-peak
noise amplitude during pulse time is