TM 11-6625-2781-14&P-2
Section III
PRELIMINARY SETTINGS
13. Set SCAN WIDTH (inner/red) switch to PER
1.
Set to correspond with available input voltage.
DIVISION: set (outer/black) switch to provide
(The instrument is fused for 115-volt operation;
the necessary spectrum detail. (Select blue
if 230-volt power is used, refer to fuse
numbers to narrow the viewed spectrum; select
replacement procedures in manual on display
black numbers to widen the viewed spectrum.)
section mainframe.
14. Adjust coarse and fine FREQUENCY controls to
2.
Plug into power outlet; use ground adapter for
center the signal of interest.
electrical systems having no grounding wire.
15. Select BANDWISDTH compatible with input-
3.
Set to INT.
signal parameters, but not one which causes
4.
Connect 8553B Load Assembly A14.
DISPALY UNCAL to light.
5.
Set power switch to on (up); to be sure that ON
16. Use LOG REF LEVEL control to establish
lamp lights and fan operates.
calibrated power level of LOG REF line of
6.
Set INPUT ATTENUATION to 50 dB.
graticule. Read power level of signal directly by
7.
LOG REF LEVEL - LINEAR SENSITIVITY
adding power figure (dBm) opposite the lighted
controls: Rotate large control until one of the
index lamp to the difference between signal
peripheral black marks aligns with LOG NORM.
peak and LOG REF line. (Example: -50 dBm
Rotate
(venier)
small
knob
fully
opposite lighted index lamp and signal peak at
counterclockwise.
center graticule line of display, then
8.
Set:
signal power level = -50 + (-40)
VIDEO FILTER to OFF
= -90 dBm
SCAN MODE to INT
17. Set LOG/LINEAR switch to LINEAR. Use LOG
SCAN TRIGGER to AUTO
REF LEVEL to establish per-division linear
multipliers (V/DIV). If necessary, set venier
LOG/LINEAR to LOG
SCAN TIME PER DIVISION for viewing
control for sub-multiplier. Multiply number of
convenience
graticule divisions that enclose signal by
BASELINE CLIPPER fully ccw
selected multipliers. (Example: signal peak at
SCAN WIDTH (inner/red) to 0-100 MHz
center line of display graticule, 1 V/DIV
BANDWIDTH (300 kHz automatically selected
opposite lighted index lamp, and venier set to .5
for 0-100MHz scan)
- signal amplitude, reading from bottom of
TUNING STABILIZER to on (up)
graticule = 4 divisions x 1 V/DIV x .5 = 2 V).
RANGE-MHz to 0-110
9.
Adjust focus and INTENSITY for best resolution
DISPLAY CALIBRATIONN
of baseline trace.
18. Absolute amplitude calibration of the CRT
display is directly related to setting of the
SIGNAL CONNECTION & IDENTIFICATION
following controls: SCAN TIME PER DIVISION,
CAUTION
BANDWIDTH, SCAN WIDTH PER DIVISION
To avoid mixer burnout, attenuator
and the VIDEO FILTER. During operation, the
damage or both, the RF INPUT
settings of these controls are continually
should never exceed 104 Vac peak or
monitored and, if the combination of settings will
+50 Vdc.
not permit a calibrated display, the DISPLAY
UNCAL lamp lights. With the VIDEO FILTER
10. Connect any unknown signal within frequency
switch set to OFF, typical values for ON/OFF
range of 1 kHz to 110 MHz.
conditions of the DISPLAY UNCAL lamp are
11. Set INPUT ATTENUATION so that signal
given in Table 3-1. When the tables indicate
amplitude is adequate for viewing.
the DISPLAY UNCAL lamp to be " ff" it is
o ,
12. Tune with coarse FREQUENCY until negative
acceptable for the light to be " n" if the light
o
marker causes maximum " ip" in signal of
d
subsequently goes " ff" when either the SCAN
o
interest. Read frequency under red marker on
TIME PER DIVISION or the SCAN WIDTH PER
CENTER FREQUENCY MHz scale.
DIVIDION control is switched one position
EXPANDING SIGNAL FOR STUDY AND
counterclockwise.
MEASUREMENT
Figure 3-3. General Operating Procedures
3-8
