TM 11-6625-2781-14&P-2
Section III
SECTION III
OPERATION
3-11.
The display group enables the operator to
3-1. INTRODUCTION
calibrate the display and to select a variety of scan and
display conditions. The controls are explained in Figure
3-2.
This section provides complete operating
3-1. However, there is
one analyzer characteristic that
instructions for the HP 8553B Spectrum Analyzer RF
an operator should consider when he is using an
Section. It also provides a brief description of IF
externally generated scan (and MANUAL SCAN in the
Section and Display Section controls; for a detailed
8552B). The DISPLAY UNCAL lamp only responds to
description of these sections, refer to their manuals.
the analyzer's control settings, not to the signal itself.
So the lamp will not indicate that an external sweep is
3-3. CONTROLS, INDICATORS AND CONNECTORS
too fast, causing the display to become uncalibrated.
3-4. The RF Section is used with either an 8552A or
3-12. Frequency. The frequency group consists of:
8552B IF Section and one of the 140 series display
FREQUENCY
sections. The instruments shown in Figure 3-1 are,
FINE TUNE
SCAN WIDTH
respectively, an 8553B RF Section with an 8552A IF
STABILIZER
RANGE MHz
Section and a 140T Display Section, and an 8553B RF
Section with an 8552B IF Section and a 141T Display
3-13. The frequency group enables the operator to
Section. The rear panel of the instrument shown in
control how the analyzer samples the frequency domain.
The SCAN WIDTH controls permit the operator to look
section.
at a spectrum that varies in width from 0 100 MHz to
ZERO. FREQUENCY and FINE TUNE set the center
3-5. OPERATOR'S CHECKS
frequency of the spectrum, and BANDWIDTH controls
the resolution of the signals seen on the CRT.
3-6. Upon receipt of the analyzer, or when one or more
sections are changed, perform the operational
3-14. Amplitude. The amplitude group consists of:
This procedure
corrects for minor differences between units and
LOG REF LEVEL LINEAR SENSITIVITY
ensures that the RF section, IF section and display
LOG/LINEAR
section are properly matched.
INPUT ATTENUATION
3-7. OPERATING CONSIDERATIONS
3-15. The amplitude group enables the operator to
measure signal amplitude in voltage or dBm. INPUT
3-8. Control Grouping
analyzer's input mixer.* For minimum distortion and
3-9. The analyzer front panel controls fall into three
maximum dynamic range, always set it for -40 dBm at
general groups: those that deal with the display, those
the mixer.
For example, initially set INPUT
that deal with frequency, and those that deal with
ATTENUATION at 20 dB or more (this ensures that any
amplitude.
signal that is less than 1V rms is below compression).
Then note the highest level signal on the display, and
3-10. Display. The display group consists of:
subtract that reading from 40 dB; set INPUT
ATTENUATION for the result. (If the signal is about -10
SCAN TIME
BASE LINE
dBm, 40 dB -10 dB = 30 dB; set the attenuator for 30
CLIPPER SCAN MODE
INTENSITY
dB.)
SCAN TRIGGER
FOCUS DISPLAY
ADJUST
AMPL CAL
VIDEO FILTER
In addition, MANUAL SCAN on the 8552B and the
variable persistence and storage controls on the 141T
*Signal level at input mixer =
Signal level at RF INPUT - INPUT ATTENUATION
3-1