HP 8555A Operating And Service Manual page 29

Model8555A
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G)
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Plus "+" lights when logarithmic amplification
(11)
is
selected; times "x" lights when linear
amplification (11) is selected. With "+" lighted,
LOG REF line is sum (black numerals) of LOG
REF LEVEL controls). With "x" lighted, per
division absolute voltage amplitude is product of
blue numeral LINEAR SENSITIVITY control
settings .
Provides a 30-MHz signal at -30 dBm for amplitude
calibration of spectrum analyzer.
Indicates 1 dB increments for logarithmic ampli-
fication; indicates multiplication factors up to
unity for linear amplification.
Provides pen lift operation to HP 7005, 7035,
7004, 7034 and all new TTL compatible
HP
recorders. Provides input for external blanking sig-
nal (-1.5V) for external scan mode operation. Pro-
vides input for external positive or negative trigger
pulses (2-20V), normally negative, polarity selected
by internal switch in IF Section) for external scan
trigger operation.
Detected video output proportional to vertical
deflection on CRT.
For receiving an external scan ramp or output
coupling for the internally-generated scan ramp.
Input or output function determined by !NT/EXT
positions of SCAN MODE switch.
Adjusts vertical position and gain of trace.
Adjusts horizontal position and gain of trace.
Selects scan trigger mode.
Selects 10 dB logarithmic or linear display mode in
8552A plus another 2 dB log position in 8552B.
The dB graduation (black numerals), opposite the
lighted index lamp, indicate the power level at the
LOG REF graticule line on CRT when LOG/
LINEAR (11) is set to LOG. With LOG/LINEAR
set to LINEAR, the voltage graduations (blue
numerals), opposite the lighted index lamp, indi-
cate the per division multiplier for calibrated
voltage amplitude.
Selects scan ramp mode. Ramp is internally
generated for SINGLE/IN'!' positions but it must
be externally supplied for EXT position. (Refer to
Item 7). Model 8552B has an added manual scan
mode position. (Refer to Item 34.)
Controls SCAN TIME PER DIVISION.
Press to initiate scan with SCAN MODE switch set
to SINGLE. Press during scan to stop and reset
scan.
Selects 100 Hz, 10 kHz or OFF position of
lowPass filter for detected video in 8552A plus an
added 10 Hz in 8552B.
Lights for duration of each scan for single and
internal scan modes.
Operation
4T)
Blanks lower part of trace to prevent over·
exposure of photographs due to high intensity of
baseline. Blanking function also prevents blooming
with a variable-persistence storage display section.
Provides 1- and 10-volt, peak-to-peak, 60 Hz
squarewave outputs. '
These calibrated outputs should never be
used with the spectrum analyzer. (These
outputs are for use only with the 1400-
series oscilloscope plug-ins.)
Excessive brightness for a static or very
slow-moving trace may burn the
phosphor and permanently damage the
CRT. This caution is applicable to both
the fixed and variable-persistence/storage
CRT; however, the latter is especially
vulnerable to operational errors of this
type .
Makes base line parallel with the horizontal grati-
cule line.
Focuses CRT beam .
Used with FOCUS control (22) to obtain smallest
spot with maximum roundness.
Lights when line voltage is applied and instrument
is turned on .
Switches line voltage to instrument.
When used with 1400-series oscilloscope plug-ins,
intensifies and returns beam to CRT, regardless of
deflection potentials. Produces no effect on analy-
zer displays.
G
Display CRT with graticule lines.
e
Selects
non-stora§If.~~]
Use storage function when possible to
prevent damage to the CRT.
6)
Press to ERASE when in S'l'D or F AS'!' writing
speed.
I)
Selects writing speed.
0
Varies time the trace is visible.
t)
Selects storage time.
G
Press to store signal display. Storage time (relative
display brightne&s) in storage mode is adjusted by
(32).
C)
Manual scan control positions the electron beam
on CRT when using MAN SCAN mode.
Figure 3-2. Typical Display and IF Section Controls, Connectors and Indicators ( cont'd)
3-7