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Section
III
GENERAL OPERATING INFORMATION
Model 3580A
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3-2
LOG
Markings
:
In
the
LOG
10 dB mode, these markings
indicate
signal amplitude in
dB below
full scale.
Frequency Markings: These markings indicate 20 Hz, 200 Hz,
2 kHz and 20 kHz decade frequencies of log sweep.
(Pa
ragraph
3-125)
CRT Display:
(Paragraph 3-158)
LIN
Markings: In Phe LIN
mode, these markings indica
t
e
signal
amplitude
in
percent
of
full
scale
'(1.0 =
100%
,
0.4 = 40%, etc.).
FREQUENCY
Dial:
Indicates start or center frequency of
linear or manual
sweep.
(Paragraph
3_gg)
START/CTR
Switch
:
When
set to START position, FRE-
QUENCY
dial
indicates start frequency of linear or manual
sweep;
when
set
to
CTR
position,
FREQUENCY dial indicates
center frequency of
linear
or manual sweeps. (Paragraph 3-100)
FREQUENCY Control
:
Tunes frequency of instrument over
0 Hz to 50
Hz
range. Is used to set start or center frequency of
linear or
manual
sweeps.
Push in
for coarse tuning; pull out for
fine tuning.
(Paragraph
3-96)
ZERO CAL
Potentiometer:
Used to calibrate FREQUENCY
dial for linear
or manual sweeps and to set the correct starting
point
for
log
sweep.
(Paragraph
3-102)
BANDWIDTH
Control: Controls 3
dB
bandwidth of IF Filter.
Is used to select
the
desired
frequency resolution
.
The six
BANDWIDTH settings
are
:
300
Hz,
100 Hz
,
30 Hz, 10 Hz,
3
Hz and 1 Hz. (Paragraph
3-80)
FREQ
SPAN Control:
Determines
width of spectrum to be
observed
.
Span
settings range from 5 Hz per division (50 Hz) to
5 kHz
per division
(50 kHz).
(Paragraph
3-103)
DISPLAY SMOOTHING Switch: Provides
three levels of noise
filtering for
video presentation.
ADJUST Indicator:
Lights to
indicate
that sweep rate is too
fast.
Will
go out when SWEEP TIME is increased, BAND-
WIDTH
is widened or when
FREQUENCY
SPAN is narrowed
.
(Paragraph
3-137)
SWEEP MODE
Switch
:
Permits
selection of six sweep modes
:
REP
(Repetitive).
SING
(Single),
RESET, MAN (Manual),
LOG ZERO
and LOG
.
(Paragraph
3-113)
MANUAL
VERNIER:
Tunes analyzer frequency and positions
horizontal
trace when SWEEP MODE switch is set to MAN
position. (Paragraph
3-121)
SWEEP
TIME
Control: Sets duration of single and repetitive
sweeps
.
Settings range from 0.01 second per division (O.l sec.)
to 200 seconds
per
division (2,000 sec.).
(Paragraph
3-133)
INPUT
Connector
:
Accepts
male, banana-plug connector
;
in-
put impedance
is 1 megohm, 30 pF
.
(Paragraph 3-13)
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OVERLOAD Indicator: Lights
to indicate
that input signal
exceeds m
ax
imum input level set by INPUT SENSITIVITY
and amplitude VERNIER controls. (Paragraph 3-37)
Amplitude VERNIER
:
For absolu
t
e measurements VERNIER
mu st
be
set
to
CAL
(fully
CW)
position
.
For
relative
measurements, VERNIER adjusts gain of analyzer to establish
a full-scale reference. As the VERNIER is rotated counter-
cl
o
ckwise, the gain decreases and the full-scale input level
increases.
(Paragraph 3-36, 3 -39)
INPUT SENSITIVITY Switch:
Selects
maximum (full scale)
input level and measurement range. F
o
r absolute measure-
ments,
full-s
c
ale
settings
range
from
+ 30 dBV
/
dBm
to
- 70 dBV
/
dBm
in
Log 10 dB mode or from
20 V
rms to
0
.2
mV rms in the Linear mode
.
In the Linear mode, seven
additional ranges (0.1 mV to 0.1
µ
V) can be selected by the
AMPLITUDE
REF LEVEL switch (Paragraph 3-39, 3-53 and
3-68)
.
With
the
switch
in the CAL position, the INPUT
t
e
rminal
s
are
disco
nnected and an internally generated calibra-
tion signal is applied to the input circuits (Paragraph 3-
7
7)
.
CAL 10 kHz Potentiometer: Adjusts gain of amplitude circuits
to
compensate for slight variations in amplitude accuracy
caused
by
temperature
changes
or
changes
i
n bandwidth
(Paragraph
3
-199).
dBV
/
LIN - dBm Switch: Set to
dBV/
LIN position for mea-
surements in dBV or rms volts; set to dBm 600 OHM position
for measurements in dBm 600 ohms. For measurements in
dBm
/
600
o
hms, an external termination
is
required.
AMPLITUDE REF LEVEL Switch
:
Operates in conjunction
with
INPUT
SENSITIVITY
switch
to
establish
full-scale
sensitivity and measurement range. In Linear mode it controls
the
IF attenuation. When rotated in a clockwise
direction,
full-scale
sensitivity
increases
in
a
20 V,
10 V,
2 V,
1 V
sequence (Paragraph 3-55). In the Log 10 dB mode, changing
the Amplitude Ref Level setting offsets the entire display in
10 dB increments (Paragraph 3-69). In Log 1 dB mode, the
Amplitude Ref Level control offsets the display to select any
10 dB portion of the 80 dB range (Paragraph 3-
7
1).
L
O
G 1 dB Button: (push to set; push LIN or LOG 10 dB to
release) Selects L
o
g 1 dB amplitude mode. Display sensitivity is
1 dB per division; display range is 10 dB. Any 10 dB portion of
the 80 dB range can be displayed by changing the
AMPLI
-
TUDE REF LEVEL setting. (Paragraph 3-71)
LOG 10 dB Button
:
(push to set; push LIN or
LOG
1 dB to
r
elease)
Selects
Log
10 dB
amplitude
mode
for
absolute
m easurements
i
n dBV or dBm/600 ohms or relative measure·
ments in dB
.
Display sensitivity is 10 dB per division; display
range is 80 dB
.
(Pa
r
agraph 3-66)
Figure
3-1. Front
Panel.
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