can be adjusted, and then return the FREQ SPAN/DIV to
MAX. Sweep the 3.0 to 7.1 GHz frequency range of band 3,
checking frequency response. It may be necessary to check
frequency response in smaller segments, with PEAKING
adjusted for the shorter spans, if the response does not
meet the ±2.5 dB specification.
Calibration—492/492P Service Vol. 1 (SN B030000 & up)
Performance Check
n. Repeat the foregoing procedure to check the re
sponse of the remaining bands to 21 GHz. Frequency re
sponse for band 4 (5.4—18 GHz) is ±3.5 dB and ±5.0 dB
for band 5 (15.0—21.0 GHz).
Part 4
Procedure for Instruments with Preselector and Digital
Storage (Options 01 and 02)
The procedure is the same as the procedure in Part 3
with the additional feature of storage. Activate VIEW B,
SAVE A, MAX HOLD and deactivate VIEW A. MAX HOLD
must be reactivated for each sweep to update data stored
for each sweep.
9. Check Preselector Ultimate Rejection
(Option 01)
a. Apply a 3.5 GHz, —30 dBm, signal from a signal gen
erator to the RF INPUT. Set the front-panel controls as
follows:
FREQUENCY RANGE
FREQ SPAN/DIV
AUTO RESOLUTION
Vertical Display
REF LEVEL
MIN RF ATTEN
TIME/DIV
Digital Storage (Option 02)
Video Filter
Band 2 (1.7—5.5 GHz)
1 MHz
On
10 dB/DIV
—30 dBm
OdB
AUTO
VIEW A/VIEW B
WIDE
b. Tune the FREQUENCY to center the 3.5 GHz signal
on screen and then reduce the FREQ SPAN/DIV to 10 kHz.
Keep the signal centered on screen as the span is reduced.
Adjust the signal generator output for a full screen display,
adjusting PEAKING to maximize the signal amplitude.
c. Change the FREQUENCY to band 3 (3.0—7.1 GHz).
d. Check for any spurious response on the display. Any
signal feedthrough must be down 70 dB or more from the
level established in part b of this step. If this condition is not
met, it is a good indication the YIG-tuned filter should be
replaced.
10. Check Frequency Span/Div Accuracy (± 5% of
the selected span/div)
Span accuracy is checked by noting the displacement of
calibrated markers from their respective graticule line over
the center eight divisions of the screen. Range is in a 5-10-
2 0 sequence and depends on the frequency band and op
tion as shown in Table 3-5. The frequency span/div
accuracy is checked for all FREQ SPAN/DIV settings on
band 1 and at 500 MHz/Div on band 4.
Table 3-5
NARROW AND WIDE SPANS vs FREQUENCY BAND
Narrow Span Wide Span
Band
Standard
Option 03
All Instruments
1—3
10 kHz/Div
500 Hz/Div 200 MHz/Div
4—5
50 kHzDiv 500 Hz/Div 500 MHz/Div
6 50 kHz/Div 500 Hz/Div
1 GHz/Div
7—8
100 kHzDiv 500 Hz/Div 2 GHz/Div
9 200 kHz/Div 500 Hz/Div
2 GHz/Div
1 0 500 kHz/Div 500 Hz/Div
5 GHz/Div
11 500 kHz/Div 500 Hz/Div
10 GHz/Div
Accuracy: Within 5% of selected span/Div over center 8 divi
sions of display
a. Set the front-panel controls as follows:
FREQUENCY RANGE 0—4.2 GHz (0—1.8 GHz
Option 01)
RESOLUTION BANDWIDTH 1 MHz
FREQ SPAN/DIV 200 MHz
TIME/DIV .1 s
Vertical Display 10 dB/DIV
REF LEVEL -3 0 dBm
MIN RF ATTEN 0 dB
Digital Storage (Option 02) VIEW A/VIEW B
b. Connect the CAL OUT to the RF INPUT and adjust
the FREQUENCY to align the 100 MHz markers so the
200 MHz/div accuracy can be measured over the center
eight divisions of the display (two markers per division). It
may be necessary to change the REF LEVEL to obtain ade
quate markers. Maximum deviation must not exceed
10 MHz/div (0.25 minor divisions).
c. Change the FREQ SPAN/DIV to 100 MHz and check
the span/div accuracy. Error must not exceed 5% of the
span/div or 5 MHz/div.
3-20
REV FEB 1982
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