Calibration—492/492P Service Vol. 1 (SN B030000 & up)
Performance Check
I. Tune the 492/492P FREQUENCY to 3.0 GHz. Apply a
cw marker of 3.0 GHz to the 492/492P input. Re-establish a
signal amplitude of approximately half screen. Switch the
Marker Sweeper on, then sweep the 2.5 to 3.5 GHz portion
of band 2 .
m. Check and note the frequency response of this
portion.
n. Increase the center FREQUENCY to 4.0 GHz and the
sweep generator span range from 3.5 to 4.5 GHz. Check
the next segment of the band 2 range.
Part 3
Procedure for Instruments with Preselector (Option 01)
a. Test equipment setup is the same as the Part 1 pro
cedure (Figs. 3-4 through 3-6). Set the front-panel controls
as follows:
FREQUENCY RANGE
FREQUENCY
FREQ SPAN/DIV
MIN RF ATTEN
REF LEVEL
AUTO RESOLUTION
TIME/DIV
Vertical Display
Band 1 (0—1.8 GHz)
5 MHz
1 MHz
30 dB
0 dBm
On
2 0 ms
2 dB/DIV
o. Increase the sweep generator and 492/492P center
FREQUENCY to the next 1 GHz segment and check fre
quency response for the upper portion of band 2 .
p. Return the 492/492P FREQUENCY RANGE to band
1 and the FREQ SPAN/DIV to 200 MHz.
q. Using the above procedure, check the frequency re
sponse of the upper portion of band 1. (Image response for
band 1 is 4 GHz from the true signal; therefore, a wider
span can be used without interference from the image.)
r. Switch the 492/492P FREQUENCY RANGE to band 3
(3.0 to 7.1 GHz). Tune the center FREQUENCY to 3.5 GHz
and reduce the FREQ SPAN/DIV to 100 MHz. Set the
sweep generator for a sweep output from 3.0 to 4.0 GHz.
s. Repeat the procedure, in 1 GHz increments, to check
the frequency response for band 3, then check the remain
ing bands to 21.0 GHz. Frequency response in band 4
(7.1—18 GHz) is ±2.5 dB and ±3.5 dB for band 5
(15—21.0 GHz).
b. Apply the output of a constant level and calibrated
100 kHz to 10 MHz signal generator to the RF INPUT of the
492/492P. Set the generator frequency to 100 kHz and its
output for about — 10 dBm.
c. Adjust the REF LEVEL so the amplitude of the
100 kHz signal is about half screen, in the 2 dB/DIV mode.
d. Slowly tune the frequency of the signal generator
from 100 kHz to 10 MHz, monitoring the output to ensure it
remains constant. Note the frequency response (amplitude
deviation above and below the average). Frequency re
sponse or amplitude deviation must not exceed ± 1.5 dB.
(See Fig. 3-6 for the average level.)
e. Replace the 100 kHz to 10 MHz signal source with a
0.01 to 2.4 GHz sweep oscillator and connect the test
equipment as shown in Fig. 3-5. The output of the sweep
generator is applied through a 3 dB attenuator and high per
formance coaxial cable to a power divider. Connect one out
put of the power divider directly to the RF INPUT and the
other output to the sensor for the power meter.
t. Procedure for checking frequency response, when
using external mixers, is provided in the respective mixer
instruction sheet.
Part 2
Procedure for Instruments with Digital Storage
(Option 02)
The frequency response check for instruments with Digi
tal Storage is the same as the procedure for Part 1 with the
additional feature of a stored display. Activate VIEW B,
SAVE A, and MAX HOLD. This will provide a stored display
of the frequency response as the frequency range is swept.
Between steps, MAX HOLD must be deactivated and re
activated to clear storage for each sweep.
f. Change the FREQ SPAN/DIV to 200 MHz and tune
the FREQUENCY to approximately 1.0 GHz. On the sweep
generator, select a 1 GHz cw marker and adjust the output
for about — 6 dBm reading on the power meter. With the
492/492P Vertical Display in the 2 dB/DIV mode, adjust the
REF LEVEL so the signal amplitude is about half screen.
g. Change the sweep generator sweep mode to auto
matic internal sweep and set the sweep time to 1 0 0 s for its
slowest sweep time.
h. Check the frequency response as the sweep gener
ator scans across the 10 MHz to 2 GHz span. Deviation
must not exceed ± 1.5 dB. (See Fig. 3-6.)
3-18
REV AUG 1981
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