Calibration—492/492P Service Vol. 1 (SN B030000 & up)
Performance Check
If the instrument has Option 03 (phaselock) the 1 kHz
resolution bandwidth is utilized. Proceed with the following:
1) decrease the RESOLUTION BANDWIDTH and FREQ
SPAN/DIV to 1 kHz and re-establish a signal reference level
as described previously;
2) check the -80 to -9 0 dBm gain accuracies by repeating
the process previously described;
3) the remaining 10 dB of gain range cannot be checked
accurately because of baseline noise. It is, however, directly
related to the -70 dBm to -80 dBm check.
6. Check Display Accuracy and Range
(8 0 d B in
10 dB /D IV m o d e with a n a c c u ra c y o f 1 d B / 1 0 d B to a
m ax im um cu m u lativ e e rro r o f ± 2 .0 d B o v e r t h e 8 0 d B
w ind o w ; 16 d B in 2 dB /D IV m o d e w ith a n a c c u r a c y o f
0 .4 dB /2 d B to a m a x im u m c u m ula tiv e e rro r o f
± 1.0 d B o v e r th e 16 d B w in d o w ; Lin m o d e is ± 5 % o f
full scale)
a. Test equipment setup is shown in Fig. 3-3. Apply
+ 10 dBm signal through external attenuators set to 0 dB to
the RF INPUT. Set the front-panel controls as follows:
REF LEVEL
MIN RF ATTEN
Video Filter
Vertical Display
FREQ SPAN/DIV
+ 10 dBm
OdB
NARROW
10 dB/DIV
10 MHz
RESOLUTION BANDWIDTH 1 MHz
b. Tune the FREQUENCY to center the applied signal on
screen. Reduce the FREQ SPAN/DIV and RESOLUTION
BANDWIDTH to 10 kHz. Carefully adjust the generator out
put so the signal level is at the top graticule line.
f. Return the external attenuation to 0 dB. Change the
Vertical Display to LIN. Adjust the signal generator output
for a full screen display.
g. Add 6 dB of external attenuation. Note that the signal
amplitude decreases half screen to 4, ± 0.4 divisions.
h. Add an additional 6 dB of attenuation. Note signal
amplitude decreases to 2, ±0.4 divisions or half amplitude.
i. Add another 6 dB of attenuation. Signal amplitude
should decrease to 1.0, ±0.4 divisions.
j. Return the Vertical Display to 10 dB/DIV and discon
nect the signal to the RF Input.
7. Amplitude Variation with Change in Resolution
Bandwidth
( < 0 . 5 dB )
a. Apply the calibrator signal to the RF INPUT and set
the front-panel controls as follows:
FREQUENCY RANGE 0—4.2 GHz
Option 01)
FREQUENCY 200 MHz
FREQ SPAN/DIV 20 MHz
RESOLUTION BANDWIDTH 1 MHz
Vertical Display 2 dB/DIV
REF LEVEL -2 0 dBm
MIN RF ATTEN 0 dB
PEAK/AVERAGE AVERAGE
(0—1.8 GHz
c. Add external attenuation in 10 dB steps for a total of
80 dB and note that the signal steps down screen in 10 dB
(±1.0dB) steps. Maximum cumulative error should not ex
ceed 2.0 dB over the display window.
d. Return the external attenuation to 0 dB and change
the Vertical Display to 2 dB/DIV. Set the FREQ SPAN/DIV
to 20 kHz and the RESOLUTION BANDWIDTH to 100 kHz.
Adjust the signal amplitude to the top graticule line with the
generator output control.
e. Repeat the procedure to check the accuracy of the
2 dB steps by adding external attenuation in 2 dB steps for
a total of 16dB. Deviation should not exceed
±0.4 dB/2 dB. Maximum cumulative deviation should not
exceed ± 1.0 dB over the 16 dB window.
NOTE
If digital storage is used, the PEAK/AVERAGE control
must be in the AVERAGE mode to measure ampli
tudes o f the 1 MHz, 100 kHz, and 10 kHz resolution
bandwidths and in the PEAK mode to measure the
amplitude of the 1 kHz and 100 Hz bandwidths.
b. Tune the 200 MHz calibrator marker to center screen
and reduce the FREQ SPAN/DIV to 500 kHz. Activate the
FINE REFERENCE LEVEL function and adjust the REF
LEVEL for a signal amplitude of six divisions.
c. Change the RESOLUTION BANDWIDTH to 100 kHz
and the FREQ SPAN/DIV to 100 kHz. Check that the ampli
tude change is not more than 0.5 dB.
3-14
REV JUN 1982
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