Calibration—492/492P Service Vol. 1 (SN B030000 & up)
Performance Check
c. Change the front-panel controls for:
FREQUENCY RANGE
1.7—5.5 GHz
FREQ SPAN/DIV
200 MHz
FREQUENCY
2.0 GHz
VIDEO FILTER
Off
PEAK/AVERAGE
Fully cw
d.
Type RUN and press RETURN on the controller. Line
1 1 0
of the program immediately sets the sweep and the
digital storage so you can change FREQUENCY and other
local controls as required for the TUNE check. Line 120 re
stores local control with the GTL message.
k. Disconnect the microwave comb generator and con
nect the output of the time mark generator to the RF INPUT.
Set the time mark generator for 1 ^s output.
I. Change the FREQUENCY (and REF LEVEL if neces
sary) while decreasing the FREQ SPAN/DIV to 100 kHz to
maintain a centered marker above the 0 Hz spurious
response.
m. Type 1M and press RETURN on the controller. Note
the difference in the displayed signals, then press RETURN
again.
e.
Center the marker while decreasing the FREQ
SPAN/DIV to 10 MHz. Adjust PEAKING as necessary and
set REFERENCE LEVEL to display the comb marker. For
non-Option 01 instruments, set the SPAN/DIV to 500 kHz
and use IDENTIFY to make sure the analyzer is centered on
a real signal, then return to 10 MHz/div.
n. Repeat part m seven times. Reset FREQUENCY after
noting the error if the accumulated TUNE error is great
enough to move the signal off screen. (The FREQUENCY
control is active at the point where you note the TUNE er
ror.) The largest error should not exceed 1.5 divisions
(150 kHz).
f.
Enter 500M (type 500M and press RETURN). If you
make an error in this procedure, press BREAK twice and
run the program again. If the 492P asserts SRQ (evident by
message on controller screen and S in 492P lower readout),
enter WBYTE @20: to clear the SRQ.
g.
The analyzer tunes 500 MHz, takes a single sweep,
and sets up a display of the marker signal you centered and
the signal acquired after the TUNE command executed.
Note the error between the two signals.
h.
Press RETURN to continue.
Change
FREQ
SPAN/DIV to 200 MHz and FREQUENCY to 3.0 GHz. Re
peat parts e through g, then repeat the procedure for a fre
quency of 4.5 GHz.
I. Tune error for the above checks should not exceed 3.5
divisions (7% of 500 MHz tune step is 35 MHz).
The foregoing procedure checks performance related to
the upper DAC of the 1 st LO center frequency control. The
remaining procedure checks the lower DAC for the 1 st LO.
j. Press RETURN and change the controls as follows:
FREQUENCY RANGE
0—4.2 GHz (0— 1
. 8
GHz,
Option 01)
FREQ SPAN/DIV
200 MHz
FREQUENCY
1 MHz
REF LEVEL
+30 dBm
This completes the check of TUNE command perfor
mance related to the 1 st LO. The following steps check the
upper DAC of the pair that control the 2nd LO center
frequency.
o.
Increase FREQ SPAN/DIV to 1 MHz and change
FREQUENCY to center a marker at least three divisions
away from the 0 Hz marker:
p. Decrease the span to 10 kHz/div keeping the marker
centered and change the time marker output to
1 0
με.
Change the REFERENCE LEVEL as necessary to keep the
marker above the noise.
q. Type 100K and press RETURN on the controller.
Note the difference in the displayed signals, then press RE
TURN again.
r. Increase span to 50 kHz/div, change the time marker
output to 1
ms
, and tune FREQUENCY two markers to the
left ( - 2 MHz). Repeat parts p and q.
s. Increase the span to 50 kHz/div, change the time
marker output to 1 ^s, and tune FREQUENCY four markers
to the right (+ 4 MHz). Repeat parts p and q.
t. The largest error noted should not exceed 0.7 division
(7% of 100 kHz tune or 7 kHz).
REV AUG 1981
3-9
