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Adjustment Procedures
2715 Spectrum Analyzer Service Manual
5-19
17. Adjust the Low Frequency VCO and High Frequency VCO as follows:
a. Enable the LFVCO adjustment procedure by pressing UTIL5240;
then follow screen prompts up to the adjustment of R746.
b. After adjusting R746, press the BKSP oncetoreturntoCFCV1
ADJUSTMENTS menu; then press 1 for the HFVCO adjustment and
follow screen prompts.
NOTE. Capacitor C611 is adjusted for 8.5 V at the second peak as C611 is
adjusted from fully clockwise.
c. After adjusting C611, press BKSP to return to CFCV1 ADJUSTMENTS
menu; then press 3 for the FM DAC sensitivity adjustment and follow
screen prompts.
18. Adjust the Counter Level as follows:
a. Recall factory default power up settings by pressing UTlL 1 1.
b. Disable frequency corrections by pressing UTIL435. Press any menu
button to exit the menu.
c. Enable continuous strobes by pressing UTIL5166. Press any menu
button to exit the menu.
d. Set SPAN/DIV to MAX SPAN and press SWEEP ↓ twice.
e. Use a X10 probe to connect the Channel 1 input (X channel input for an
X-Y display) of the test oscilloscope to TP2 on the Sweep board (See
Figure 5--1). Ground the test oscilloscope at the Spectrum Analyzer
chassis.
f. Use a X1 probe to connect the Y channel of the test oscilloscope to the
center of R620 (CNT LVL) on the Phase Lock CFC assembly.
g. Set the X input deflection factor at 0.2 V/div and the Y input deflection
factor at 10 mV, AC coupled. Set the test oscilloscope Time/Div control
to X-Y.
h. Adjust R620 (CNT LVL) on the Phase Lock CFC assembly for an
envelope waveform amplitude of 80 mVp-p. Check that the ratio of the
peak-to-peak to valley-to-valley amplitude is less than 2:1.
i. Recall factory default power up settings by pressing UTlL 1 1.
j. Remove the probes from the instrument.
k. Perform frequency normalizations by pressing UTIL31W.