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 theadjustment of R746.
b. After adjusting R746, press the BKSP oncetoreturntoCFCV1
ADJUSTMENTS menu; then press 1for the HFVCO adjustment and
follow screen prompts.
NOTE. Capacitor C611 is adjusted for 8.5 V at the secondpeak as C611 is
adjusted from fully clockwise.
c. After adjusting C611, press BKSP to returnto C FCV1 ADJUSTMENTS
menu; then press 3for the FM DAC sensitivity adjustmentand 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 correctionsby pressing UTIL435.Press an y menu
button to exit the menu.
c. Enable continuous strobes by pressing UTIL5166.Pres s any menu
button to exit the menu.
d. Set SPAN/DIV to MAX SPANand press SWEEP ↓twice.
e. Use a X10 probe to connect theC hannel1 input (X channel input for an
X-Y display) of the test oscilloscopeto 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 P haseLock C FC assembly.
g. Set the X input deflection factorat 0.2 V/div and the Y input deflection
factor at 10 mV, AC coupled. Set the test oscilloscope Time/Divcontrol
to X-Y.
h. Adjust R620 (CNT LVL)on the Phase Lock CFC assembly for an
envelope waveform amplitudeof 80 mVp-p. Check that the ratio of the
peak-to-peak to valley-to-valleyamplitude 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 frequencynormalizations by pressing UTIL31W.