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10. Step Gain and 18.4 MHz Local Oscillator Adjustments
A4A5
STEP GAIN
R2
Cl0
FREO
R51
+lOV
ADJ
RlO
ZERO COARSE
C9
“R
A4A5
Figure 3-49.
Location of
.l
dB
Gain Step, 18.4 MHz LO, and +
1OV
Adjustments
36. Key in
[FREQUENCY SPAN] 1 kHz,
[REs]
100 Hz, and
[PEAK SEARCH]
a].
37. Adjust front-panel FREQ ZERO control fully clockwise. Press
CPEAK
SEARCH]. Signal should move at least 60 Hz away from
center CRT graticule line.
38. Adjust front-panel FREQ ZERO control fully counterclockwise.
Press [PEAK XEARCH]. Signal should move at least 60 Hz away from
center CRT graticule line.
39. If proper indications are not achieved, increase or decrease
value of
A4A5C9
and repeat adjustment from step 33. Refer to
Table
3-3 for range of values.
40. Press [INSTR PRESET) and
IRECALL)
@.
41. Adjust front panel FREQ ZERO to peak the signal trace on the
CRT.
+
1OV
Temperature Compensation Supply Adjustment
42. Connect DVM to A4A5TPl (+
1OVF).
43. If DVM indication is between
+9
V dc and 10.0 V dc, no
adjustment is required.
44. If DVM indication is not within tolerance of step 43, adjust
A4A5R2
+
1OV
ADJ for DVM indication of
+9.5
ItO.
V dc at
normal room temperature of approximately
25°C.
Voltage change
is approximately 30
mV/OC.
Therefore, if room temperature is
higher or lower than
25OC,
adjustment should be made higher or
lower, accordingly.
Adjustments 3-91