Output Adjustments; Normal Monitor Calibration - HP 652A Operating And Service Manual

Section V
5-36.

Output Adjustments.

5-37. Amplitude Adjustment.
a . Connect 652A to ac voltmeter, as shown in Figure
5-2.
b. Set 652A controls as follows:
FREQUENCY RANGE . . . . . . . . . . . . . . XIO
FREQUENCY dial . . . . . . . . . . . . . . . . . . . . I
OUTPUT ATTENUATOR . . . . . . . . . . 3.0 V
AMPLITUDE . . . . . . . . . . . . . Fully Clockwise
c. AC Voltmeter should indicate at least 3 . 1 6 V rms. If
maximum output is less than 3.16 V, slightly decrease value
of A2R24*.
5-38. Waveform Adjustment.
n
a. Connect a 50 load to a 652A 50
terminal, and connect the output to an oscilloscope.
b. Set OUTPUT ATTENUATOR to 3.0 V, and turn
OUTPUT AMPLITUDE and VERNIER controls fully coun­
terclockwise.
c. Check 652A output with and without load on all
frequencies for spurious oscillations. Spurious oscillations
most likely occur in the output amplifier. A slight increase
in the value of A2R29 should eliminate this. If spurious
oscillations still occur, then change the value of A2C21
slightly. (If A2C21 is changed, then recheck I MHz
Frequency Calibration, Paragr aph 5·33.)
d. Since there is a· direct interaction between Wavefonn
Adjustment and Amplitude Adjustment, recheck Ampli­
tude Adjustment.
5�39. Minimu m Distortion Adjustment.
a. Connect 652A to distortion analyzer as shown in
Figure 5·5.
b. Set 652A controls as follows:
FREQUENCY RANGE . . . . . . . . . . . . . . XI K
FREQUENCY dial . . . . . . . . . . . . . . . . . . . . I
OUTPUT ATTENUATOR . . . . . . . . . . 3.0 V
OUTPUT AMPLITUDE
and VERNIER . . . . . . . . . . Fully clockwise
c. Adjust A2RI7 for minimum distortion as indicated
on distortion analyzer. Distortion should be less than 1 %
(40 d B down).
NOTE
Distortion will be typically 50 dB down.
5 - 1 4

5-40. Normal Monitor Calibration.

The following adjustments are critical. Final
voltage, measurements must be made with all
instrument covers in place.
a. Connect 652A to ac voltmeter as shown in Figure
5-2.
b. Set 652A controls as follows:
FREQUENCY RANGE . . . . . . . . . . . . . XI 00
FREQUENCY dial . . . . . . . . . . . . . . . . . . . . 4
OUTPUT AMPLITUDE . . . . . . . . . . . . 3.0 V
OUTPUT MONITOR . . . . . . . . . . . . NORMAL
c. Set OUTPUT AMPLITUDE and VERNIER controls
n
output
for a 3.0 V rms indication on ac voltmeter.
d. Adjust A l R23 for a 3.0 V indication on 652A
monitor. If AI R23 does not have sufficient range to
properly calibrate monitor, change value of Al Rn*.
(Increasing A l R22 * increases monitor indication and vice
versa.)
e. Set 652A FREQUENCY RANGE to XIM, and
FREQUENCY dial to 1 0.
f.
Set 652A OUTPUT AMPLITUDE and VERNIER
controls for a 3.0 V rms indication on ac voltmeter.
g. Making all o wance for any error of the ac voltmeter at
1 0 MHz, adjust A I C l 5 for a 3.0 V indication on 652A
If
monitor. necessary, change value of A2C25*.
If ac voltmeter error at 1 0 MHz is not known,
f ollow this
b.
Perform Steps a through d .
i . Connect equipment a s shown i n Figure 5-3 and adjust
reference supply for null indication on null meter.
j. Set 652A FREQUENCY RANGE to X I M and FRE­
QUENCY dial to 1 0.
k. Adjust 652A OUTPUT AMPLITUDE and VERNIER
controls for null indication on null meter. Do not readjust
reference supply.
I. Adjust AICI 5 for 3.0 V indication on 652A monitor.
NOTE
NOTE
alternative procedure.
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