Mhz Flatness Adjustment - HP 652A Operating And Service Manual

Model 652A
b. Set 652A FREQUENCY RANGE switch to XIM and
FREQUENCY dial to 1 0. If 652A does not oscillate, adjust
A2C5, S I CS and S I C I O .
c . Adjust A2C5 and S I C S alternately for 10.1 5 MHz
( 1 .5% high) as indicated on counter and for required
voltage on A2TP2 (within ± 0.02 V of reference voltage
recorded in Paragraph 5-30, Step
f requency and A2T P2 voltage cannot be obtained, change
the setting ofS1CIO and repeat this step.
d. Set FREQUENCY dial to 5 and note frequency ; if
not within tolerance (Table 5-1), perform the following:
1 . Set dial to 1 0 and slightly change setting of
S I CI O . (Example: If frequency is low with 5 set
on dial, adjust 81 CI 0 to slightly lower frequency
when dial is at 1 0 ; and vice versa.)
2. Readjust A2C5
1 0. 1 5 MHz and required A2TP2 voltage (same as
Step c).
3 . Set dial to 5 and note frequency; if still not
within tolerance, repeat Steps d-I , d-2, and d-3 as
often as necessary until tolerances are met at both
5 and 10 positions of FREQUENCY dial. If
necessary, change the value of S l CI 4 *.
e. Set FREQUENCY dial to 1 . Check that frequency
1)
(Table 5- and A2TP2 voltage (same as in Step c) are
within required tolerances; if either is not correct, change
value of RANGE switch resistors (Table 5-6) simultane­
ously until both frequency and voltage are within required
limits. If RANGE switch resistors are changed, it will be
necessary to repeat Steps c and d.
f.
Set FREQUENCY dial to 2; counter should indicate
2000 ± 60 kHz.
NOTE
to
It may b e necessary
high for the dial to track.
g. While monitoring the voltage at A2TP2, move the
dial through its range from 1 to 1 0 ; the A2TP2 voltage
must remain within the range: - 300 m V to - 450 m V. If
A2TP2 voltage exceeds these limits, then recalibrate using
Paragraph 5-33.
5-34. X 1 00K Range F r equency Calibration.
NOTE
The f ollowing adjustments are critical. For
each adjustment, remove cover and make the
adjustment; then replace cover before making
frequency or voltage checks. I f desired, Fi gure
5-10 gives a scaled drawing of top and bottom
fl. If the required
and SI C5 alternately for
set frequency about 1%
alignment access covers with cut-outs lhat will
allow adjustments while the covers are in
place. The dimensions are given in inches.
a. Connect equipment as shown in Figure 5-8.
b. Set FREQUENCY RANGE to X 1 00K and FRE­
QUENCY dial to 10. Adjust S I C4 and S I C9 simultaneously
for 1 MHz (See Table 5-1) as indicated on counter and for
required A2TP2 voltage (within ± 0.02 V of reference
voltage recorded in Paragraph 5-30, Step fl.
c. Set FREQUENCY dial to 1 . Counter should indicate
100 kHz (See Table 5-7) and A2TP2 voltage should be the
same as in Step b ; if either is not within tolerance, change
value of RANGE switch resistors (Table 5- 6) simultane­
ously until both frequency and voltage are within required
limits.
d. Repeat Step b.
e. Set FREQUENCY dial to 5 ; frequency should be
500 kHz (See Table 5-7) as indicated on counter and
A2TP2 voltage should be wi thin 40 m V of reference
voltage. If either is incorrect, repeat Steps b , c, and d until
both frequency and A2TP2 voltage are within tolerance.
(Remove test lead attached to A2TP2.)
5-35. 1 0 MHz F latness Adjustment.
a. Connect 652A to ac voltmeter as shown in Figure
5-2.
b. Set 652A controls as follows:
FREQUENCY RANGE . . . . . . . . . . . . . . Xl K
FREQUENCY dial . . . . . . . . . . . . . . . . . . 1 0
_
OUTPUT ATTENUATOR . . . . . . . . . . 3.0 V
OUTPUT MONITOR . . . . . . . .
c. Adjust 652A OUTPUT AMPLITUDE and VERNIER
controls for 3.0 V rms as indicated on ac voltmeter. Do not
readjust AMPLITUDE controls for remainder of this
paragraph.
d. Connect equipment as shown in Figure 5-3. Adjust
reference supply for null indication. Do not readjust
reference supply once null is obtained.
NOTE
Instrument covers must be in place.
e. Set 652A FREQUENCY RANGE to XIM. Sweep
FREQUENCY dial slowly from I to 1 0. Null meter
deviation from null should not exceed ± 0.54 mY.
f. Adjust A2Cl4 to reduce any output peaking. If
necessary, change value of A2C24- slightly.
Section V
. .NORMAL
_ _
5-1 3