HP 654A - 5-62. Balance Adjustments

Model 654A
Section V
readings are low, proceed to step d. If all the
readings are within tolerances, proceed to step f.
d. Check readings at 1, 5 and 10 on the dial. If
readings are close to proper value, proceed to step
e. If they are not, perform the following:
1) Place dial to clockwise position.
2) Remove the frequency dial knob and loosen the
four dial retaining screws.
3) Slip the dial to read 1 with a counter indication
of 1 kHz ( Frequency Range 1 K).
4) Tighten the retaining screws and replace the
knob.
e. Set the FREQUENCY dial to 10. Adjust S2C2 and
S2C8 alternately until the counter indicates a
frequency of 10 kHz and A2TP2 voltage is - 370
± 10 mV. Then recheck at 1 on the dial. Work
back and forth between 1 and 10 on the dial until
both are near or within the allowed limits. Recheck
step c.
1) If S2C2 does not have sufficient range, change
the value of S2C3* ( refer to Table 5-5). If S2C8
does not have sufficient range, change S2C9*.
2) If A2TP2 should not remain - 370 mV
± 20 mV over the entire dial range, change
value of S2C16* or S2C13* to bring frequency
and A2TP2 voltage within limits.
f. Check all frequencies on the X1K range according
to Table 5-2. The voltage at 1 and 10 on the dial
should read the same ± 10 mV. If voltage is not
within limits, proceed to step e(2).
NOTE
Steps d, e and f interact with each other.
5-53. X100, X1K and X1OK RANGE TRACKING.
a. Connect the equipment as shown in Figure 5-15.
Set the 654A controls as in Paragraph 5-50b.
b. Check frequency tracking of the FREQUENCY
dial using the settings and tolerances given in Table
5-2 for the X100, X1K and X1OK ranges. Also
monitor A2TP2 voltage which should remain
within - 0.3 to - 0.4 V over the entiry range. If
necessary, pad S2C17* for X100 RANGE and
S2C1* and S2C18* for X1OK RANGE for correct
frequency and A2TP2 voltage when the dial is set
to 10.
5-54. X10 RANGE ADJUSTMENTS.
a. Connect the equipment as shown in Figure 5-15.
b. Set the 654A FREQUENCY RANGE switch to
X10 and FREQUENCY dial to 1, other controls as
in Paragraph 5-50b. The counter ( set to read
• period average) should indicate 100 ± 3 msec ( 10
± 0.3 Hz) and A2TP2 voltage should be - 370
• ± 40 mV; if either frequency or A2TP2 voltage is
not within tolerance, change the value of S2R2*
and S2R10* simultaneously ( see Table 54) until
the tolerances are met.
c. Check frequency tracking using the settings and
tolerances given in Table 5-2 for the X10 range.
Monitor A2TP2 voltage which should remain at
- 370 ± 40 mV over the entire range. If necessary,
to make dial track, repeat step b but set the
frequency towards the upper or lower tolerance.
5-55. X1M RANGE ADJUSTMENTS.
a. Connect the equipment as shown in Figure 5-15.
b. Set the 654A FREQUENCY RANGE switch to
X1M and the FREQUENCY dial to 10, other
controls as in Paragraph 5-50b.
NOTE
Adjust A2C1, S2C6 and S2C12, if
necessary, to start oscillation.
c. Adjust S2C6 and S2C12 ( see Table 54) for a
counter indication between 10.1 and 10.2 MHz ( 1
to 2% high) and A2TP2 voltage between - 0.38 V
and - 0.40 V.
d. Set the FREQUENCY dial to 5; counter should
indicate 5,000 +/- 65kHz. If not, perform the
following.
1) Note whether the counter indication is higher
or lower than 5,000kHz.
2) Set the FREQUENCY dial to 10; if the
frequency of step 1) was high, adjust A2C1 to
increase the counter indication slightly; if the
frequency of step 1) was low, adjust A2C1 to
slightly lower the counter indication.
NOTE
While making this adjustment to A2C1,
the oscillator may stop oscillating;
however, the adjustment to be made in
step 3) will start oscillations again.
3) Readjust S2C6 and S2C12 as in step 5-55c.
5-15