TB 9-6625-1356-24
h. (Hewlett-Packard, Model 651A) Turn adjustment screw approximately 15 degrees
ccw. If meter pointer moves, repeat g above and this step.
i. (All other models) insert pointed object into recess on adjustment wheel and rotate
wheel until meter pointer is exactly over 0.
j.
Set LINE switch to ON.
8. Frequency Accuracy and Stability
a. Performance Check
(1) Connect frequency counter to TI using a 50 feedthrough termination.
(2) Position controls as listed in (a) through (d) below:
FREQUENCY RANGE switch to X1K.
(a)
FREQUENCY dial to 1.
(b)
(Model 652A) OUTPUT MONITOR switch to NORMAL.
(c)
OUTPUT ATTENUATOR switch to 3.0 VOLTS.
(d)
(3) Adjust AMPLITUDE controls for a 3.0 V indication on TI meter. If frequency
counter does not indicate between 980 and 1020 Hz, perform b below.
(4) Vary autotransformer output from 105 to 125 V and back to 115 V. Frequency
counter indication will remain between 980 and 1020 Hz.
(5) Repeat technique of (3) above for FREQUENCY RANGE and FREQUENCY
dial settings listed in table 3. If frequency counter does not indicate within limits specified,
perform b below.
Table 3. Frequency Accuracy Check
Test instrument
Frequency counter indications
FREQUENCY RANGE
FREQUENCY dial
Min
Max
switch settings
settings
X10
1
9.70 Hz
10.30 Hz
X10
5
48.50 Hz
51.50 Hz
X10
10
97.00 Hz
103.00 Hz
X100
1
98.00 Hz
102.00 Hz
X100
5
490.00 Hz
510.00 Hz
X100
10
.980 kHz
1.02 kHz
X1K
5
4.90 kHz
5.10 kHz
X1K
10
9.80 kHz
10.20 kHz
X10K
10
98.00 kHz
102.00 kHz
X10K
5
49.00 kHz
51.00 kHz
X10K
1
9.80 kHz
10.20 kHz
X100K
1
98.00
kHz
102.00
kHz
X100K
5
490.00
kHz
510.00
kHz
X100K
10
0.98
MHz
1.02
MHz
X1M
10
9.70
MHz
10.30
MHz
X1M
5
4.85
MHz
5.15
MHz
X1M
1
0.97
MHz
1.03
MHz
