TB 9 6625-357-24
Table 4. Low Pass Frequency Dial Accuracy
Test instrument
Frequency counter indications
CUTOFF FREQ Hz
LOW PASS
dial settings
switch settings
Initial
Final
Min
Max
22
X10K
22 kHz
220 kHz
198 kHz
242
kHz
180
X10K
180 kHz
1.8 MHz
1.62 MHz
1.98 MHz
20
X1K
2 kHz
20 kHz
19 kHz
21
kHz
60
X1K
6 kHz
60 kHz
57 kHz
63
kHz
200
X1K
20 kHz
200 kHz
190 kHz
210
kHz
200
X100
2 kHz
20 kHz
19 kHz
21
kHz
60
X100
600
Hz
6 kHz
5.7 kHz
6.3 kHz
20
X100
200
Hz
2 kHz
1.9 kHz
2.1 kHz
20
X1
10
Hz
20
Hz
47.619 ms
52.6316 ms
60
X1
30
Hz
60
Hz
15.873 ms
17.544 ms
200
X1
20
Hz
200
Hz
4.7619 ms
5.2632 ms
b. Adjustments
(1) Adjust P202 (fig. 1) until true rms voltmeter indicates 1 V (R).
(2) Adjust P204 (fig. 1) until true rms voltmeter indicates 1 V (R).
(3) Perform tracking check in table 3. If error exists and is constant, perform (a)
through (e) below. If error is not constant, perform (a) through (c) and (f) below.
(a) Set CUTOFF FREQ Hz dial to 60 and selector switch to LOW PASS X100.
amplitude for a 1 V indication on true rms voltmeter.
(c) Set selector switch to LOW PASS X10.
(d) Adjust CUTOFF FREQ Hz dial until true rms voltmeter indicates 0.708 V.
(e) Loosen and slip CUTOFF FREQ Hz dial until 60 is aligned with indicating
mark. Retighten dial.
(f) Adjust P205 (fig. 1) until true rms voltmeter indicates 0.708 V (R).
(5) Adjust C322 (fig. 3) until true rms voltmeter indicates 0.708 V (R).
7