TB 9-6625-1138-24
8. Frequency Accuracy and Stability
a. Performance Check
(1) Connect frequency counter to TI OUTPUT using voltage divider.
(2) Position controls as listed in (a) through (c) below:
(a) MODE SELECTOR switch to BFO.
(b) RANGE (VOLTS) switch to 1 V.
(c) FREQUENCY dial to 20 Hz. If frequency counter does not indicate
between 39 and 67 ms, perform b (1) below.
(3) Vary autotransformer output between 105 and 125 V ac. Frequency counter will
remain between 39 and 67 ms.
(4) Adjust autotransformer output for 115 V ac.
does not indicate within limits specified, perform b (2) below.
Table 3. Frequency Accuracy
Test instrument
Frequency counter indications
FREQUENCY dial setting
Min
Max
(Hz)
30
28.329
ms
40.486
ms
40
22.026
ms
28.902
ms
50
18.018
ms
22.472
ms
60
15.244
ms
18.382
ms
60
13.210
ms
15.552
ms
80
11.655
ms
13.477
ms
90
10.428
ms
11.891
ms
100
9.4340
ms
10.638
ms
400
2.4450
ms
2.5575
ms
700
1.4045
ms
1.4535
ms
1,000
0.98522
ms
1.01523
ms
4,000
3,955 Hz
4,045 Hz
7,000
6,925 Hz
7,075 Hz
10,000
9,895 Hz
10,105 Hz
20,000
19,795 Hz
20,205 Hz
30,000
29,695 Hz
30,305 Hz
40,000
39,595 Hz
40,405 Hz
50,000
49,495 Hz
50,505 Hz
(6) Substitute frequency counter with multimeter.
(7) Vary FREQUENCY dial from 20 Hz to 50 kHz. If multimeter does not indicate
at least 1 V, perform b (3) below.
b. Adjustments (fig. 2)
(1) Adjust L6 for out-of-tolerance indications on low end of FREQUENCY dial (R).
