Internal Modulation Oscillator Frequency Accuracy, Output Voltage, and Distortion

Calibration Procedure For Signal Generator, Sg1112Viu, Sg1112V2U, And Mis-28707Ty2 Page Navigation
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TB 9-4931-488-24

(3) Set MODULATION FREQUENCY range switch to X100 and adjust

MODULATION FREQUENCY vernier dial fully ccw.

(4) Connect true rms voltmeter INPUT to A11TP4 (fig. 3) and chassis ground.

Adjust A11R28 (fig. 3) for a 1.4 (1.37 to 1.48) V ac true rms voltmeter indication. Record

true rms voltmeter indication.

(5) Connect frequency counter CHANNEL A input to TI AM OUTPUT. Adjust

MODULATION FREQUENCY vernier dial fully cw.

(6) Adjust A11C2 and A11C3 (fig. 3) until true rms voltmeter indicates within

0.1 V ac of value recorded in (4) above.

NOTE

Adjusting A11C2 (fig. 3) ccw decreases voltage while increasing

frequency. Adjusting A11C3 (fig. 3) ccw increases both voltage

and frequency.

(7) Adjust MODULATION FREQUENCY vernier dial to 20. If frequency counter

does not indicate 2.00 0.02 kHz, adjust vernier dial for a 2.00 kHz frequency counter

indication. Loosen setscrews in vernier control shaft gear and position vernier dial to 20.

Tighten setscrews and, if necessary, readjust A11R28 (fig. 3) for true rms voltmeter

indication between 1.37 and 1.48 V ac. Record true rms voltmeter indication.

(8) Adjust MODULATION FREQUENCY vernier dial to 200. If true rms

voltmeter does not indicate within 0.01 V ac of value recorded in (7) and frequency counter

indication is not 20 0.2 kHz, readjust A11C2 (fig. 3) and A11C3 (fig. 3) for desired

indications.

(9) Adjust MODULATION FREQUENCY vernier dial to 20. If true rms voltmeter

does not indicate within 0.01 V ac of value recorded in (7) above and frequency counter

indication is not 2.00 0.02 kHz, repeat technique of (7) and (8) above.

(10) Adjust MODULATION FREQUENCY vernier dial to 20. True rms voltmeter

should indicate between 1.37 and 1.48 V ac. Record true rms voltmeter indication.

(11) While observing true rms voltmeter indication, slowly vary TI modulation

frequency from 2 kHz to 20 kHz. True rms voltmeter should indicate within 0.03 V ac of

indication recorded in (10) above.

(12) Set MODULATION FREQUENCY range switch to x3k and adjust

MODULATION FREQUENCY vernier dial to 200. Adjust A11C9 (fig. 3) for a 600 6 kHz

frequency counter indication.

(13) Position controls as listed in (a) through (c) below.

(a) FM switch to INT.

(b) MODULATION FREQUENCY range switch to x100.

(14) Connect true rms voltmeter INPUT to A11TP5 (AM OUT, fig. 3) and chassis

ground. Adjust A11R35 (fig. 3) for a 0.840 0.010 V ac true rms voltmeter indication.

Record true rms voltmeter indication.