Maximum Carrier Set and Modulation Zero Set

TB 9-6625-1999-35

NOTE

Do not install RF oscillator-RF amplifier shield assembly until

directed.

12. Maximum Carrier Set and Modulation Zero Set

a. Performance Check

(1) Connect true rms voltmeter to RF OUTPUT 50Ω.

(2) Position controls as listed in (a) through (d) below:

(a) MODULATION SELECTOR switch to EXT. AC.

(b) ATTENUATOR switch to 1.0 VOLTS.

(d) ATTENUATOR VERNIER control for fully cw.

(3) Set frequency to 50 kHz and tune at a moderate speed over range to 170 kHz.

Tune frequency control over each band up to 10 MHz. If true rms voltmeter does not

indicate 1.05 V or greater throughout tuning range, perform b below.

(4) Set MODULATION SELECTOR switch to cw. If voltage indication on true

rms voltmeter changes, perform b below.

(5) Adjust MODULATOR AMPLITUDE control throughout range. If true rms

voltmeter indicates a voltage change, perform b below.

b. Adjustments

(1) Adjust output frequency to range and frequency having lowest output voltage.

(2) Set MODULATION SELECTOR switch to CW.

(3) Adjust MAX CARRIER SET R60 (fig. 1) for a 1.05 V indication on true

rms voltmeter.

(4) Set MODULATION SELECTOR switch to EXT. AC. If a voltage change is

indicated on true rms voltmeter, adjust MOD ZERO SET R69 (fig. 1) for a 1.05 V

indication on true rms voltmeter.

(5) Repeat a (3) and (4) above. If necessary, slightly readjust R60.

(6) Repeat (1) through (5) above until RF output is 1.05 V or greater over entire

frequency range and there is no change in output voltage when MODULATION

SELECTOR switch is set from EXT. AC to CW.

13. Modulation Meter Accuracy

a. Performance Check

(1) Connect RF OUTPUT 50 Ω to measuring receiver.

(2) Position controls as listed in (a) through (e) below: