HUNT GENERATOR MODULE A8400.

TM 11-5820-670-30

1-39. HUNT GENERATOR MODULE A8400.

EL1AT112

The manner in which the hunt generator controls master oscillator frequency drift is discussed in

paragraph 1-34. The following information covers operation of its subassemblies.

When the master oscillator frequency shifts beyond the correcting range of the phase discriminator,

the bias voltage from the hunt cutoff detector in module A4200 is removed, causing the sawtooth gate

to stop conducting.

When sawtooth gate Q8403 stops conducting, the voltages applied to sawtooth generator Q8402

increase causing the 100 Hz sawtooth voltage to be generated.

The 100 Hz voltage is applied through isolation amplifier Q8401 and the low-pass filter to the master

oscillator for frequency correction. Once the master oscillator frequency is brought into the correcting

range of the phase discriminator, the hunt cutoff bias voltage from A4200 is then reapplied, turning on

Q8403. When Q8403 is on, no sawtooth voltage in Q8402 is generated.

Isolation amplifier Q8401 isolates the sawtooth generator from the phase discriminator. The low-pass

filter attenuates frequencies above 11.5 MHz and prevents generation of spurious signals in the

frequency control loop.

1-39