HUNT DISCRIMINATOR, PHASE DISCRIMINATOR; REFERENCE OSCILLATOR-WORKING EXAMPLE

TM 11-5820-670-30

1-18. CRS HUNT DISCRIMINATOR A3600, CRS PHASE DISCRIMINATOR A3700, AND REFERENCE

OSCILLATOR A2000. (CONT)

With the radio set to 30.00 MHz, the 5.65 MHz crystal is selected, causing the reference oscillator to

output a 5.65 MHz fixed frequency. Since the reference oscillator and limiter output frequencies are

the same, the phase discriminator does not output a dc voltage to the damping network. Therefore,

no dc voltage will be present at TP3001 due to the phase discriminator action.

In actual operation even with the local oscillator almost perfectly alined, a slight plus or minus dc

voltage is present at TP3001. Its presence is due to normal imbalances in the hunt discriminator and

phase discriminator circuits.

HUNT DISCRIMINATOR, PHASE DISCRIMINATOR; REFERENCE OSCILLATOR-WORKING EXAMPLE

LOCAL OSCILLATOR RUNNING TOO HIGH

E L 1AT096

Assume the radio is set to 30.00 MHz and the local oscillator is misalined, thereby causing it to

operate at 41.550 MHz. The output of the limiter, 5.70 MHz, is 50 kHz higher than it would be if the

oscillator were exactly on frequency.

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