Fm Accuracy And Fm Overmod Adjustment S-S3; Fm Accuracy And Fm Overmod Adjustment - HP 8340B Manual

5-9. FM ACCURACY AND FM OVERMOD ADJUSTMENT

Reference
Performance Test: FM
Service Section: Sweep Generator
Description
In the FM accuracy portion of this adjustment procedure, a synthesized function generator and is
used to FM the OUT at a fixed modulation rate and frequency deviation. The FM input signal is set
such that when the OUT's FM GAIN adjustment (FM accuracy) is adjusted properly, the power of the
OUT's carrier frequency will be nulled (minimum power level).
In the FM overmodulation adjustment portion of this adjustment, the OUT is initially set up for its
maximum frequency deviation and modulation rate. From this point, the rate is increased until the
OUT's FM circuitry reaches its maximum capability. The modulation rate is then decreased until the
circuitry stabilizes and the overmod adjustment is set to just turn on the OVERMOD annunciator.
OSCILLOSCOPE
HP 8340B/41B
Loop
— YO
Figure 5-26. FM Accuracy and Overmod Adjustment Setup
Adjustments 5-53