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Model 0663A
Service
SERVICE SHEET 13
A5A4 FRACTIONAL-N LOOP
REFERENCE BLOCK DIAGRAM 4
Table 4-l. Recommended Performance Tests
After Adjustments or Repaks
Table 5-2.. Post-Repair Adjustment Procedures
PRINCIPLES OF OPERATION
General
The Reference Divider divides the 10 MHz reference signal down to 100
kHz which is used as the reference signal to the phaxe detector.
This assembly also generates the sample pulse signal that clocks the
sample-hold circuit at the propep time.
Shaper
The shaper network consists of a diode'clamping network and a
differential amplifier. It provides the analog-to-TTL conversion.
Reference Divider
Ul and U4 form the divide-by-100 circuit which divides the 10 MHz
input signal to ppoduce the 100 kHz phase detector reference signal.
Sample Pulse Generator
The function of the sample pulse generator is to produce a 500 ns
pulse that is delayed by 1 microsecond from the leading ed,ge of the
phase detector reference signal. This is accomplished by detecting a
state in the divide-by-100 circuit which corresponds to the desired
delay time.
8-401/402