HP 8663A manual Service Sheet A5A4 FRACTIONAL-N Loop Referenceblock Diagram

Model 0663A Service

SERVICE SHEET 13

A5A4 FRACTIONAL-N LOOP

REFERENCEBLOCK 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.

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