HP 8560E Service Manual

Chapter 10 549
Synthesizer Section
Unlocked Fractional N PLL
A15 RF assembly.
3. Change the spectrum analyzer from the fractional N span to 0 Hz.
4. Check the frequency at A14TP1. It should equal the value found by
pressing
CAL, MORE 1 OF 2, FREQ DIAGNOSE, and RAW OSC FREQ.
5. Check the tune voltage at the ungrounded end of C135.
6. Look up the expected problem area in Table 10-12 on page 549 with
the information from steps 4 and 5. Go to the appropriate
troubleshooting steps.
Table 10-12 Unlocked Fractional N Troubleshooting Areas (08560-60069 and
Above)
Measured VCO
Frequency
Relative to
Expected Value
Tune Voltage
Less than
−4 V
About
−3.3 V
Between
−2 V and
+10 V
About
+11 V
Greater
than
+12.5 V
Measured >
expected
VCO clamp VCO Divider or
integrator
Divider or
integrator
VCO clamp
Measured <
expected
VCO clamp Divider or
integrator
Divider or
integrator
VCO VCO clamp
Measured, not
oscillating
VCO clamp VCO VCO VCO VCO clamp
Table 10-13 Unlocked Fractional N Troubleshooting Areas (08560-60062 and
below)
MeasuredVCO
Frequency
Relative to
Expected
Value
Tune Voltage
Less
than
−12.5 V
About
−11 V
Between
±10 V
About
+11 V
Greater
than+12.5
V
Measured >
expected
VCO
clamp
VCO Divideror
integrator
Divideror
integrator
VCO clamp
Measured <
expected
VCO
clamp
Divideror
integrator
Divideror
integrator
VCO VCO clamp
Measured, not
oscillating
VCO
clamp
VCO VCO VCO VCO clamp

HP 8560E Specifications

General

Brand	HP
Model	8560E
Category	Measuring Instruments
Language	English