HP 8563A Service Manual

Also see for 8563A: Operating note

• 25. Press [AUX CTRl I, and and remove the divided-down 600 MHzinput to the phase/frequency detector by removing C519 from X501.26. Check that the voltage on A15J502 pin 3 is approximately 7 V.27. Replace C519 in X501.28. IT the loop is locked, the voltage on A15J502 pin 3 should be between 0 V and +5.75 Vde.29. IT the front panel CAL OUTPUT amplitude is out of specification and cannot be broughtwithin specification by adjusting A15R561, CAL AMPTD, check the calibrator automaticgain controller (AGC) amplifier with the following steps. Refer to function block Wof A15 RF Schematic (sheet 3 of 4) in the HP8560A/8561B/8563A Component LevelInformation binder.Note--••30.31.32.33.The 300 MHz CAL OUTPUT signal comes from the divided-down 600 MHz,which is passed through a leveling loop. The 300 MHz signal passes througha low-pass filter for reducing higher harmonics. These harmonics can fool thedetector. The 300 MHz signal passes through a variable attenuator controlledby PIN diode CR503 which is controlled by the feedback loop. Diode CR504is the detector diode (the same type as CR505). Diode CR504 providestemperature compensation between the reference voltage and the detected RFvoltage.a. Measure the level of 300 MHz at A15TP505 with an active-probe/spectrum-analyzercombination. IT the signal is less than +2 dBm, repeat the first 29 steps of thisprocedure .• IT the signal at this point is correct, place a short across the PIN diode CR503.• IT the signal level at the CAL OUTPUT is still less than -10 dBm with CR503shorted out, troubleshoot the RF forward path through amplifier Q505.• IT the CAL OUTPUT signal level is greater than -10 dBm, troubleshoot the PINdiode attenuator, the detector, or the feedback path.Measure the detector voltage at A15J502 pin 14. The voltage should measureapproximately +0.3 V de when the CAL OUTPUT signal is at -10 dBm. This voltageshould change with adjustment of AI5R561, CAL AMPTD.Check that the voltage at U507A pin 3 is + 1.7 V dc. If this voltage is not correct, theremay be a problem with the +10 V reference.Measure voltage at U507B pin 5 while adjusting R561. This is the temperature-compensated adjustable voltage reference to which the detected voltage is compared. Itshould vary between + 1.3 V and -0.6 V.Adjust R561 to its limits and verify that the output U507B pin 7 measures approximately+9 V dc at one limit and -12 V dc at the other limit .Synthesizer Section 10-45