Modulation Adjustment | Agilent Technologies 33120A guide

Chapter 4 Calibration Procedures

Modulation Adjustment

Modulation Adjustment

The function generator stores three calibration constants related to amplitude modulation depth. The constants are calculated from the adjustment value entered. If the calibration procedure is aborted before all setup steps have been completed, no calibration constants are stored.

1Use a DMM to measure the function generator ACrms output voltage for each setup in the following table. These adjustments use a HIGH Z output termination.

	Nominal Output
SETUP	FREQUENCY	AMPLITUDE	Adjustment for:

30	1 kHz	3.5 Vrms	0% modulation depth.
31	1 kHz	0.707 Vrms	50% modulation depth.

32	1 kHz	6.36 Vrms	100% modulation depth.

2Use the CALIBRATE menu to adjust the displayed amplitude at each setup to match the measured amplitude and enter the value.

3Perform the AM Modulation Depth Verification procedures on page 61.

NEW CALIBRATION: A new calibration (SETUP 85 – Rev 4.0) has been added to eliminate a small residual error in the AM amplitude system which could potentially cause a failure of the AM amplitude verification. The new calibration operates just like the other AM calibrations (SETUP 30, 31, 32) in that the external measurement is AC Vrms with no load. The new calibration is not allowed until the other AM gain calibrations (SETUP 30, 31, 32) are performed.

The new algorithm is designed such that the calibration should not be required again once the function generator has been calibrated at the factory. However, if you change any critical analog components which determine amplitude in AM modulation, you should perform the calibration again.

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Agilent Technologies 33120A manual Modulation Adjustment, Frequency Amplitude

Contents

Service Guide Agilent 33120A MHz Function Arbitrary Waveform GeneratorPage Convenient bench-top features Flexible system features Front Panel at a Glance Front-Panel Number Entry Front-Panel Menu at a Glance MODulation Menu Display Annunciators Trig Rear Panel at a Glance Use the front-panel Input / Output Menu to This Book Page Contents Contents Replaceable Parts ServiceSchematics Contents Specifications Waveforms Modulation Characteristics General Specifications Product Dimensions Page Quick Start Quick Start To prepare the function generator for use One User’s Guide 〈 This Service GuideConnect the power cord and turn on the function generator Check the list of supplied items Verify that the power-line fuse is good Verify that there is ac power to the function generatorVerify the power-line voltage setting If the function generator does not turn on Remove the power cord . Remove To adjust the carrying handle Enter the magnitude of the desired frequency To cancel the number mode, press Shift CancelTo set the output frequency Set the units to the desired value To set the output amplitude Enter the magnitude of the desired amplitude To set a dc offset voltage How to change the offset to -1.5 mVdcEnable the offset modify mode Enter the magnitude of the desired offset Enter the desired duty cycle To set the duty cycleSelect the square wave function Output the waveform with the displayed duty cycle Move across to the Exprise choice To output a stored arbitrary waveformDisplay the list of arbitrary waveforms Select and output the displayed arbitrary waveform To output a dc voltage Enter the magnitude of the desired voltage To store the instrument state Set up the function generator to the desired configurationTurn on the state storage mode Save the instrument state Restore the instrument state Recall the stored instrument state To rack mount the function generator Quick Start Front-Panel Menu Operation Front-Panel Menu Operation Front-panel menu reference MODulation Menu Front-panel menu reference SYStem Menu Front-panel menu tutorial Messages Displayed During Menu Use Move across to the SYS Menu choice on this level Move across to the Power on command on this levelTurn on the menu Save the change and turn off the menu Cycle the power to restore the default valuesMove down a level to the Parameter choices Select amplitude adjustment Increment the first digit until 300.0 mVPP is displayed Move down a level and then across to the High Z choice Move down a level to the OUT Term commandTo select the output termination Use the menu to select the shape of the modulating waveform To output a modulated waveformSelect AM Set the modulation depth to 80% Move down a level verify that Sine is selectedSet the modulating frequency to 200 Hz Move across to the CAL Menu choice on this level Move down a level to the Secured commandTo unsecure the function generator for calibration Move down to the parameters level Calibration Procedures Calibration Procedures Time Required for Calibration Agilent Calibration ServicesCalibration Interval Automating Calibration Procedures Recommended Test Equipment Test Considerations Performance Verification Tests Self-Test Quick Performance Check Frequency Verification Function Gain and Linearity Verification DC Function Offset Verification AC Amplitude Verification AC Amplitude Verification Vrms 0.00035 Vrms Amplitude Flatness Verification 15.00 MHz AM Modulation Depth Verification Vrms 0.0061 Vrms Optional Performance Verification Tests Square Wave Duty Cycle Verification Distortion Verification Calibration Security Code Characters To Unsecure the Function Generator Without the Security Code Calibration Count Calibration Message Begin the Frequency and Burst Rate adjustment procedure General Calibration/Adjustment ProcedureMove down a level to the Unsecured command Move across to the Calibrate choice Perform the next adjustment procedure Calculate and save the new value Frequency and Burst Rate Adjustment Aborting a Calibration in Progress Function Gain and Linearity Adjustment AC Amplitude Adjustment High-Z AC Amplitude Adjustment High-Z Modulation Adjustment Frequency Amplitude AC Amplitude Adjustment 50W AC Amplitude Adjustment 50W Adjustment for KHz DC Output Adjustment Setup Duty Cycle Adjustment AC Amplitude Flatness Adjustment AC Amplitude Flatness Adjustment Exiting Output Amplifier Adjustment Optional Self-Test Error Messages Error MessagesSystem Error Messages Calibration Error Messages Theory of Operation Self-test procedures are described in chapter Theory of Operation Block Diagram Overview This discussion pertains to the block diagram shown on Block 8 on block diagram page 129 Schematic on Output Attenuator Block 7 on block diagram page 129 Schematic on Output Amplifier 740 R710 R717 740 R710 R711 R715 R716 R719 R720 AM Modulation Pre-attenuator Block 6 on block diagram page 129 Schematic onBlock 6 on block diagram page 129, schematic on Square Wave and Sync Square Wave and Sync Block 5 on block diagram page 129 Schematic on Filters Block 4 on block diagram page 129 Schematic on Waveform DAC/Amplitude Leveling/Waveform RAM Waveform DAC/Amplitude Leveling/Waveform RAM Block 2 on block diagram page 129 Schematic on Direct Digital Synthesis DDS Asic Block 3 on block diagram page 129 Schematic on System DACs Block 1 on block diagram page 129 Schematic on Floating Logic Block 10 on block diagram page 129 Schematic on Power SuppliesBlock 9 on block diagram page 129 Schematic on Earth-Referenced Logic Power Supplies See Block 11 on block diagram page 129 Schematic onDisplay and Keyboard Service Service See To prepare the function generator for use on Operating ChecklistIs the function generator inoperative? Does the function generator fail self-test? Types of Service Available Call 1-877-447-7278 and ask for Agilent Express Agilent suggests that you always insure shipments CleaningRepackaging for Shipment Electrostatic Discharge ESD Precautions Surface Mount Repair To Replace the Power-Line Fuse To Replace the Output Protection Fuse F801 Unit is Inoperative Troubleshooting HintsUnit Reports Error Unit Fails Self-Test Power Supply Problems Self-Test Procedures Power-On Self-Test 625 112 Replaceable Parts Replaceable Parts Main PC Assembly 116 117 118 119 120 121 122 123 Display and Keyboard PC Assembly 33120A Mainframe Manufacturer’s List Schematics8 Schematics Block Diagram Pull Off Handle Loosen Captive Sheet 1 132 Sheet 3 Sheet 4 Waveform DAC Schematic 134 Sheet 5 136 Sheet 7 Sheet 8 Output Attenuator Schematic 138 Sheet 9 of 10 Earth Reference Logic Schematic Sheet 10 Power Supplies Schematic 140 Sheet 1 of 1 Display and Keyboard Schematic TOP Side 33120-66521 REV a TOP Side 33120-66502 REV C Manual Part Number