Fluke 5720A service manual 3911 A5/A6 Ampl. Control At 30MHz, 3912 A5/A6 Output Offset At 10MHz

5700A/5720A Series II Calibrator

Service Manual

level it is checked for 0.0V ±0.7V. A failure indicates the Wideband Output (A5) assembly is probably at fault.

3911 A5/A6: Ampl. Control At 30MHz

The Wideband assemblies are configured for a 3.5V and 1.2V output at 30.0 MHz. WB AMPLITUDE CONTROL which it the control signal to the Wideband Oscillator assembly is divided and connected to the SDL line for measurement by the adc circuit on the DAC assembly. At the 3.5V level it is checked to be 4.8V ±1.0V and at the 1.2V level it is checked for 0.0V ±0.8V. A failure indicates the Wideband Output (A5) assembly is probably at fault.

3912 A5/A6: Output Offset At 10MHz

The Wideband assemblies are configured to 3.5V at 1.3 MHz, 1.2V at 1.3 MHz, 2.0V at

3.0MHz, 1.0V at 4.1 MHz, 3.3V at 5.0 MHz, 2.0V at 6.0 MHz, 2.0V at 7.0 MHz, and 2.0V at 7.9 MHz. The output of the Unity Gain Amplifier circuit on the Wideband Output assembly is measured via the OUTPUT OFFSET line to ensure the dc offset is less than 20 mV. A failure indicates the Wideband Output (A5) assembly is probably at fault.

3913 A5/A6: Output Offset At 30MHz

The Wideband assemblies are configured to 3.5V at 30.0 MHz and 1.2V at 30.0 MHz. The output of the Unity Gain Amplifier circuit on the Wideband Output assembly is measured via the OUTPUT OFFSET line to ensure the dc offset is less than 20 mV. A failure indicates the Wideband Output (A5) assembly is probably at fault.

3914 A5: 0DB Output Attenuation Fault

The 6.5V reference (BRF6, BSRF6) is connected to the Unity Gain Amplifier circuit on the Wideband Output assembly which drives the output through the Attenuators. The Wideband Output assembly is set for 0 dB attenuation so the 6.5V input results in a 3.25V output into 50Ω. This 3.25V is connected to the RCL line which is routed to the +input of the adc circuit on the DAC assembly. The DAC assembly output is connected to the -input of the adc circuit and adjusted until a null is achieved. This determines the exact value of the Wideband output. This fault occurs if the determined Wideband output is over 6% ±1.0 mV. A failure indicates the Wideband Output (A5) assembly is probably at fault.

3915 A5: 10DB Output Attenuation Fault

The 6.5V reference (BRF6, BSRF6) is connected to the Unity Gain Amplifier circuit on the Wideband Output assembly which drives the output through the Attenuators. The Wideband Output assembly is set for 10 dB attenuation so the 6.5V input results in a 1.027V output into 50Ω. This 1.027V is connected to the RCL line which is routed to the +input of the adc circuit on the DAC assembly. The DAC assembly output is connected to the -input of the adc circuit and adjusted until a null is achieved. This determines the exact value of the Wideband output. This fault occurs if the determined Wideband output is over 6% ±1.0 mV. A failure indicates the Wideband Output (A5) assembly is probably at fault.

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