Tag Archive for Parts

Teardown & Analysis of an Agilent 86109B Optical/Electrical DCA-X Oscilloscope Module

86109B

In this episode Shahriar presents the inner workings of an Agilent 86109B optical/electrical DCA-X oscilloscope module. This particular model offers up to 50GHz of electrical bandwidth and an optical input capable of receiving up to 40Gb/s data rates. The differences between a real-time and sub-sampling oscilloscopes are presented with focus on ADC resolution, signal periodicity requirements and input bandwidth. The block diagram of the module as well as a sub-sampling oscilloscope is also presented.

The teardown of the module shows various components such as samplers, O/E conversion block, impulse generator as well as a step-recovery diode driver. I/O interfaces as well as various analog blocks are also shown. Several modules are further disassembled to observe the inner semiconductor designs under the microscope.

Tutorial on High-Power Balanced & Doherty Microwave Amplifiers

Balanced Amplifier

In this episode Shahriar demonstrates the architecture and design considerations for high-power microwave amplifiers. Two architectures are presented, the balanced and Doherty microwave amplifiers. The block diagram, circuit properties and the pros/cons of each architecture are presented. Two available high-power amplifiers modules for cellular applications are also examined. The PCBs show an implementation instance of each amplifier type capable of delivering 100W of RF power. The datasheet of various components as well as an overall system structure are also presented.

Teardown & Repair of an Agilent 54845A 1.5GHz 8GS/s Infinium Oscilloscope

54845A

In this episode Shahriar repairs an Agilent 54845A oscilloscope with an intermittent failure. The instrument occasionally fails self-calibration and the displayed waveform shows undesired spurious activities. The teardown of the instrument reveals customized front-end section coupled into a ceramic-substrate ADC ASIC designed by Agilent. The packaged ADCs are placed in sockets. The ICs are removed and the ceramic carrier is cleaned; this resolves the intermittent problem with the channels. The architecture of the scope is also presented. The functionality of the scope is verified through self-calibration, self-test and measurement of various waveform.

Fluke PM6680B Frequency Counter 10MHz OCXO Reference Upgrade Module

OCXO Module

In this short episode Shahriar upgrades the recently repaired Fluke PM6680B with a new OCXO design by Dan Watson. The design of the module is examined as well various considerations for providing ultra clean 10MHz reference for instrumentation.  After module installation the unit functionality is verified. More information about the module is available here and here.

Teardown and Repair of a Fluke PM6303A Automatic RCL Meter

PM6303A

In this episode Shahriar examines a faulty Fluke PM6303A Automatic RCL Meter. This unit power on however reports the incorrect measured value for all components. The instrument also does not provide the built-in 2V bias. After a quick teardown of the unit, physical damage to several input resistors can be observed. It becomes clear that a high-voltage discharge has caused a cascade failure of several components on the input signal path. These faults are traced to a chain of protection Zener diodes, resistors and general purpose diodes. After all the components have been replaced, the unit’s functionality is restored.

The schematic and block diagram of the unit is also presented and the principle of operation is explained. The repaired instrument is then used to measure several components to verify is functionality.

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