Archive for General

Teardown, Analysis & Part-Salvage from an HP 70001A Series Optical Microwave Analyzer


In this episode Shahriar performs a teardown and analysis of several HP 70000A modules. The modules include a 20GHz optoelectronic converter, 2.9GHz tracking generator, 10MHz/100MHz precision reference and a 22GHz spectrum analyzer.

Along with the teardown of these modules several microwave components are recovered for future use including amplifiers, VGAs, mixers, photo detector and OCXOs. The 22GHz spectrum analyzer module is preserved since it is simply too beautiful to destroy.

My Interview at The Amp Hour!

The Amp Hour

I had a great time as a guest of The Amp Hour. We talked about everything from device physics to circuit design into the mm-wave frequencies and beyond. Although this interview took place a short while ago, I thought it would be beneficial to also have a link here at The Signal Path. Also, don’t forget to listen to the many great episodes of The Amp Hour. The link to my interview can be found here.

Teardown and Repair of an Agilent E4433B ESG-D Synthesized Signal Generator


In this episode Shahriar repairs an Agilent E4433B ESG-D Synthesized Signal Generator. This 4GHz unit shows the “UNLEVEL” error for all frequencies and at all output power levels. After a close look at the system block diagram the fault is traced to the main Output RF board.

The Output RF board is equipped with various amplifiers, electronic attenuators, I/Q mixers, heterodyne paths and final PA. By using soldered SMA cables to various points in the signal path, the fault is traced to an internal amplifier chain which is likely made of a MESFET or JFET transistor. Since this part is obsolete, an RFMD GaAs hybrid amplifier is used in its place. The biasing network and matching networks need to be modified to accommodate this change. The repaired unit is then verified for functionality and performance by measuring a QAM constellation output signal.

Agilent 53131A Universal Counter Upgrade OPT-030 Analysis and Experiments


In this episode, Shahriar upgrades an Agilent 53131A Universal Counter with the OPT-030 which extends its frequency range from 225MHz to 3GHz. The upgrade kit is a replica PCB intended to emulate the behavior of the original Agilent branded option.

The PCB is examined carefully with attention to microwave layout techniques along the signal path. The datasheet of all the parts are reviewed and the reverse-engineered block diagram of the PCB is presented. The expected behavior of the PCB is then measured in both small-signal and large-signal operation using an active 3GHz probe. The PCB is then installed inside the unit and the functionality of the instrument is verified within its specifications. All the documents presented in the video can be found here.

Tutorial on Microwave and mm-Wave Components and Modules


In this episode Shahriar demos various microwave and mm-wave connectors, components and modules. The purpose of this video is to help new engineers become familiarized with microwave components and help reduce the chance of component damage and failure.

This video demonstrates microwave connectors (BNC, SMA, 3.5mm, 2.92mm (K), 2.4mm, 1.85mm (V), 1.0mm), interfacing instructions, attenuators, power splitters (both resistive and reactive), phase shifters, mm-wave cables, AC coupling caps, Bias-Ts and their principle of operation, mixers, tuning stubs, couplers, switched attenuators, microwave filters, multipliers, amplifiers, coaxial to waveguide converters, waveguide components including horn antennas, and directional couplers. The video also demonstrates Cascade GSG probes and GGB custom composite RF probes. The documents for this video can be downloaded from here.