Archive for October 16, 2014

Keithley 2450 Source Measure Unit (SMU) Review and Experiments

In this episode Shahriar reviews the new Keithley 2450 Source Measure Unit (SMU). This model, which is the successor to the widely adopted Keithley 2400, offers performance improvements as well as a brand new interface platform with multi-point touch screen.

The review demonstrated the instruments GUI, scripting capabilities through the TSP interface and various performance parameters. Furthermore the scripting features are used to measure super capacitor capacity, the performance of a wireless charging system, characterization of optoelectronic components and semiconductor elements.

Teardown, Analysis and Repair of an HP/Agilent 5347A 20GHz Frequency Counter and Power Meter

In this episode Shahriar takes a close look at an HP/Agilent 5347A 20GHz Frequency Counter and Power Meter. This defective unit does not provide any frequency information from Input 2 which is rated to operate up to 20GHz. Before the teardown and repair attempts, the principle operation of the instrument is reviewed.

The properties of a Step Recovery Diode (SRD) is presented along with the theory and practical aspects of generating a frequency comb. The heterodyne architecture of the frequency counter is explained in detail with the mechanism of detection and calculation of the input frequency.

During the teardown of the unit the synthesizer board, motherboard, power meter reference board and the main RF assembly are shown. The schematic of the synthesizer board and the RF board are also described. The defective component is identified and examined under the microscope. The slides for this episode can be found here.

Teardown, Analysis and Repair of an Agilent E4407B 26.5GHz ESA-E Spectrum Analyzer

In this episode Shahriar takes a detailed look at an Agilent (Keysight) E4407B ESA-E Spectrum Analyzer. The instruments reports an “Unlock LO” error message which prevents internal alignments from being performed. Before the repair process can begin, the firmware of the instrument must be updated. The firmware upgrade requires the installation of additional flash memory ICs which is presented in the video. The main processor board with its various components are also described in the video.

The complete block diagram of the spectrum analyzer is presented with a detailed look at the principle of operation of the instrument. All the main functional blocks such as the YIG Oscillator, Phase Detector, LO Path, LO Amplifier, Charge Pump, Pre-tune segments, digital circuits, IF and LO paths are analyzed both in schematic and on the PCB. Several potential faults are investigated and measured.

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