Archive for August 12, 2018

Tutorial, Experiment & Teardown of a 24GHz Doppler Radar Module

In this episode Shahriar demonstrates a full analysis of a CDM324 24GHz Doppler radar module from IC Station. Opening the module reveals a series of microwave PCB components and several active devices. A complete analysis of the module is presented. The unit is then measured and the impact of antenna impedance and power supply voltage on the output frequency is measured. The phase noise of the output signal is also measured. Using a series of servo motors, the radiation pattern of the antenna array in both azimuth and elevation is also presented.

Using the radar module the speed of a computer fan is remotely measure using an oscilloscope and FFT function.

All proceedings from Patreon for this video will be donated.

Teardown, Repair and Analysis of an Agilent 4338B (10uΩ – 100kΩ) Milliohmmeter

In this episode Shahriar repairs an Agilent 4338B milliohmmeter. This instrument is capable of measuring extremely small resistances down to 10uΩ while maintaining a DUT voltage of less than 20mV. The instrument powers on with the message ADC Failure. Investigation reveals that the instrument uses an obsolete ADC which must be removed from the board in order to reverse engineer its operation. While the ADC turns out to be functional, a PAL device which controls the ADC timing is faulty. A new device is salvaged from a donor board to complete the repair. The instrument is then used to measure several small known resistances.

Signal Hound PNCS-1 1GHz Phase Noise Clock Standard Review, Teardown & Experiments

In this episode Shahriar takes a close look at the new Signal Hound PNCS-1 clock standard module. The purpose of this instrument is to provide an exceptionally clean phase noise reference at 1GHz in order to characterize other instruments such as spectrum analyzers and oscilloscopes.

The unit uses an OCXO at its heart running at 100MHz. The signal is them multiplied by a factor two and then a factor of five while being filtered and amplified in order to generate 1GHz. The complete signal path of the instrument is analyzed. The unit is then used on an Agilent MXA generator to characterize its phase noise. A frequency divider is also used in conjunction with the PNCS-1 in order to create lower frequency signals.

Teardown, Repair and Experiments with an Agilent E4981A High-Speed Capacitance Meter

In this episode Shahriar investigates an Agilent E4981A high-speed capacitance meter which fails self-test during startup. The instrument reports a series of errors associated with the CPU board. The teardown reveals a multi-board construction where the main analog assembly employs an FPGA for control and interface to the main CPU board. The unit has a disconnected ribbon cable between the analog board and the main CPU assembly. After correcting the problem the instrument completes self-test without errors.

After the repair the unit is used to measure several known capacitors for functionality verification. Finally the instrument is used to measure a hand-made parallel plate capacitor. The capacitor can accept various types of dielectric material whose impact is studied.

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