TSP #204 – Teardown, Tutorial & Experiments with Active/Passive Microwave Band-Pass Filters (APS104)

In this episode Shahriar repairs an OPTOELECTRONICS APS-104 tunable band-pass filter. The instrument provides continuous tuning from 20MHz to 1GHz with a constant 4-MHz band pass response. Since the repair proves to be fairly easy, the video focuses on comparison between various band-pass filter architectures. This includes microwave cavity filters, PCB-based filters with varactor tuning, YIG filters and frequency-translation filters. A range of measurements highlight the differences and pros/cons of the aforementioned filters. The APS-104 unit is fully reverse engineered and characterized as well.

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TNP #13 – Teardown & Repair of a Keithley 2001 7.5 Digit Multimeter

In this episode Shahriar repairs a Keithley 2001 7.5 Digit multimeter. This is a very high performance unit and worth repairing. However, the early 90’s revision of these units were subject to electrolytic capacitor failure all overt the analog and digital boards. The failed capacitors destroy the nearby traces including the inner layer connections. The teardown of the unit reveals this problem. By using x-ray imaging the missing and damaged traces are identified and meticulously repaired. Several of the power supply diodes were also destroyed. The repaired unit passes all self-tests as well as measured V/I/R in both DC and AC correctly. The unit is compared with measurements reported by a Keithley DMM7510.

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TNP #12 – Teardown, Repair & Experiments with the Fluke 345 Digital Power Quality Clamp Meter

In this episode Shahriar repairs a Fluke 345 Digital Power Quality Clamp Meter. The Fluke 345 is more than an electric power meter. Combining the functions of a clamp meter, oscilloscope, data logger and digital power meter into one handy device, the Fluke 345 is ideal for working with variable frequency motor drives, high efficiency lighting and other loads using switching electronics.

Although the repair ends up being fairly simple, we get some insight into some of the user interface circuitry as well as some experiments showing the capabilities of the unit.

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TSP #203 – Teardown, Upgrade & Experiments with an Agilent 3400B High-Dynamic Range True RMS Meter

In this video Shahriar upgrades an Agilent 3400B RMS meter to add an LCD-based GUI interface and USB digitization capabilities. This excellent instruments offers high RMS frequency range of 10Hz – 20MHz and can reliably measure 100uV RMS – 300V RMS! The instrument uses purely analog techniques to accomplish this.
The theory of operation of the instrument is presented in details along with the challenges of adding digital circuits among such a sensitive analog domain. The upgrades use two modules which communicate through a serial interface and use an ADC to digitize the measured analog RMS value. A new GUI interface is developed to display a wide range of useful information simultaneously as well as historical data trend line. The instrument is used to perform several measurements including measuring the output noise of a DC/DC converter module.

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TSP #202 – A Uniquely Complicated Nixie Tube Clock: HP 5245L Electronic Counter & ERA EasySynth++

In this episode Shahriar repairs and analyzes two instruments. An HP 5245L Electronic Counter which uses 1960’s technology to achieve some incredible performance. The HP unit uses eight beautiful nixie tubes as its main numeric display. The instrument requires repair, calibration and some upgrades to prepare it for use as a nixie tube clock! The source of the clock is an ERA Instruments EasySynth++ which is a high performance, open-source synthesizer up to 20GHz:

https://erainstruments.com/

The architecture and teardown of the EasySynth++ is also presented. The two instruments are combined with some custom scripts to create the world’s (?) most complicated nixie tube clock.