TNP #55 - Lab Upkeep Time! Agilent 3458A 8.5 Digit Multimeter & MSO9404A 4GHz, 20GS/s Scope Repairs
9.4K views
September 21, 2025 9:17 AM
In this quick episode Shahriar performs some regular lab maintenance. Two instrument need attention. The Agilent 3458A is reporting a Nonvolatile Memory Error & and the Agilent MSO9404A is reporting a dead CMOS battery.
Both problems are easily addressed by changing the battery backup. In the case of the 3458A, the calibration content has to be re-programed into the new NVRAM ICs.
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TSP #266 - Agilent 6GHz MXG Vector Signal Generator (N5182A) Teardown, Repair & Frac-N PLL Analysis
14.7K views
September 18, 2025 8:54 PM
In this episode Shahriar repairs an Agilent N5182A MXG Vector Signal Generator. The instrument produces the correct output signal for some set frequencies but reports a Fractional-N Unlock error for others while the output signal completely disappears. The instrument also fails many self-test checks.
The block diagram of the unit is described in details with a measurement strategy to analyze every element of the PLL loop. The band-pass filter banks are isolated and measured with a Siglent network analyzer and are shown to be fully functional. The VCO output amplifiers & doubler are also fully functional and tested using a Siglent spectrum analyzer. The PLL loop is then “overwritten” and manually adjusting the VCO control voltage demonstrates that the oscillator can cover its entire designed tuning range. The fractional-N divider also appears functional for the appropriate input frequency ranges. Finally, although the GaAs phase detector appear functional, it is possible for such a component to slowly degrade where the phase detection gain changes significantly. This custom Agilent part is sourced from a donor board and the instrument now functions across all frequency ranges and passes all self-tests.
The phase noise performance of the unit is verified against the datasheet using an Agilent E5052B signal analyzer with cross-correlation capability.
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TSP #256 - Thermal Camera Cooled to -196C! Cryogenic HgCdTe (MCT) Long-Wave Infrared Detector Magic
15.7K views
August 19, 2025 9:21 PM
In this video Shahriar dives into the amazing science & engineering of cryogenically cooled thermal cameras. This particular model, Inframetrics 760 Imaging Radiometer, was manufactured in the 1990’s and leverages a range of clever engineering techniques. It includes a miniaturized Stirling engine cryocooler, galvanometer based mirrors for 2D field scanning as well as a low-noise Mercury-Cadmium-Tellurite (HgCdTe) MCT detector sensitive in the 4-15um wavelength.
Teardown of the unit along with a detailed theory of operation is presented. The semiconductor profile and properties of MCT detectors are also discussed. Furthermore, a different thermal camera using a Joule-Thomson cryocooler and high-pressure (3000 PSI) Argon source is also shown.
After reverse engineering the critical detector interfaces, an experiment is devised to measure the thermal signature of a resistor. The setup includes a triangle wave driving a resistor to generate a time varying thermal source, Lakeshore M81 source-measure lock-in amplifier and chopper in front of the MCT detector and BLDC motor driver for running the cryocooler. The measurement demonstrates the functionality & sensitivity of the detector to capture black body radiation.
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TNP #54 - How Much Does YouTube Pay The Signal Path? Also Oscilloscope Giveaway Time!
15.3K views
August 2, 2025 10:10 PM
In this episode Shahriar shares the total ad revenue of The Signal Path since its inception in May 2011.
There is also another oscilloscope giveaway! This time it will be a Siglent SDS1000X HD, 4-Channel Oscilloscope. The winner will be randomly selected in one month.
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TSP #263 - Lakeshore M81 Synchronous Source Measure System (SSM) Review, Teardown & Experiments
15.5K views
July 31, 2025 2:11 PM
In this episode Shahriar reviews the newly released Lakeshore M81 Synchronous Source Measure System. This unique product combines three key metrology techniques into one: source/measure capability, high-dynamic range remote-heads and lock-in capability while maintaining both DC and AC modes. In my view, this is an entirely new instrumentation category:
https://www.lakeshore.com/products/product-detail/m81/the-m81-ssm-instrument
This review is organized as follows:
00:00:00 – Introductions
00:00:35 – Why is the M81 system a new type of instrumentation category?
00:04:51 – Instrument overview, font/back panels, module interfaces
00:07:42 – Complete teardown of all modules & mainframe
00:21:05 – AC & DC performance verifications, detailed GUI overview, mainframe usability
00:36:31 – Full BJT characterization, IV trace, thermal effects, MeasureLINK platform, sequencing measurements, scripting capabilities
00:46:28 – AC voltage & current linearity, THD & spurious performance verifications
00:51:48 – Lock-in capability, characterization of RC circuit phase response, harmonic measurement, DC + AC capabilities
00:59:37 – Ultrasonic liquid level measurement setup, lock-in phase tracking, MeasureLINK plotting over time
01:02:28 – Lock-in with externally modulate signals, photovoltaic effect of a glass-package diode, chopper signal synchronization
01:06:59 – Additional possible experiments, Lakeshore white papers
01:07:50 – Recommendations & concluding remarks
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