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TSP #226 - Saker 50kV Common-Mode Fiber Isolated Active Probe (XFVP) Review, Teardown & Experiments

9K views May 26, 2023 9:03 PM

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In this episode Shahriar reviews the Saker fiber-optically isolated active voltage probe XFVP. The fully galvanically isolated probe can reject common-mode signals in the tens of thousands of volts range. Signals with fast rising common-mode can also be rejected thanks to its high bandwidth of beyond 250MHz. Information about the Saker probe can be found here:

This review is organized as follows:

00:00 - Introduction & optical probe overview, principle of operation, dividers and accessories
05:07 - Full teardown of the probe head, probe body and 500x attenuator box
09:28 - Differential probe versus an optically isolated probe architecture
11:22 - Excess noise, SNR, dynamic range, THD and auto-calibration experiments
18:13 - Measured bandwidth of probe, S-parameters, gain ripple, phase response and group delay
19:47 - Measuring a GaN switching behavior with 400V of common-mode signal swing
27:03 - Concluding remarks​​​

TNP #36 - Teardown, & Failure Analysis of a Tektronix TCP0030 120MHz, 30A AC/DC Current Probe

13.5K views May 15, 2023 9:28 PM

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In this episode Shahriar takes a look at a pair of Tektronix TCP0030 current probes which fail the degauss function. The principle theory of the probe is discussed as well as the teardown of the probe head.
The failure is traced to a disconnected Hall effect sensor inside the transformer assembly. Unfortunately the assembly is fully potted and cannot be disassembled without destroying the part. A destructive disassembly shows the unique and intricate design of the transformer module and ultra thin embedded Hall effect sensor. Although neither of the probes could be repaired, the teardown and analysis provides insight in to the probe operation and typical failure point.​​​

TNP #35 - Teardown & Analysis of an InPhi 43Gb/s 8Vpp Differential Mach-Zehnder Driver ASIC & Module

12.5K views May 7, 2023 8:22 PM

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In this episode Shahriar takes a look at a high-speed driver module intended for coherent applications. The Mach-Zehnder driver circuit can reach speeds of 43Gb/s and provide up to 8Vpp into a differential modulator. The ASIC is realized in an InP HBT process and manufactured more than 21 years ago! The teardown shows the interface design as well as detailed circuit analysis & ASIC architecture.​​​

TNP #34 - Focus Stacking & Image Stitching Tutorial with Zeiss Microscope Motorized XYZ Axis Stage

13.9K views May 6, 2023 3:22 PM

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In this episode Shahriar continues his journey with upgrading the Zeiss microscope. The microscope is now entirely motorized including the XYZ axis. This, combined with a high-quality Nikon DLSR allows the creation of some extraordinary focus stacked imaged. The interface between the microscope & DSLR is handled through an LMScope adapter:

The microscope is controlled via a custom GUI which manages all of the microscope functions as well as a fully automated focus stacking routine.​​​

TNP #33 - Teardown, Theory & Experiments with an OmniChrome Helium-Cadmium (HeCd) 442nm Laser

18K views April 30, 2023 3:48 PM

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In this episode Shahriar dives into the detailed operation of a HeCd laser system. The laser head sub-components and principle operation is discussed as well as the teardown of the power supply and its primary sections. Various spectral measurements are performed on the laser output as well as the non-coherent emissions from the main laser cavity.​​​

TSP #225 - Teardown, Repair & Experiments with an Agilent E5052A 7GHz Signal Source Analyzer

14.7K views April 22, 2023 10:51 PM

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In this episode Shahriar takes a look at a faulty E5052A signal source analyzer. Despite their age, these signal-source analyzers are highly sought after and very valuable. Although the analyzer can measure phase noise, it reports the incorrect input signal power across frequency. Initial assessments shows that the reported measured power varies wildly across the band.
The system block diagram is shown and principle operation of the instrument is described. From there, a few measurements are devised to verify the operation of the detectors, power splitter, etc. The problem is traced down to a broken connector on a custom resistive power divider. After the repair, the instrument reports the correct power. The overall performance is verified by measuring the phase noise of a Signal House PNCS-1 using cross correlation techniques.​​​

TNP #32 - Quick Repair of a Fluke 732A DC (10V, 1.018V, 1V) Reference Standard

9.3K views April 22, 2023 5:15 PM

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In this episode Shahriar quickly repairs a faulty Fluke 732A DC Reference Standard. Although the unit does produce a good 10V and 1.018V output, the 1V output shows no voltage at all. A close examination of the schematic shows that the 1V output is derived through a resistor divider from the 10V source.
Since no resistance can be measured from the 1V to any of the other ports, it is suspected that the failure is caused by a broken connection behind the front panel. The connection is corrected and the unit produces all desired output signals.​​​

TNP #31 - Teardown, Repair & Experiments with HP 87421 & 83017A 26.5GHz Microwave System Amplifier

12.7K views April 9, 2023 10:58 PM

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In this episode Shahriar repairs an HP 87421 power supply in order to revive a HP 83017A 0.5-26.6GHz Microwave System Amplifier. The power supply has multiple bad capacitors which can be readily exchanged. An X-ray of a bad versus good capacitor is also shown. A custom cable must be made and the pinouts of each module should be revers engineered.
The amplifier successful powers on and various performance metrics are measured. S-parameters, noise figure, PSAT, OIP3 and detector are all measured and verified. The instrument used are the Keysight FieldFox, Junkosha RF cables, R&S NRP power sensor, R&S SMB RF Vector Generator and R&S ZNL20 real-time spectrum analyzer / network analyzer hybrid.​​​

TNP #30 - Teardown, Repair & Experiments with an Agilent 4349B 4-Channel High Resistance Meter

13.7K views April 2, 2023 10:28 AM

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In this episode Shahriar "repairs" an HP/Agilent 4349B 4-channel high-resistance meter capable of measuring up to 10^15 Ohms! The instrument has four independent channels and requires an external power supply for measurements.
The instrument does not boot, but unplugging and re-plugging the cables fixes this issue. After some analysis of the theory of operation, a 1G-Ohm resistor is used for performance verification. The resistor is also measured against the Keysight & Keithley 8.5-digit/7.5-digit multimeters as well as the Keithley 2470 1000V SMU.​​​

TNP #29 - How many LEDs can you light up with a hot dog?

14.4K views March 31, 2023 9:26 PM

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In this Episode Shahriar attempts to answer a fundamental scientific question, within the budget of The Signal Path. In this case, the question that has boggles scientists since the invention of LEDs: How many LEDs can you light up using a hot dog?!​​​

TSP #224 - Signal Hound SM435C 43.5GHz Real-Time Spectrum Analyzer Review, Teardown & Experiments

26.4K views March 26, 2023 12:08 AM

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In this episode Shahriar reviews the successor to the popular Signal-Hound SM200C, the SM435C Real-Time Spectrum Analyzer covering 100kHz – 43.5GHz with 160MHz of gapless I/Q steaming using a 10GbE optical interface. With its constantly improving Spike software and incredible 1THz/s sweep rate, the SM435C has the potential to be a dream software-defined radio as well as a powerful laboratory & field instrument. This detailed review is organized as follows:

00:00 – Introduction
01:47 – Instrument overview & design
03:49 – Teardown, detailed circuits & systems overview and analysis including X-Ray imaging
16:33 – Analysis of a 24GHz pulsed radar module, real-time capability, zero-span mode, fast sweeps
29:06 – Noise figure personality and noise-figure measurements features
33:40 – Phase noise personality and characterizing the internal instrument phase-noise
33:49 – mm-Wave transmit mixer characteristics, digital demodulation capabilities
39:05 – Wideband IF output for digital demodulation using a Keysight MXR & PathWave VSA
41:35 – Wideband IF output for rapid pulse hopping analysis using a Tektronix MSO-6B Series
45:06 – Additional Spike software features
46:11 – Concluding remarks​​​

TSP #223 - Teardown, Repair & Analysis of a Tektronix THDP0100 ±6kV High Voltage Differential Probe

14.8K views March 6, 2023 1:20 AM

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In this episode Shahriar repairs another high-voltage Tektronix probe, this time a THDP0100 which is capable of measuring 6kV signals up to 100MHz. The probe does not get detected by the scope. However, it soon becomes clear that the problem with this probe is much more involved than the previous repair.
The probe has a short-circuit inside the probe body as well as several damaged components. Each is replaced one step at a time until a final fault is also detected in the probe head. After the repair, the probe is zeroed, calibrated and used to measure a signal at 6kVpp using an Associated Research HYPOT tester.​​​