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TNP #39 - Faxitron MX-20 Digital Micro-Focus X-Ray Machine Teardown, Repair & Experiments

The Signal Path views September 17, 2023 4:16 PM

In this episode Shahriar repairs his Faxitron MX-20 digital x-ray system. Although the machine has been producing beautiful images for years, recently it has been outputting out-of-focus images intermittently.
The principle of x-ray focusing and beam-spot generation is presented along with potential electronic methods of achieving focus. The teardown of the unit reveals the main x-ray tube controller PCB which houses the focus control high-voltage modules. Since the problem is intermittent, a reed switch is also suspected. The high-voltage module is measured and appears fully functional. Replacing the reed switch corrects the out-of-focus images. Several x-ray images showcases the sharpness of the unit after the repair.

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TSP #232 - Near-THz Sub-Harmonic Mixers (Tektronix 75 - 140GHz) Tutorial, Teardown & Experiments

The Signal Path views August 12, 2023 8:05 PM

In this episode Shahriar takes a deep dive into near-THz sub-harmonic mixers. To demonstrate the concepts, measurements and teardowns a set of Tektronix Sub-Harmonic mixers have been acquired (WM 490-F & WM 490-W) which operate from 90-140GHz & 75-110GHz respectively. This video is organized as follows:

00:00 - Introductions
00:50 - Acquired near-THz sub-harmonic mixers & diplexers
01:26 - Theoretical background, non-linear devices, harmonic generation
06:05 - Spectrum analyzers utilizing sub-harmonic mixers, signal ID
08:27 - Tektronix sub-harmonic mixer design, schematic & principle of operation
15:11 - Mixer diode characterization using Keithley SMUs & I/V tracer application
19:59 - Mixer teardown, analysis and microscope view of THz diode
28:07 - Diplexer architecture & characterization using a 4-port Siglent network analyzer
33:24 - Complete near-THz down-conversion setup using a x6 mm-wave multiplier source and Tektronix MSO68-B oscilloscope, conversion loss, harmonic number verification, signal ID process
45:35 - Using a ~100GHz carrier to determine the RPM of an optical chopper
48:15 - Concluding remarks

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TSP #231 - Sanko BN100+ 300kHz - 6.5GHz USB Vector Network Analyzer Review, Teardown & Experiments

The Signal Path views August 7, 2023 7:28 PM

In this episode Shahriar reviews the Sanko BN100+ USB vector network analyzer which has been designed in partnership with Bird RF:

The review is organized as follows:

00:00 - Introductions
00:27 - Instrument front & back panels
02:15 - Teardown, internal architecture, front-end coupler design
06:03 - Firmware distribution
06:36 - VNA output signal performance, sweep types, sweep speed, harmonics (THD), power sweep
14:00 - Calibration, built-in models, calibration procedure & standards
15:35 - Port to port isolation, noise floor, minimum detectable response
16:18 - Extreme filter dynamic range measurements
18:07 - VGA measurements, dynamic s-parameters, trigger in/out
24:11 - Time domain analysis, impulse response measurements
26:27 - Frequency accuracy measurements
27:01 - Concluding remarks​​​

TSP #230 - A Real-Life Tricorder! Agilent Raman Resolve Through-Barrier Chemical Analyzer

The Signal Path views July 20, 2023 7:49 PM

In this episode Shahriar takes a close look at the Resolve Handheld Raman Analyzer for Chemical Identification from Agilent. This instrument resembles a real-life Tricorder with its ability to identify chemicals through various opaque containers.

This video explores every aspect of this instrument's design from principle of operation to the modern electronics required to realize its function. The video is organized as follows:

00:00 - Introductions & first through-barrier scan example
02:46 - Raman history, invention & Nobel prize
04:41 - Infrared absorption, Raman spectroscopy theory, challenges and importance of fluoresce
10:49 - Fluorescence example & measurement using Uranium glass & HeCd laser
15:21 - Other applications of fluorescence such as microscopy
16:48 - Nonlinear optical effect and frequency doubling crystals, measurement of green laser
20:13 - Other applications of nonlinear optics, autocorrelation instrument to measure femtosecond pulses
23:18 - Electron excitation of atoms to produce photon emissions using Helium & Neon gasses
24:23 - Components required to build a Raman spectrometer
25:15 - Monochromator & spectrometer architectures, limitations & design
29:07 - Agilent Raman Spectrometer overall architecture, Raman chemical fingerprints
31:10 - Spatially Offset Raman Spectroscopy (SORS) theory & application
32:43 - Agilent Raman Resolve use-cases, accessories and application scenarios
36:03 - Measurements & identification of spilled unknown powders & liquids
40:53 - Through-barrier plastics & glass measurement of mixed liquids & acids
42:52 - Agilent Resolve extensive library & material categories, Reach-back support
44:03 - Chemical identification examples using the Vial accessory
47:26 - Trace chemical concentration & sensitivity measurement
48:34 - Concluding remarks

Data TNG image credit:​​​

TNP #38 - SourceTronic ST2516 Micro-Ohm DC Resistance Meter Teardown, Modifications & Experiments

The Signal Path views July 6, 2023 9:31 PM

In this experiment Shahriar modifies a SourceTronic DC resistance meter due to its incredibly loud built-in buzzer. The instrument can sink up to 1A through a DUT and therefore measure down to micro-ohm resolution. The instrument also has offset voltage compensation capability to eliminate thermoelectric effects from bimetal contacts to the DUT. A direct measurement of the DUT current shows how the instrument is able to do this task in the background while measuring low resistances.​​​

TSP #229 - Stanford Research DS360 Ultra-Low Distortion Function Gen. Repair, Teardown & Experiments

The Signal Path views July 4, 2023 10:27 PM

In this episode Shahriar takes a look at a faulty SRS DS360 ultra-low distortion function generator. This instrument is capable of producing pure sinusoids with better than -110dB of THD!
Although the unit powers on, changing the frequency or output signal does not result in any internal relay switching and the instrument does not produce any output signal.
The block diagram of the instrument as well as the theory of operation is described before the teardown. The teardown also shows the two board design and the interface between the digital/analog boards. The fault is finally traced to a broken optoisolator IC between the two boards. Without this interface IC none of the configuration parameters from the digital board arrive to the analog subsection. The faulty part is replaced and the unit is restored. The difficult measurement of the THD is also presented using an SRS SR830 DSP lock-in amplifier.​​​

TNP #37 - Fluke 789 ProcessMeter Teardown, Repair & Performance Verification

The Signal Path views July 2, 2023 4:04 PM

In this episode Shahriar investigates the problem preventing a Fluke 789 PrceossMeter from powering on. The issue is fairly simple and is quickly identified.
The basic functionality of the instrument (DC/AC voltage, current, resistance measurements) are verified as well as the current delivery of the unit.​​​

TSP #228 - Biggest Microwave Components & Instrumentation Exhibition - IEEE Microwave Symposium 2023

The Signal Path views June 25, 2023 5:11 PM

We are back at the International Microwave Symposium 2023, this year held in San Diego, California!

The industry exhibition event was absolutely huge this year, with the latest showing in microwave, mm-wave & THz components, instrumentations & test solutions. This video covers a tiny fraction of the latest gear on display. The video is organized by vendor:

00:00 - Introductions
00:53 - Rohde & Schwarz:
07:36 - Keysight Technologies:
14:21 - Anritsu:
18:07 - Tabor Electronics:
19:33 - LPKF:
21:12 - Siglent:
23:40 - Eravant:
27:26 - Junkosha:
30:27 - VDI:
31:35 - FormFactor:
33:49 - HyperLabs:
35:01 - Samtec:
36:36 - QuinStar:
37:43 - MPI Corporation:
40:33 - Tektronix:
41:53 - Pickering:
45:20 - Boonton Instruments:
48:52 - Holzworth Instrumentation:​​​

TSP #227 - A 30GHz Static Frequency Divider from Fraunhofer Tutorial, Teardown & Characterization

The Signal Path views June 24, 2023 12:20 AM

In this episode Shahriar presents a deep dive into mm-Wave frequency divider; in particular static frequency dividers. These blocks are ubiquities in nearly every modern integrated circuits. The principle operation, circuit topologies and limitations are presented with several publications as examples.
The 30GHz static divider is then characterized extensively in both time domain and frequency domain. The measurements includes self-oscillation frequency, output waveform shape, input/output phase-noise relationship and the impact of temperature on self-oscillation frequency.
A detailed module teardown is also presented with focus on packaging techniques as well as closeup of the die. The integrated circuit is analyzed and the relationship between the schematic and layout is established.​​​

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

The Signal Path views May 26, 2023 9:03 PM

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 - Tektronix TCP0030 120MHz, 30A AC/DC Current Probe Teardown, & Failure Analysis

The Signal Path views May 15, 2023 9:28 PM

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 - InPhi 43Gb/s 8Vpp Differential Mach-Zehnder Driver ASIC & Module Teardown & Analysis

The Signal Path views May 7, 2023 8:22 PM

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.​​​