Fixing with the Flu – Keysight 53230A 15-Digit, 20ps Frequency Counter Repair, Teardown & Upgrade

March 1, 2026 No comments

In this episode Shahriar repairs a Keysight 53230A frequency counter with an unusual problem. The instrument reports OVERLOAD for both high & low thresholds on both Channel 1 & Channel 2 with or without an input signal. With this problem, the instrument also fails self-test.

There is no schematic or even a block diagram for this instrument. But since the unit is equipped with both the Microwave Pulse Measurement as well as the 15GHz Microwave input option (as Channel 3), it is certainly worth repairing. Channel 3 of the instrument is fully functional, which is a good sign for the health of the latter DSP portion of the unit.

Teardown reveals two parallel & identical Channel 1 & Channel 2. The circuits are examined in details and the primary comparators are identified. After some testing, it becomes clear that the comparator thresholds are controlled via some ADI DACs which are maxed out due to inactivity at the output of the comparators. Interestingly, the latch inputs ports of the comparator ICs are also controlled by a different DAC. This is the first part which is in common with both channels. After replacing this DAC, the instrument no longer reports the OVERLOAD error.

The instrument is also upgraded with an OCXO which should bring much better frequency stability. The unit is then calibrated against a Rubidium standard. The microwave pulse measurement is demonstrated first using a R&S SMBV100B Vector Signal Generator & Tektronix MSO-6B Mixed-Domain Oscilloscope. The Keysight 53230A is easily able to measure pulse duration, repetition as well as the carrier frequency. The frequency counter’s trend chart, histogram & other advanced DSP functions are also demonstrated.

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TSP #274 – How Heavy Is an Electron? The Experiment That Changed Physics – Scope Giveaway Results

February 8, 2026 No comments

In this episode Shahriar re-traces history and measures an important characteristics of a fundamental sub-atomic particle: the charge to mass ratio of an electron.

This experiment, first performed in 1897 by J.J. Thomson, changed physics by showing that atoms are indeed made of further sub-atomic particles through the discovery of electrons. We build a setup using a pair of Helmholtz coils, a cold-cathode vacuum tube driven by a multi-kV DC power supply & careful measurements of the beam deflection angle. The theoretical foundation of the experiment is described in details.

The measured e/m ratio is compared with the NIST established number with great agreement. The historical impact of the work of J.J Thomson & Robert Milikan (measuring the charge of an electron) are also presented.

The two winners of the giveaway are:

@nicolasblomstrand2912 (YouTube)
Robert S. (Patreon)

Each will receive a Siglent SDS1104X HD!
https://www.siglentna.com/product/sds1104x-hd/

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TSP #273 – I Bought a Bridge! World’s Most Accurate Capacitance Bridge Theory, Teardown & Experiment

January 16, 2026 No comments

In this episode Shahriar dives into the concept of a capacitance bridges. In particular, the Andeen-Hagerling AH2500A Ultra-Precision Capacitance Bridge:

https://www.andeen-hagerling.com/ah2500a.htm

The theory of operation is explained in details alongside a comparison with more traditional LCR meters. A simple replica transformer-based bridge circuit is also used to demonstrate the principle operation using a Zurich-Instruments MFIA lock-in amplifier. The teardown of the unit provides further insight into the engineering design of the instrument.

The capacitance bridge is also used to measure small shifts in a parallel plate capacitor. Furthermore, a complete set of air capacitor standard modules are calibrated & adjusted using the bridge as a standard.

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TSP #272 – I found a Chub! Fluke / Hart Scientific 1529 Chub Standards Thermometer Teardown & Repair

January 3, 2026 No comments

In this episode Shahriar take a look at a broken Chub. These instruments are able to measure PRTs, Thermistors as well as other resistive based thermometers. They can also be quipped with thermocouple reader modules.

This specific instrument has a blown fuse and draws an excessive amount of current. The first problem is a faulty 5V DC/DC converter. Although changing the IC does resolve the 5V power supply problem, it is likely that the failure has also caused excessive voltage to appear across the unit. There is no activity from the microprocessor. After replacing the processor and re-programming the EEPROM, the unit is up and running. A few experiments with various sensors and precision resistors verified the functionality of the instrument.

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TSP #271 – Rohde & Schwarz Compact 8-Channel MXO3 12-Bit Oscilloscope Review, Teardown & Experiments

December 20, 2025 No comments

In this episode Shahriar takes a close look at the all new R&S 8-Channel MXO3 series oscilloscope. Despite its size, the scope retains many of its hardware accelerated functions, such zone & frequency domain triggering as well as fast spectrum modes. You can find the scope here:

https://www.rohde-schwarz.com/products/test-and-measurement/oscilloscopes/rs-mxo-3-oscilloscope_334309.html

The review is organized as follows:

00:00 – Introductions, instrument overview, overall design, interfaces
04:39 – Detailed teardown, architecture, ADCs & chipsets
11:24 – Scope class compromise philosophy
12:16 – GUI overview, sampling rates, ease of use, menu organization
15:40 – Arbitrary waveform use, waveform capture rate caveats, histograms
18:06 – SFDR, THD, noise, dynamic range, spectrum view, isolation
24:16 – DVM application, application modes, HD mode
25:38 – Connecting several signal types for analysis
25:51 – Time domain zone triggering function, rare event capture
28:11 – Frequency domain zone triggering, event rate comparison
31:58 – Power analysis application capabilities
35:00 – Hardware accelerated math function, differential signal, mask mode
36:42 – Enabling all waveforms at once, instrument speed & responsivity
37:45 – Front panel thermal considerations
37:57 – Which scope should you buy? Concluding remarks

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