TNP #21 – Stanford Research SR630 16-Channel Thermocouple Monitor Teardown, Repair & Experiment

October 6, 2022 No comments

In this episode Shahriar takes a look at a Stanford Research SR630 16-Channel Thermocouple Monitor. This instrument provides accurate temperature readings multiplexed from 16 unique inputs. It also supports a wide range of thermocouple types. The instrument is purposely not powered on initially as it is prone to capacitor leakage on the main board. The capacitors have destroyed many of the crucial traces all of which have to be individually replaced with wires.
Repair is successful and the instrument is back to life! To test the unit, the temperature on both surfaces a Peltier cooler is measured. The thermoelectric pump is able to cool one side to below -5C while consuming 3.5W.

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TSP #214 – What is a good RF cable? Junkosha Phase/Amplitude Stable Cable Theory & Experiments

September 18, 2022 No comments

In this episode Shahriar discusses the engineering challenges associated with making good RF & mm-Wave cables. The significance of the connector, cable frequency range, loss, phase/amplitude stability & temperate are all examined from a theoretical & practical aspects.

The stability of Junkosha cables are demonstrated up to 50GHz through S11 & phase measurements. The Junkosha MWX7 series cables offer optimized PTFE dielectrics as well as some of the best phase/amplitude/temperature stable operation:

https://www.junkosha.com/en/products/EMF-07

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TSP #213 – Keysight 20GHz MXG Analog RF Signal Generator Teardown, Repair & Analysis (Part 2)

September 4, 2022 No comments

In this episode (Part 2) Shahriar returns to the MXG repair! The awesome engineers at Keysight have provided a replacement for the suspect part! The exchange is not easy due to the component’s strict thermal requirements. A method to provide a good thermal & electrical contact is presented. The repaired instrument is verified for functionality.
A close look at the complex micro-module is also presented under the microscope with analysis of each sub-component ceramic part & III/V MMIC.

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TSP #212 – Siglent SNA5000A 8.5GHz 4-Port Vector Network Analyzer Review, Teardown & Experiments (I)

August 28, 2022 No comments

In this episode (Part 1) Shahriar presents a detailed review of the Siglent SNA5000A series vector network analyzer. The Siglent SNA VNA has a frequency range of 9 kHz to 8.5 GHz, with 2- and 4-port models available. Designed to give you instant insight into scattering, differential, and time-domain measurements. Siglent VNAs enables measurements of the Q-factor, bandwidth, and insertion loss filters and feature impedance conversion, movement of measurement plane, limit testing, ripple test, fixture simulation, and adapter removal/insertion adjustments. There are five sweep types: Linear-Frequency, Log-Frequency, Power-Sweep, CW-Time, and Segment-Sweep mode. SNA5000A VNAs also support scattering-parameter correction of SOLT, SOLR, TRL, Response, and Enhanced Response for increased flexibility in R&D and manufacturing applications:

https://siglentna.com/vector-network-analyzer/sna5000a/

This (Part 1) of the review is organized as follows:

00:00 – Introductions.
01:02 – Instrument overview, design, user & RF interfaces.
04:27 – Detailed teardown, architecture, RF design & VNA board reverse engineering.
18-21 – Calibration, E-Cal compatibility, built-in procedures, initial GUI overview.
22:12 – High rejection filter characterization, pushing the dynamic range limit, port-to-port isolation, IF BW, filtering & averaging.
28:28 – Characterizing active devices, measurement topology, differential & common-mode responses, power control, waveform comparison, phase & magnitude response.
39:07 – Sweep types, power sweep, compression measurements, non-linear DUT characteristics, impedance & Smith charts.
44:12 – VNA as RF synthesizer, CW generation, tone purity & power accuracy.
45:26 – Concluding remarks.

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TSP #211 – Keysight 20GHz MXG Analog RF Signal Generator Teardown, Repair & Analysis (Part 1)

August 20, 2022 No comments

In this episode Shahriar investigates a failed Keysight MXG RF generator. The instrument shows UNLEVEL for frequencies above 10GHz. The measurements confirm that the instrument fails to achieve the desired output power. The block diagram of the synthesizer is examined in details and potential failure points are identified.
The teardown of the instrument and various components are also presented. A detailed description of the multiplier unit is shown along with the PCB X-Ray. Measurements confirm the failure of an Agilent-branded component (doubler + amplifier module). The repair has to be paused for now until a replacement component is sourced.

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