• Introduction and motivation
• Disclaimer
• Restoration, adjustment and calibration of old HP 3458A for SG Lab
  • Teardown and conditions investigation
• Refurbishment, adjustment and calibration of Keithley 2002 for SG Lab
• Recalibration for Keithley 2002 from LC Lab
• Conclusion and future plans

Introduction and motivation

Calibration festival is small unofficial offline event dedicated to meet with passionate people related to science of measurements – metrology. CF’s main purpose is to share the costs of high level calibrations for electrical units such as SI Volt and Ohm into our hobby labs and personal equipment, as well as showcase what is possible to achieve for metrology applications with limited budgets.

One of the main inspiration sources – inter-lab comparisons performed on the level of NMI and reports published on BIPM KCDB. Idea is to replicate similar project but at much lower hobby-level personal budget and scale. None of us is able to cover full-featured measurement laboratory or establish direct realization of SI unit at quantum level, but teamed up together we can hopefully get pretty close to the top of the uncertainty pyramid in specific measurements.

CF2024 main meeting event was held offline in NJ, USA location during 26 August 2024 – 31 September, 2024. However, preparation for experiments and measurements with equipment dedicated for event began as early as March 2024 and completed only after in September 2024. Most of the experiments were automated with Python to allow execution in parallel and reduce risk of human-induced errors in data.

Automation was handled by compact single-board computer Raspberry Pi with communications over GPIB and Ethernet interfaces. Software used for most of experiments is written in Python language. Key tools are internal use xDevs CalKit packages, as well as publicly available xDevs TECkit package. All experiments results were recorded in CSV-type RAW data files and further processed by various analysis packages. In-house analysis Python apps and licensed commercial MIL 6000B software was used for high resistance measurements with MIL 6000A bridge system.

Disclaimer

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Performance of each particular instrument may be worse or better than shown in this article. For details consult with manufacturer specifications and perform your own testing. Don’t take data presented here as typical results from other instruments, even of the same model/year. All data presented here is NOT accredited and NOT certified to be free of errors. Proceed with this warning in mind.

CalFest 2024 xDevs key members

• TiN (pilot xDevs lab)
• IO (NJ Lab)
• TM (FL Lab)

Special guests and visiting members

• LC (LC Lab, Canada) – visiting August 27 – August 30, 2024, car road-trip
• SG (SG Lab, Canada) – visiting August 31 – September 1, 2024, air-plane trip
• VC (VC Lab, Ukraine) – remote participation with K2010 project
• TheSignalPath (USA), car road-trip
• TML (New York, USA) – visit to discuss metrology and calibration industry, August 28, 2024, car road-trip

Experiments during this CalFest meetup

• DC Voltage standards comparison at 10 V
• Inter-comparison with resistance standards at 10 kΩ and 1 Ω
• Calibration for xDevs members Fluke 5450A’s with resistance bridges
• Restoration of Keysight 3458A 8½-digit DMM for SG Lab
• Adjustment and calibration of Keithley 2002 8½-digit DMM for SG Lab
• Imaging of RoHS Keysight 03458-66533 A3 PCBA
• Linearity verification of the various 8½-digit DMMs
• Adjustments and calibration of Keithley 2010 7½-digit DMM.

Restoration, adjustment and calibration of old HP 3458A for SG Lab

Due to time and scheduling constrains SG Lab shipped two of their DMMs via the regular postal service. Instrument was received on August 12, 2024. HP3458A packaging was pretty decent with foamed pads and styrofoam sheets. No exterior box damage was observed. But opening the bag and getting instrument out revealed a different story.

SG Lab repaired this instrument and brought it to “SELFTEST PASSED” condition, and now the idea of bringing it to xDevs is to do touchup fixes for cosmetics, verify electrical performance and perform full adjustment and calibration afterwards. This activities will take place from August 15 until August 31.

Front plastic bezel was smashed by Hulks and top section above the display is completely cracked off. Left side corner is completely broken off, barely hanging on the instrument frame.

Crack on the top goes all the way and plastic parts are loose and all around.

Right side near the binding posts is in a better shape but have all the lips smashed.

Binding posts are loose inside, hinting on the mounting ear damage at the front panel plastic. 3458A’s design has a weak point, especially if the posts are not protected by the rackmount handles.

This HP3458A has serial number 2823A18613 and does not have options 001 or 002. Non-original mount of the IEC C14 power receptacle hints us on replaced paffner :)

Left side:

Welcome another look on “Hot-Rod 3458A Open Top Edition”. I’m impressed that fragile glass display is actually intact and still bright.

Rear bezel cracked in half on the right short side with whole mount point shattered off. So it wouldn’t be securing covers much anymore.

There are also alien non-factory modifications detected, tapped holes drilled into the chassis frame on the right side.

Left side have alien bolts holding the covers as well. :)

Teardown and conditions investigation

This is the first 3458A I’ve received that had improved temperature oven setpoint modification on A9 LTZ1000A-based reference module :)

This 3458A is already sporting brand-new RoHS Keysight-built A3 PCBA, since original old HP board was sick with bad U180.

Refurbishment, adjustment and calibration of Keithley 2002 for SG Lab

SG Lab acquired Keithley 2002 from fellow Ken to improve SG Lab measurements capabilities. Instrument was shipped two weeks prior the Calfest visit, cleaned and serviced by xDevs. Freshly adjusted Fluke 5720A calibrator was utilized to perform the two calibrations of all key points and functions, as well as adjustment.

Calibration report for Keithley 2002, as received, 24 hr spec, August 28 2024

This DMM had large offset about 22ppm on DC voltage ranges and large errors on resistance function. Self-test or extended diagnostics did not reveal any major issues, so we proceeded with adjustment. Report after adjustment is available below.

Calibration report for Keithley 2002, as adjusted and returned, 24 hr spec, August 29 2024

This DMM is all happy and reporting “all green” for meeting 24-hour specifications after adjustments, as expected from fresh calibration.

Calibration for HP 3458A for LC Lab

LC Lab acquired old HP 3458A to improve the measurements capability. Owner cleaned up and recapped the instrument, repaired the front panel mechanical damages and started a stability testing for first few months of runtime. Now that unit is hand-carried to/from xDevs we performed adjustment using the transfer Fluke 732B and Fluke SL935 standards to provide accurate reference point for this HP 3458A. Freshly adjusted Fluke 5720A calibrator was utilized to perform the calibration of all key points and functions that 3458A offers.

Calibration report for HP 3458A, as adjusted and returned, 24 hr spec, August 29 2024

Recalibration for Keithley 2002 from LC Lab

This 8½-digit Keithley 2002 returned back to xDevs.com lab once again for the second calibration testing. This is the same meter repaired in 2023 during the previous CalFest. It was working happily at LC lab since then and now it’s time to check it’s health again.

p=.

p=.

Previous report is available here:

Calibration report for Keithley 2002, as adjusted and returned, 24 hr spec, April 9 2023

New report generated by xDevs.com calkit, with calibration only prior to any adjustments.

Calibration report for Keithley 2002, as received, no adjustments, 24 hr spec, August 29 2024

It is no big surprise that Keithley 2002 is unable to meet it’s 24 hours specifications without adjustment after 508 days. But no major deviations were observed with worst point being only 190% of the spec for negative 2V fullscale test point.

Next step is to proceed with adjustment and recalibrate. This should bring the instrument back to 24 hours specification with good margin again.

Calibration report for Keithley 2002, as adjusted to 24 hr spec, September 6 2024

Conclusion and future plans

This year CalFest was a blast once again with special guests and additional side activities. Visit to TheSignalPath amazing lab was also highlight of the meetup week and had great deal of fun and excellent opportunity to discuss aspects of today’s technology in person, various measurement methods, used test equipment market and RF technology. Shahriar proved once again his excellent insight knowledge of electronics design, test equipment and managed to quickly troubleshoot projects. :) Hopefully I can also extend the collaboration with return visit in future for more interesting projects.

As for CalFest 2024, it’s core idea remains the same: bring electronics and test equipment enthusiasts together and share the precision calibration projects among members in Canada and USA. We would love to include other geography members too, but logistically it’s already quite a challenge, considering that this is not a sponsored or business funded activity but a free time self-funded enterprise for all of the participants.