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Welcome Welcome to my redesigned site documenting vintage electronics restoration, vacuum tube audio and radio repair, and the history of technology. Here I share hands‑on projects, repair walkthroughs, historical research, and high‑resolution photos from my bench. Relaunch note I’m rebuilding the site from the ground up to replace ageing, hard‑to‑maintain code with a cleaner, more…
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The Roetest Tube Tester stands out as one of the most capable and thoughtfully engineered modern instruments available to anyone working with vacuum tubes. Designed by Helmut Weigl, it bridges the gap between classic tube‑era test gear and contemporary measurement practice: fully automated, PC‑connected, and able to characterize tubes with a level of precision that…
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As of this writing (May 2026) AI Assisted Coding is it’s infancy. However the tools are available and very competent, given proper direction. Over the past few weeks, I have used Claude Code to help write control, logging and calibration applications for the following instruments: My goal as I approached this was to come up…
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The Hewlett‑Packard Z3815A is a GPS‑disciplined frequency reference originally designed for telecom‑grade timing applications, but today it has become a prized instrument among precision‑timing hobbyists, metrology labs, and the broader time‑nuts community. At its core, the Z3815A combines a high‑stability E1938A “hockey‑puck” oven‑controlled crystal oscillator (OCXO) with a robust GPS receiver subsystem, allowing it to…
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In a recent post, I documented the replacement of a difficult to read VFD display with a modern TFT display in my Advantest R6581T. It was unequivocally worthwhile and has been working extremely well. Nowl, I am at it again, but his time the subjects are the HP 3478A 51/2 digits DMM and the HP…
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The Advantest R6581T is an 8.5‑digit, rack‑mount digital voltmeter (DVM) built for high‑precision DC measurements; the T variant is a DC‑only field/rack model (no AC TrueRMS option) and is prized on the used market for lab and calibration work—buyers should expect to source units secondhand and verify display/health before purchase. Overview Notable Features and Design…
Shaun Merrigan
Classic Electronic Restoration, Vacuum Tube Audio, Technical History, Photography