Vintage Test Instruments

My vintage test instrument collection is predominatly HP, with a few Tektronix and others mixed in. They are mostly rather high end instruments, with a bend on RF/microwave. When I get the instruments, as gifts, off eBay or lab rejects, they usually don't work. Or if they do, they fail shortly thereafter. Not to worry, I always get them to work. The repairs are chronicled on the CuriousMarc YouTube channel. Here you will find more detailed info and links supplementing the videos.

This section is under construction and many projects don't link to any page yet. The ones that do are at the top of the list. If you need some info about a particular item, just let me know , that's usually a good incentive for me to write up the page about the instrument and post the documentation.

PROM Programmer

It was the king of PROM programming at the time. Mine (from eBay) needed a lot of TLC. But it's still the King.

Liquid Level Meter and Controller with Capacitive Probing

This unusual 1970's instrument is a surplus store find. It was initially reversed engineered and repaired thanks to its patents, but we later were able to get in touch with inventor George Rauchwerger, who was super helpful and gave us a copy of the original manual.

1.3GHz Tracking Generator for the HP 8568

This is the special version of the HP 8444A that works as a tracking generator for the HP 8568.

1.5GHz RF Spectrum Analyzer

My HP 8568 has the dreaded YTO unlocked error.

1ns Rise Time Pulse Generator

This awesome pulse generator had many faults, one of which necessitated to remake an replacement for a failed ECL IC.

10KHz-1280 MHz Synthesized Signal Generator

My 8662A, the fabled gold standard of synthesized low-noice oscillator, is in trouble. Let's fix it.

26.5GHz tracker for the HP 8566

Although I had previously made my own homebrew 2.5GHz tracker for the HP 8566, I eventually bought the real thing that covers the whole band and then some. Which promptly failed on me, and led to quite a switching power supply repair adventure.

Wide Bandwidth Oscilloscope Repair

This is the vintage 'scope and repair that began the collection. This is a legendary and famously expensive instrument. This is the first scope capable of 10 GHz bandwidth that I ever laid my hands on, at the beginning of my career at Bell Labs in the early 1990's.

The following pages have not been completed yet. In the meantime, they just link to the corresponding video or playlist. Contact me if you need more info about the following restorations, that might give me enough incentive to complete the page!

100Hz - 2.5GHz tracker

I hack an HP 83522A plug in to transform it into a low-band tracker for the HP 8566B up to 2.5 GHz.


An early, specialized logic analyzer for HP-IB bus sniffing and debug. It allowed me to reverse engineer my HP 7970E tape drive complicated sequence of commands.


With this one, you literally see the ones and zeroes! Made to generate a vector display on an X-Y oscilloscope, this is one of the very first logic analyzers from HP. With about zero memory, but more features than you'd think.


An oldie but goodie, this 10 Mhz-1.3GHz dual amplifier has gorgeous ceramic hybrid RF amplifiers inside.

Bought for cheap at an auction, this very useful instrument sure did not work at first.

A classic instrument, suffering from a classic failure.