Archive for May 2018

Keithley 775A Programmable Counter Teardown

I just picked up a Keithley 775A programmable frequency counter from eBay. Specification-wise, this counter is very similar to the Racal Dana 1992 frequency counter I repaired last year. The Keithley 775A I got came with an additional channel (option 7751) and is capable of measuring frequencies up to 1.3 GHz. Continue reading ‘Keithley 775A Programmable Counter Teardown’ »

Teardown of a GM3120 Electromagnetic Radiation Tester

There are a lot of cheap electromagnetic radiation testers out there which boast some quite impressive claims. So I decided to pick up a popular one (GM3120) from eBay to see how well it works. And perhaps more importantly, I wanted to take a look inside to see how the E field and H field sensing is done. Continue reading ‘Teardown of a GM3120 Electromagnetic Radiation Tester’ »

HP 8566B Spectrum Analyzer “YTO Unlock” Repair

While I was making a video on how to use HP 8671A as the frequency reference for an improved version of my simple DIY tracking generator for my HP 8566B spectrum analyzer, my spectrum analyzer suddenly decided to call it quits and displayed the dreaded “YTO Unlock” message. Although it wasn’t the first time it had done so — other times the “YTO Unlock” message only appeared once in a blue moon and rarely affected any measurements — this time however the problem seemed to be permanent and the error message wouldn’t go away. Continue reading ‘HP 8566B Spectrum Analyzer “YTO Unlock” Repair’ »