Tektronix organized a scope class in the early 1950s. Participants would include service and manufacturing engineers and they would design and manufacture their own oscilloscope. This scope class would help enable new ideas, concepts, and circuits for scope designs to be tried out and evaluated and it would also indicate resources elsewhere in the company that could be better utilized in design engineering. John Kobbe describes the Scope Class in his story "My Early Tektronix Days" on the Employee Stories page.
With Tek’s blessings, a group of five or six of us formed a scope class to design and build an oscilloscope. We would not copy anything and keep it as simple as we could. A month or so on, we had the vertical system, horizontal amplifier, and CRT circuits (except the unblanking). The vertical was to have a 10-1 variable gain, 10 times and 100 times attenuator, no signal delay line with about 3 or 4 MHz band width.
We were having problems figuring out a simple time base (sweep) circuit. On a coffee break I cornered Dick Ropiquet, who had just finished a wide range sweep for the 315 scope, he described all the functions of an idealized sweep circuit. The 315 sweep was more complicated than what we wanted to use, so I set out to find a simple way to keep all the needed requirements but kept coming to dead ends. Finally a circuit made all the way around the loop and was simple enough for our scope.
The scope class was fairly well known within the company. Sandy Sanford and his secretary had their desk just through a door on the other side of the wall from my bench. One of Sandy’s job was to take care of field technical problems. When he didn't have an answer, it was easy for him to step through the door and discuss the problems with us. One of the common problems was the intensity (brightness) needed adjusting after a duty cycle change. Not too bad if it got brighter but when it disappeared the customer would sometimes get totally lost. The unblanking not only needed to be solved for our scope class but for Tek’s new designs. I decided to start a list of all different ways I could think of and adding to the list for the next week or so, then picked the one that looked most promising which was the floating power supply. The first thought was that it was too complicated, but when you look at how it is done, it isn't really that bad.
I came in early one morning and put together needed circuitry, hanging it out the side (so it would be easy to put back to normal) of an upside down scope which I was supposed to be calibrating. Went into engineering, explained the idea and like my first thoughts, they were doubtful. When they found out that there was one hay-wired together on my bench, Frank Hood said he would come look at it, as he needed a better unblanking system for a new portable scope ( would be called the 310). He liked what he saw and thought that some more engineers should come look at it. Frank also wanted our sweep for his new scope.
I soon found myself in engineering and the scope class came to an end, but I guess you could say it sort of lives on as a 310.
The museum has a scope class oscilloscope. We have no information as to who the designer was nor any documentation or schematics. It is designed and built in two chassis, one for the power supply and one for the oscilloscope.
Our restoration engineer Phil Crosby has been working to bring this oscilloscope back to life. This photo shows the first waveform on this oscilloscope in 65 years! Nice work, Phil.
The front legends are hand-drawn and faint. This photo shows what the various controls and settings are.