Tektronix pushed the limits of electronics and devices to deliver leading-edge instruments.  A good example of this is the 7612 digitizer.  The 7612 has a vertical bandwidth of 80 MHz with a sample rate of 200 Msamples.  High performance semiconductor ADC (analog to digital converter)  solutions were not available so Tektronix designed their own.  Their solution was a hybrid CRT-semiconductor converter tube, the T7610.

The precision analog portion of the converter was a CRT tube which generated a wide "ribbon" beam.  The digital portion of the converter was a semiconductor chip of an array of diodes organized in rows to product a gray code output.  In simple terms, the ribbon beam would charge a single row of diodes which would then be read out.  Only Tektronix would bombard semiconductors with an electron beam.

The museum does not have a 7612 digitizer but does have a T7610 CRT.  Click on the CRT image to view it in higher resolution.

This view shows the custom semiconductor circuitry on the end of the CRT.

The museum also has a small quantity of the T7610 diode array chips.

There is also a video of the T7610 tube on YouTube


The Tektronix Concept Training book Cathode Ray Tubes: Getting Down To Basics has a detailed chapter on the operation of this tube called "Special CRTS: 7612D Electron Bombarded Semiconductor Tube for High-Speed Analog-Digital Conversion".  The content of this chapter was also published in a SID (Society for Information Display) paper by Ray Hayes and Mel Balsinger (Proceedings of SID, Vol 20/2, Second Quarter, 1979. Click on the image to view the PDF of the Tektronix chapter.