by Hale Farley
This story was published in the November 2012 Tektronix Retiree News and has been edited for minor errors.
The following write-up on the introduction of the R7912 Programmable Transient Waveform Digitizer was prepared by Hale R. Farley who worked at Tektronix from for several years. The R7912 and its replacements, the 7912AD and the 7912HB, appeared in Tektronix Products catalogs from 1975 to 1989.
This is a brief history of the development of a unique product from Tektronix. The market place had been requesting a method to capture single transient phenomena into a digital format for computer analysis. During the late 1960's a scientist from Tektronix Labs, Carlo Infante, proposed developing such a product. Infante wanted to use the oscilloscope deflection technique (3-gigahertz analog bandwidth similar to a 519 oscilloscope) to write a beam on a storage target and scan this storage target using a video scan. The result of this effort was a dual-gun scan converter whose output could either be a video display or a digital data stream representing the signal.
Once the dual-gun scan converter was a reality, John Gates, engineering manager, assigned Jim Cavoretto to form a group to complete the task of making an instrument. His group developed the electronic circuitry necessary to take the signal from the diode array storage target and process it into a signal, which could be displayed. Although the signal from the diode array storage target was small (about 9 nanoamps) it was sufficient to be amplified above the noise level of amplifiers. The analog to digital flash converter would acquire 512 samples of the signal on the screen, so using a 7B92 with a maximum sweep speed of 500 ps/div, the sample rate was astonishing 100 GSa/s.
In March 1973 Bob Hightower, a field engineer in the Albuquerque Field office, brought a prototype of the R7912 into Sandia National Laboratory where I (Hale) was doing laser fusion experiments under the direction of Dr. Gilbert L Cano. “We were using a mode-locked laser beam (a sister to the laser from America Optics developed for lunar ranging test at NASA) to focus high energy into a deuterium foil and look at the energy released. This lab was in a warehouse, which did not have very good temperature control; thus it was difficult to keep the optics in good alignment. Using oscilloscopes like the 7904 and taking pictures of the trace was a very time consuming process thus only three or four events could be recorded in a day. We had recently purchased a large number of R7903s for this program. The raster scan display of the R7912 allowed me to keep the optics aligned in real time. Hightower was asked to join a marketing group in Beaverton Oregon run by Bob LeBurn for transient recording and signal processing.
Hightower invited me to interview in June and asked me to join his team in late July thus began my career at Tektronix. In August 1973 I became the “front man” for introducing the R7912 to the world. An electronic trade show (Northeast Electronic Show) was being held in New York City in late September. It was decided by Hightower and Leburn to show the R7912 at the trade show as well as the Nuclear Science Symposium a week later at the Sharon Palace Hotel in San Francisco, California.
Because of the upcoming events I needed to come up to speed in transient recording in less than six weeks. The show setup was to consist of a computer (DEC 11/23 with magnetic tape drive and magnetic memory), R7912, display (4010), video monitor, thermal printer (4610), and WDI Tek basic software. A laser was used as a light source for display purposes.
One of the first people who saw the show setup was President Howard Vollum. He asked several pointed questions, particularly about laser measurement and underground nuclear testing. The following week, in San Francisco, one of the people to view the setup was Walter LeCroy of LeCroy Research. LeCroy Research had a solid state digitizer 20 points at 10 nanosecond interval. Upon seeing the R7912 Walter LeCroy realized the market for his digitizer would be limited. His hairless head turned red with anger!
Major markets for the R7912 were nuclear testing, EMP simulation, laser measurements, and florescence decay in chemical process in plants. The R7912 continued to be a leading edge product for more than 35 years. Production of the R7912 ceased when the diode array storage target was no longer made. Although about 40 years have passed, to my knowledge there is still not an instrument, which surpasses the dynamic range and digital resolution of the R7912. In my professional life there are no events, which surpass the excitement of the marketing assignment of introducing the R7912.