Re: In Defense of the 7A19


Thanks Dennis,
I just love this kind of background stuff! This helps us all understand how technology, design, business and marketing intertwine.

Great stuff!


Sent from the planet Zarnok

On May 29, 2020, at 3:23 PM, Dennis Tillman W7pF <@Dennis_Tillman_W7pF> wrote:

´╗┐In a recent post the 7A29 was recommended as a much better plugin that the 7A19 which apparently has a poor reputation among members of TekScopes.
I don't disagree with that assessment. But if you know a few of the details behind its remarkable development and its strategic importance to Tek you might appreciate it more.

Tek was always known for how much attention they paid to the "Human Factors" of their products. Howard Vollum's goals for the 7000 series forced the "Human Factors" engineers to get much more creative. The result was a totally new look in scopes. In 1969 Tek introduced their brand new 7000 series lab scopes at the 1969 WESCON industry trade show in San Francisco. Tek's new top of the line 150MHz 7704 was 3 times faster than their current 547 lab scope. Tek was justifiably proud of the 7000 series. Here are a few examples of the new features Tek was so proud of:
* The new triggering control (one of Howard's requirements) combined the level and slope into one knob can turn through 360 degrees. This made it possible to trigger anywhere on a waveform while the knob showed the corresponding level and slope of the trigger point.
* The Tek 7704 had 4 plugin slots for much greater flexibility. It could display up to 4 signals simultaneously at two different sweep speeds.
* The new scopes had lighted push buttons to make them easier to use.
At the same show HP introduced their new line of lab scopes. But it quickly became apparent that the new HP scopes were superior in many ways. Here are two features that proved to HP that they had the superior products:
* The new HP scopes had much better specifications and they cost much less than the 7000 scopes.
* When you applied an AC signal that went from low frequency up to the limit of the scopes triggering capability the HP scope triggered perfectly across the entire frequency range without ever missing a trigger point. By comparison the 7000 trigger setting had to be constantly adjusted to get it to trigger. HPs triggering capability was so good it left Tek embarrassed by their trigger circuits.

HP wasted no time touting the superior performance and lower cost of their new lab scopes with an industry wide advertisement. Within Tek this became known as the HP "Foxtail" ad. It didn't mention Tek but it mocked the new features of the 7K scopes as irrelevant "bells and whistles". One of those bells and whistles was Barrie Gilbert's revolutionary on-screen readout.
I uploaded this ad to TekScopes at

Internally the WESCON show was described as a big success to the Tek employees. But Howard Vollum and the rest of management knew they were in trouble. The 7K introduction was a flop. What Tek did next would cement their reputation as the industry leader in oscilloscopes for decades to come.
The ultimate goal of the 7000 series was never meant to be the 150 MHz 7704 that was introduced at WESCON. The 7000 series was designed from the beginning to have the capability to go much faster. But faster scopes could not be done with discrete parts. Tek would have to develop their own 1GHz+ analog IC process to make faster scopes. That would be extremely difficult. Meanwhile the 7000 design team was working on the next mainframe scope and plugins to leapfrog HP. The 7704 was 3X faster than the previous 547 50MHz lab scope. The next scope was going to be 10X faster if they could do it.

Thor Hallen, an excellent vertical amplifier designer was given the task of creating a vertical amplifier with 500MHz performance in the 7904. That meant his design had to have a standalone bandwidth in excess of 700MHz. The amplifier was required to use the new ICs Tek was making. Thor had less than 2 1/2 years to do this. When the date was decided for the announcement Tek still couldn't make the ICs Thor was supposed to use to achieve the unheard of specs the 7A19 had to meet. The ICs were nowhere to be seen. At the last minute Thor had to substitute discrete transistors for the ICs and still make it work at 500MHz in the 7904 it would be announced with. I have that 7A19 plugin in my collection that Thor made, with the transistors Thor used, for the announcement. As if that wasn't enough, all by himself, Thor designed the 7A19 Option 4 plugin which has variable delay so two extremely fast signals can be displayed at the same point in time on the CRT. The 7A19/7A19 Opt 4/7B90/7934 combination was the fastest lab scope ever made and it was ahead of its time in 1972.

In spite of the inferior performance of the 7000 products Tek announced at WESCON 3 years earlier, engineers liked what they saw and wanted features like on-screen readout. Ironically the bells and whistles HP mocked in the Fox Tail" ad were a strong selling point for the new 7000 series. By the time Tek introduced the 7904, HP was no longer crowing about their superiority in scopes. The development of the 7A19 and 7A19 Opt 4 by Thor Hallen is an astounding achievement for 1972. Its 500MHz performance in the also astounding 7904 lab scope was so much faster than anything else at the time that Tek reclaimed the crown as the undisputed leader in oscilloscopes. They kept the crown for over 20 years after that.

Dennis Tillman W7pF

Dennis Tillman W7pF
TekScopes Moderator

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