Patent US 2883619A
|Patent number||US 2883619A|
|Inventors||John Kobbe, Bill Polits|
The 10th Tektronix patent, this is the famous invention of using lossy coax cable (a resistive center conductor) in a passive probe to dampen reflections and ringing.
John Kobbe said:
Another anticipated problem with passive probe, we knew a signal bounced back and forth so we could not use the standard probe.
While thinking about things to do like some damping resistors. Why not us a fine resistance wire as the center conductor.
This time we really lucked out, it worked better than anticipated. It was even patent-able as was unblanking and [the] sweep circuit.
Until the early 1970s, Tektronix manufactured lossy coax cable in-house using repurposed shoelace weaving machines: https://vintagetek.org/june-photo-of-the-month-coax-cable-production/