Re: worst condition Tektronix scope?


Hi Jeff,

See my embedded responses.

On Fri, Nov 27, 2020 at 03:02 AM, Jeff Dutky wrote:

It's a shame that Tek did not make a range of plugins for the 465M. It looks
like it's a lot nicer to work on than the 465/475. I wonder why they didn't
pursue that avenue of development. There is no mention of other plugin modules
for the 455 either, but that TekWiki page appears to be almost a stub.
I've sometimes wondered what the technical differences between the central modules of 455 and the 465M were but didn't bother to investigate. I only have a 455, no 465M.
I'm not sure what plugins would be possible and make sense for the 455/465M mainframe(s) but then I'm spoiled by the 7000 family. Besides, I'm sure one would have difficulty configuring the 'scope with the modules needed in preparation for on-site use, the main (intended) environment for a portable 'scope.

I'm curious about how the analog storage scopes like the 466 were used. Were
you able to get a snapshot of a single wave form? Or did this just capture a
persistent image of the repeating signal that we can see on a non-storage
The 466 is eminently suited to doing exactly what you're suggesting, much more so than even a 464. With a 466 it's quite possible e.g. to store and then observe an edge with a rise time of 3.5 ns (the fastest for the 100 MHz BW), either in Variable Persistence (repeating at say 1 Hz) or Fast Storage (single shot) mode. Compare that with trying to view it on a 'scope like the 465, or for that matter, a 475. Unless the signal has a repetition rate of at least 10 to 100 kHz, it'll be completely invisible!
That's why I love my analog storage 'scopes, at least until I pull out a reasonably modern DSO...

I remember my father using the 475 to debug minicomputer hardware. His
method involved setting the machine in a tight loop that exercised the suspect
part or function, then observing the repeated signal with the scope. Now you
would just use a DSO to capture a few microseconds of signal to memory and
wander through it at your leisure, but such a thing would have been
prohibitively expensive in 1978.
One way was using an Analog Storage 'scope as above, using the delayed time base to move the observable (B-trace) window by adjusting the delay time, until either signal- or delay time-jitter spoiled the fun. A next-level procedure in many cases then would be using the delayed time base not in the common "Runs After Delay" mode but in the "Triggerable After Delay" mode.
In those days, the operator controlled the tools, not vice versa...


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