--- In TekScopes@..., "Craig Sawyers" <c.sawyers@...> wrote:
Subject: [TekScopes] Type 111 Pretrigger Pulse Generator not
up to speed
I finally got around to replacing the caps in my Type 111 (s/n 490)
and find that it is not as fast as advertised; it's around 790pS,
where i had expected <=500pS.
Trying to deconvolve a fast rise time from a longer one is fraught with
problems. 500ps on a 1ns instrument response is a nominal 1.12ns - which is
only 14% different from your measured 1.275ns. Are you sure your timebase
is that accurate on the fastest sweep ranges (they often aren't).
I've got a chicken-and-egg problem here. I have a pile of 560-type sampling plugins that
I want to fix up, and need to get the 111 going to help do that :) Right now I'm borrowing
time on a modern Tek TDS4000 series. 350MHz digital phosphor unit. I have heard that
the frequency response of the recent digital scopes is not guassian - that the rise time is
somewhat faster than bandwidth alone would indicate. That makes me think that my
estimate of 111 risetime is actually erring on the high side.
Mostly I'm just glad it works at all, actually, I shouldn't complain too hard. I suppose the
3S gear and the 111 can bootstrap themselves up to speed, one step at a time.
