[time-nuts] 75Z vs 50Z for GPS receivers
didier at cox.net
Mon Feb 5 23:43:13 EST 2007
I am familiar with the Jim Williams app note, but I felt the pulse shape
was somewhat lousy (based on the pictures that came with the article)
due to the very small cap on the collector, OK to calibrate or evaluate
a fast scope, I guess, but too far from a square wave to be able to
visually observe and analyze reflections (at least from my perspective).
Due to my ignorance of the avalanche effect, I did not think of mating
this with a delay line. It seems the Zetex app note with a delay line
can make decent square pulses, I have to try that. I have made high
power pulse generators with delay lines a long time ago (radar
modulators), it's been so long I had forgotten...
Brooke Clarke wrote:
> Hi Didiere:
> There's also an app note at Linear Technology for making pulses so fast
> they are used to calibrate sampling scopes.
> Some years ago I made a very simple circuit that pulses a LED with many
> amps (very short time) based on a transistor going into avalanche.
> Have Fun,
> Brooke Clarke
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