Re: 11403A as bench scope, how useful is it?

 

Hi,

You are taking Nyquist too literally. If all you had was one chance to
sample a waveform the Nyquist Criteria would apply but if the waveform is
repetitive then you have an infinite amount of time to sample it or to build
up a set of samples. This is like the difference between a waveform that is
a single shot or a waveform that repeats.

These were the early days of digital scopes and many clever schemes were
needed to achieve excellent bandwidth (1GHz to 3Ghz) with the relatively
slow sampling speed available in those days. The 11403A is capable of GHz
bandwidth on several channels as long as you are measuring repetitive
signals.

A single shot waveform only gives you one chance to sample it (or one chance
to display it on the CRT of an analog scope). Your eye has to be really fast
to see the entire one shot waveform or to study any part in detail. A
repetitive waveform refreshes the phosphor of the CRT over and over and you
eye has a chance to study any part of it in detail for as long as you like.

Dennis Tillman W7PF

-----Original Message-----
Sent: Tuesday, June 20, 2017 2:00 PM
Subject: [TekScopes] Re: 11403A as bench scope, how useful is it?

The biggest weak spot is the 20MSPS maximum sample rate. The short
record length is not so great either.

Is it really that low? Wow.
Using my typical rules of thumb that gives you a good look at square
waves up to about 2MHz (5th harmonic is 10MHz, Nyquist rate -> 20MSPS).

Not great at all. Surely it has some tricks to be better for non
repetitive signals?
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Posted by: cwilkson@...
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