[sdiy] Simple Scope Question

[Magnus Danielson]

From: harrybissell <harrybissell at prodigy.net>
Subject: Re: [sdiy] Simple Scope Question
Date: Sat, 22 Jan 2005 11:05:57 -0800
Message-ID: <41F2A415.5A9F53E4 at prodigy.net>

Hej Hårige Harry!

(annother word for Harry to learn and decrypt)

> Magnus Danielson wrote:   (hej Magnus :^)
> 
> > OK, let's just say that the chop I've seen been not very usefull since they
> > have been at too low frequencies and that ain't usefull. So, what I meant to
> > say was that chop is usefull when it runs at sufficiently high frequency.
> > However, I don't recall the chop-frequency being listed anywhere, so it is hard
> > to give general advice about it.
> 
> ahh thats better.  I agree that most scopes do not show the point where the
> 'chop' strategy is abandoned...and it switches automatically to 'alt'.

It? You I'd assume. You are talking too modern scopes here! Plain old analogue
scopes where the AutoSet button is in the users nerve-system and not in the
scope itself. I am talking the kind of gear that most beginners is probably
going to be able to get for a fair amount of money. Many of those scopes have
really bad chop-operation I am sad to say. This is why I made the statement
that I did. For analogue scopes chop-operation severly limits the bandwidth in
the chop mode, since the bandwidth behind the chop-multiplexer with smooth the
signal out if a too high chop frequency is used and the chop frequency is in
itself limiting the bandwidth of the involved signals.

> Usually you can tell, and again... agreed that 'alt' is appropriate for high
> frequencies where (possibly) events are more repetitive and 'one-shot'

Indeed.

> I'm usually looking for transient, non repetitive events. My favorite scope
> is a four channel Fluke/Philips 100MHz four channel Analog/Digital.  Does it
> all   :^P

Well, that's a deluxe scope for a beginner.

I have a Tek 11402 digital scope with 4x300 MHz BW, 2x400 MHz BW and 1x1GHz BW
modules in it. That's 7 channels, touch-screen, high linearity and time-
resolution down to 10 ps between samples. It's not your average beginners
scope. I'd like my Tek 547 with 4-channel module scope back. It's a lovely
scope. My main problem is space... and then I am not complaining since I know
what a Tek 555 implies in space and weight!

Oh, if someone has a spare 11A72 module around, please let me know!

Cheers,
Magnus