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RE: Scoping out 'scopes
To: CRTech <crtech@crtech.org>
Subject: RE: Scoping out 'scopes
From: Alan Kilgore <wrvm.engineer@gmail.com>
Date: Mon, 11 Dec 2017 14:43:22 -0600
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In-reply-to: <0MSbFy-1eW5qP30hI-00RdIr@mrelay.perfora.net>
References: <b4312a76-e85a-2276-fa59-57742ac184fc@wb8zcc.com> <0MSbFy-1eW5qP30hI-00RdIr@mrelay.perfora.net>
Multiple input scopes usually display the channels (inputs) on the same screen by chopping the time base for dividing the time among the inputs being displayed. You can usually see this effect when you turn the sweep to the fastest rate. That's why there is an issue when using a scope near the top end of its sweep rate.

Another method is to take turns with each channel. So instead of chopping the entire time of a screen sweep into itty bitty pieces, the entire sweep is made for channel 1 then the second sweep is displayed for channel 2. etc. That avoids the choppy appearance when using sweep rates near the top end. However, when zooming in on the time domain, you usually want to compare the channels displaying the same time frame instead of with time delays between each channel.

Everything is a trade-off in engineering.
Alan Kilgore, CPBE
WRVM Chief Engineer

At 03:00 PM 12/11/2017, you wrote:
More expensive one sure looked like 4 inputs but they must be switched or something ?

From: Russ Hines [mailto:russ@wb8zcc.com]

That's true, and I believe that's the case with both the Siglent and the Instek mentioned. So if you really need a hyper-critical piece of test equipment, maybe these aren't the 'droids you're looking for. But as a general troubleshooting aid, I've found the Siglent to be just dandy.

Russ Hines
JMS & Associates, Inc.
Reply to: russ@wb8zcc.com
On 12/11/2017 13:01, Nathaniel Steele wrote:

Some of those low end scopes share thatvresolution amongst all channels. So 1GS/s on one channel but 500MS/s if using two and 250 MS/s using 4.....

Not sure about either of those scopes in particular but it is something to watch out for.

References: Re: Scoping out 'scopes
(Russ Hines <russ@wb8zcc.com>, 11 Dec 2017 18:46:42 -0000)
RE: Scoping out 'scopes
("Wiely Boswell" <wiely@faithradio.org>, 11 Dec 2017 20:23:41 -0000)
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