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How good is your scope? (problem with capturing offset signals)

I'm surprised at the Agilent... that's ridiculous. Using something like your test waveform (100 kHz, 10V pk-pk, DC offset = 6V), all three DSOs within reach did reasonably well. On my MSO6054A (the one I will take with me to Hell to hack the HVAC controller), the base of the waveform at ~1V was visible and accurate down to 500 mV/div, but could not be brought back onscreen at 200 mV/div. It actually looked good down to 200 mV/div on a DSO3062A (rebadged Rigol), and likewise for the old Tek 2430A.

No complaints, they performed about as I'd expected... except that I figured the $200 Rigol would have dropped the ball as soon as the waveform went offscreen. I don't expect commodity DSOs to ship with

7A13 front ends, so that TDS3032B is pretty impressive.

-- john, KE5FX

Reply to
John Miles, KE5FX
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[snip]

I was going to ask the AC vs DC thing as well. I don't see an obvious indication of this setting for either trace.

But I'm always suspicious about a trace that runs off the top (or bottom) of a scale significantly. One really has to know how one's scope handles over range inputs.

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Eagles may soar, but weasels don't get sucked into jet engines.
Reply to
Paul Hovnanian P.E.

Don't hold your breath :-)

-- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

Reply to
Fred Abse

The photos look similar to an instrument we had demonstrated a while ago. As soon as the guys saw "My Scope" on screen, they howled with laughter, and most just walked out. The Tek rep beat a hasty retreat, never to be seen again.

Seems that a 770X or 790X with a couple of 7A13s in it would suit Klaus.

I have two 7905s, a 7905A, a 7105, in daily use, with a 7705A in reserve. All the extenders and calibration fixtures, too.

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)
Reply to
Fred Abse

Do they teach analog engineering any more?

Most, if not all analog engineers I know, including, I believe, those who inhabit this NG, are well into middle age and beyond.

The modern approach seems to be to throw lots of software into mediocre hardware.

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)
Reply to
Fred Abse

Sort of, but you can't learn it sitting in an auditorium. It needs to be lived, and that's hardly happening anymore.

Yup, that's the Western way, it seems. In Asia it seems the other way around at times. Well, obviously not with some scopes. Anyhow, I got this Chinese arb generator from a company I never heard of, that isn't even found on the web. First one was bad. Finally I got a new one and it works great. Can do stuff that many gens 4x its price can't do. The software and manual? Full of spelling bugs and stuff ... but ... it works :-)

--
Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

Reminds me of a manual written by compatriots of yours that I once read:

"Manufactured with a pure technic"

WTF does that mean?

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)
Reply to
Fred Abse

Don't have the foggiest. Maybe it relates to the German purity law for beer.

I emm out off zee Rrreinlannd ... :-)

--
Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

Its DC coupling. Even if it was ac, the input would still be overdriven, and if I use ac, then I cannot "see" the details at GND, since it will be shifted away

Reply to
Klaus Kragelund

I have a 20mhz Ab Rigol that just seems to work perfectly. Not bad for chinese junk.

Jamie

Reply to
Jamie

Nothing. The technical term for the above phrasing is "sales jargon" or "marketing buzzwords." ;-)

Hope This Helps! Rich (or marketing jargon, or sales buzzwords - mix and/or match to taste.)

Reply to
Rich Grise

I like the old term "bafflegab" :-)

--
Dave Platt                                    AE6EO
Friends of Jade Warrior home page:  http://www.radagast.org/jade-warrior
  I do _not_ wish to receive unsolicited commercial email, and I will
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Reply to
Dave Platt

How far will it let you window more than one screen height?

I wouldn't have thought there would be much market for

Reply to
Fred Abse

It was in a service manual for some German kit. Translated from the deutsch by some non=technical minion, probably. This was before the days of computer translation, and all that jazz,

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)
Reply to
Fred Abse

Reply to
Joerg

Yes, they are all different. It's too bad that no efforts are made to specify this behavior in the specs. But admittedly, this would be challenging.

--
_____________________
Mr.CRC
crobcBOGUS@REMOVETHISsbcglobal.net
SuSE 10.3 Linux 2.6.22.17
Reply to
Mr.CRC

Specification of a Tek 7A13 vertical amplifier plugin manages to specify this behavior:

Maximum input voltage, (DC direct coupled) at each input attenuator setting.

Not challenging to specify, but they were proud of this particular aspect of performance, not, as I suspect most modern manufacturers are, ashamed of it.

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)
Reply to
Fred Abse

h
o

fy

=A0 =A0(Richard Feynman)

The Tek 7A26S module Joerg spoke of, has a definition of maximum 75 times overdrive. Quite good, but the overdrive takes 100us to recover (worst case specs)

As for the Tek DPO 5000, I dug deeper into it, and found that the majority of the problem (guess 70%) is actually from the TPP0500 probe. A test with a P6139 probe provided much better results. We are returning those TPP0500 probes for sure...

Regards

Klaus

Reply to
Klaus Kragelund

I don't know why they wrote that. Maybe those dreaded lawsuits came up in the 70's and they didn't want exposure :-)

So I just tried it out with the 7A26 here. Put a 50MHz square wave in it, then cranked it up to over 100x overdrive. No noticeable recovery time at all.

Strange. How can a passive probe do that?

--
Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

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=A0 =A0 =A0(Richard Feynman)

The datasheet lists it as a passive probe, but it is supplied with power, probably for some relays and other gimmicks they have inside the probe. When Volt/div is changed clicking can be heard, so its probably not a 100% passive probe, only it does not have an amplifier per se.....

Regards

Klaus

Reply to
Klaus Kragelund

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