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Tek 2430A - please tell me it's a good scope... :]

Marcin Marzeta
 

Dear Group,

My first post here. I'm in Poland and I design and build tube guitar amps.
I currently own a reliable 7603 and have recently started fixing my old 465 with DM44.

Yesterday I snapped and bought a 2430A. I think I really need built-in measurements as they make life easier. The problem is I'm not sure if I made a good choice... 2430A I bought looks fully working with all originall manuals and even probes, very good condition. So I'm actually looking for a general opinion on the model - is it a good one?

--
Marcin
marvelamps.com / 465 DM44 / 7603 / 2430A (on its way)

Harvey White
 

On Tue, 13 Feb 2018 07:02:45 -0800, you wrote:

Dear Group,

My first post here. I'm in Poland and I design and build tube guitar amps.
I currently own a reliable 7603 and have recently started fixing my old 465 with DM44.

Yesterday I snapped and bought a 2430A. I think I really need built-in measurements as they make life easier. The problem is I'm not sure if I made a good choice... 2430A I bought looks fully working with all originall manuals and even probes, very good condition. So I'm actually looking for a general opinion on the model - is it a good one?
I have one and I like it. Nice portable scope. Bandwidth should be
fine for what you do.

Harvey

Vince Vielhaber
 

I have two of them. I like them both.

Vince.

On 02/13/2018 10:02 AM, Marcin Marzeta wrote:
Dear Group,

My first post here. I'm in Poland and I design and build tube guitar amps.
I currently own a reliable 7603 and have recently started fixing my old 465 with DM44.

Yesterday I snapped and bought a 2430A. I think I really need built-in measurements as they make life easier. The problem is I'm not sure if I made a good choice... 2430A I bought looks fully working with all originall manuals and even probes, very good condition. So I'm actually looking for a general opinion on the model - is it a good one?

cmjones01
 

On Tue, Feb 13, 2018 at 10:01 am, Marcin Marzeta wrote:
My first post here. I'm in Poland and I design and build tube guitar amps.
Welcome. I'm also in Poland though I don't design and build guitar amps :-)

Yesterday I snapped and bought a 2430A. I think I really need built-in
measurements as they make life easier. The problem is I'm not sure if I made a
good choice... 2430A I bought looks fully working with all originall manuals
and even probes, very good condition. So I'm actually looking for a general
opinion on the model - is it a good one?
It was a pretty decent portable digital scope in the early 1990s. I have one too which I still use regularly. I like it because it drives like the 2465 analogue scopes I'm used to, and because the first ever digital scope I used as an apprentice was a 2430. I remember having to ask special permission to get it out of a locked cupboard and use it. Now I have my own I don't have to ask anyone!

Even cheap modern digital scopes will beat it on the kind of specs that get obsessed over in some fora (record length, number of waveforms per second, that sort of thing). However, those things don't matter very much in everyday use, especially if you're used to an analogue scope and use the digital one as a sort of enhanced version of it. The 2430A, being an expensive unit when new, is relatively free of the strange vices and software bugs that can plague some modern scopes. While it has different limitations, it also has some features which are harder to find these days such as the peak detection and roll mode.

While not necessarily the best tool for analogue work (there lots of things on an analogue waveform it won't necessarily see as well as an analogue scope, for example a megahertz burst of instability on an audio-frequency sine wave) it should serve you well when you do want the digital features and measurements.

Chris

 

The main weakness of 2430/2430A is the CCD hybrids.
They came in, IIRC, 6 versions, 165-2074-00 thru 165-2074-05 and most of them aren't interchangeable.
Those are the large ones on the center of the mainboard. If you have -04 or -05 you are good.
Any lower prefix could be less reliable and may eventually fail.
If you take the cover off to examine do not power up the scope without forced cooling i.e. an external fan.
/HÃ¥kan

 

On Tue, 13 Feb 2018 07:02:45 -0800, you wrote:

Yesterday I snapped and bought a 2430A. I think I really need built-in measurements as they make life easier. The problem is I'm not sure if I made a good choice... 2430A I bought looks fully working with all originall manuals and even probes, very good condition. So I'm actually looking for a general opinion on the model - is it a good one?
Baring an idiosyncrasy because of how it works, there is nothing wrong
with the 2430A and related models. Their automatic measurement
capability works great.

I have a 2440 and always thought these CCD based DSOs were noisy
however after some comparisons with modern cheap DSOs and my 2230 and
2232 DSOs, I have concluded that they are comparable or better than
modern cheap DSOs as far as noise unless their CCD calibration needs
to be redone.

The idiosyncrasy is that being CCD based, they do not recover from
overload quickly but this is rarely a problem in most applications and
most other DSOs and analog oscilloscopes have the same problem even if
it is not as visible.

TomC
 

For an explanation of where that noise in digital scopes comes from see this video: https://www.youtube.com/watch?v=Znwp0pK8Tzk

On 2/13/2018 8:29 PM, David Hess wrote:
...
I have a 2440 and always thought these CCD based DSOs were noisy
however after some comparisons with modern cheap DSOs and my 2230 and
2232 DSOs, I have concluded that they are comparable or better than
modern cheap DSOs as far as noise unless their CCD calibration needs
to be redone.
...

Chuck Harris
 

It isn't so much that CCD's are noisy, as it is
that a 7 or 8 bit A-to-D converter only has 128
or 256 levels it can resolve. It pretty much has
to dither about one level, or another, which due
to the sparsity of levels, looks like noise. Gone
is the nice flat analog scope baseline trace when
the DSO is placed in the GND position.

Add another couple of bits to the A-to-D converter,
and your 2440 would look as smooth as silk.

-Chuck Harris

David Hess wrote:
On Tue, 13 Feb 2018 07:02:45 -0800, you wrote:
...
I have a 2440 and always thought these CCD based DSOs were noisy
however after some comparisons with modern cheap DSOs and my 2230 and
2232 DSOs, I have concluded that they are comparable or better than
modern cheap DSOs as far as noise unless their CCD calibration needs
to be redone.

The idiosyncrasy is that being CCD based, they do not recover from
overload quickly but this is rarely a problem in most applications and
most other DSOs and analog oscilloscopes have the same problem even if
it is not as visible.

 

We discussed Dave's video on the forum in the weeks after he posted it
and with all due respect to Dave, his analysis was incomplete. He
covered the display differences influencing the visual appearance of
noise but had the full capability there to make objective noise
measurements using the peak-to-peak and RMS measurement capability of
those DSOs and failed to do so. Had he done so, he would have found
that they actually do have higher noise if only because of the added
quantization noise and in many cases considerably higher noise than
even that can explain. The noise level of the 2225 he used is so low
that the minimum trace thickness itself conceals most of it so it
suffers from the same bias of looking noisier than it actually is.

The noise issue with the 24xx series of Tektronix DSOs is simply that
interleaving and the differential nature of the CCD based sampler have
the potential to add a lot of excess noise and will do so if the CCD
calibration is out of adjustment. Worn out power supply capacitors
also produce high noise before failing.

Here is an example of power supply noise in the 2440 which I returned.
I am sorry for the quality but it was one of the first digital camera
photographs that I took and it prompted me to get a better camera.

https://groups.io/g/TekScopes/photo/26835/0?p=Name,,,100,1,0,0

Under normal conditions the bad power supply really did look like just
added noise but I was able to trigger on it and use averaging to bring
out the power supply ripple which would not normally be evident on the
trace.

The "good" 2440 shown has about the same noise level at a 7A13
differential cascode amplifier which is about 10 times higher then a
single ended non-cascode vertical amplifier like a 7A18 or 7A26. That
difference is also about the same between a cheap and good modern DSO
so there is considerable variation in modern instruments for no good
reason.

On Tue, 13 Feb 2018 21:21:54 -0800, you wrote:

For an explanation of where that noise in digital scopes comes from see this
video: https://www.youtube.com/watch?v=Znwp0pK8Tzk

On 2/13/2018 8:29 PM, David Hess wrote:
...

I have a 2440 and always thought these CCD based DSOs were noisy
however after some comparisons with modern cheap DSOs and my 2230 and
2232 DSOs, I have concluded that they are comparable or better than
modern cheap DSOs as far as noise unless their CCD calibration needs
to be redone.
...

 

If we were talking about a 2230 or 2232 which have very low noise,
then I would accept that but the 24xx series DSOs I have seen have
considerably higher noise than the ADC quantization noise can explain
and especially so since their ADC has such a low sample rate and
bandwidth. But they still have lower noise than some modern DSOs so
it is not a matter of concern.

On Wed, 14 Feb 2018 00:48:16 -0500, you wrote:

It isn't so much that CCD's are noisy, as it is
that a 7 or 8 bit A-to-D converter only has 128
or 256 levels it can resolve. It pretty much has
to dither about one level, or another, which due
to the sparsity of levels, looks like noise. Gone
is the nice flat analog scope baseline trace when
the DSO is placed in the GND position.

Add another couple of bits to the A-to-D converter,
and your 2440 would look as smooth as silk.

-Chuck Harris

Chuck Harris
 

So, are you saying that the noise exhibited by the
2430/40 is greater than +/- 1/256 of the screen?

The last time I used one, I was disturbed by the
noise on the trace, but that noise looked to me to be
simply a large step quantization error that comes of
having an ADC with a 1mm step size.

I guess I will have to look at one again....Ah..no,
probably not.

-Chuck Harris


David Hess wrote:

If we were talking about a 2230 or 2232 which have very low noise,
then I would accept that but the 24xx series DSOs I have seen have
considerably higher noise than the ADC quantization noise can explain
and especially so since their ADC has such a low sample rate and
bandwidth. But they still have lower noise than some modern DSOs so
it is not a matter of concern.

On Wed, 14 Feb 2018 00:48:16 -0500, you wrote:

It isn't so much that CCD's are noisy, as it is
that a 7 or 8 bit A-to-D converter only has 128
or 256 levels it can resolve. It pretty much has
to dither about one level, or another, which due
to the sparsity of levels, looks like noise. Gone
is the nice flat analog scope baseline trace when
the DSO is placed in the GND position.

Add another couple of bits to the A-to-D converter,
and your 2440 would look as smooth as silk.

-Chuck Harris

Joe
 

Easy to use DSO loaded with desirable features, albeit with limited BW, but
you'll enjoy it for audio work. Given your 7603 and 465 in addition to the
2430A you can pretty much cover most of your needs unless you get into the
RF realm. For "quick and dirty" acquisitions the 2430A is my go to scope.

Joe

On Tue, Feb 13, 2018 at 9:02 AM, Marcin Marzeta <tek@...> wrote:

Dear Group,

My first post here. I'm in Poland and I design and build tube guitar amps.
I currently own a reliable 7603 and have recently started fixing my old
465 with DM44.

Yesterday I snapped and bought a 2430A. I think I really need built-in
measurements as they make life easier. The problem is I'm not sure if I
made a good choice... 2430A I bought looks fully working with all originall
manuals and even probes, very good condition. So I'm actually looking for a
general opinion on the model - is it a good one?

--
Marcin
marvelamps.com / 465 DM44 / 7603 / 2430A (on its way)



cmjones01
 

On Wed, Feb 14, 2018 at 04:21 am, Chuck Harris wrote:
The last time I used one, I was disturbed by the
noise on the trace, but that noise looked to me to be
simply a large step quantization error that comes of
having an ADC with a 1mm step size.

I guess I will have to look at one again....Ah..no,
probably not.
I've just switched on the 2430A on the bench behind me for the first time in a couple of months only to discover that the calibration backup battery has died (sigh, another job to do - the waveform backup battery died years ago) but it still comes up and runs. The noise on the trace looks exactly as I'd expect from a DSO: just +/- 1 bit, no more. Seems OK to me.

Chris

Chuck Harris
 

+/- 1 bit is how I remember it too... and a bit is about 1mm.

However, Dave Hess often looks at these things considerably
more analytically than I do. My experience with the 2430/40
was very casual... just long enough to know that since I can
have pretty much any DSO I want, I didn't want a 2440.

I figure that he has seen something that I probably didn't
pay any real attention to.

-Chuck Harris

cmjones01 wrote:

On Wed, Feb 14, 2018 at 04:21 am, Chuck Harris wrote:
The last time I used one, I was disturbed by the
noise on the trace, but that noise looked to me to be
simply a large step quantization error that comes of
having an ADC with a 1mm step size.

I guess I will have to look at one again....Ah..no,
probably not.
I've just switched on the 2430A on the bench behind me for the first time in a couple of months only to discover that the calibration backup battery has died (sigh, another job to do - the waveform backup battery died years ago) but it still comes up and runs. The noise on the trace looks exactly as I'd expect from a DSO: just +/- 1 bit, no more. Seems OK to me.

Chris

 

I like using my 2440 for one handed probing of digital circuits.

On Wed, 14 Feb 2018 06:35:16 -0600, you wrote:

Easy to use DSO loaded with desirable features, albeit with limited BW, but
you'll enjoy it for audio work. Given your 7603 and 465 in addition to the
2430A you can pretty much cover most of your needs unless you get into the
RF realm. For "quick and dirty" acquisitions the 2430A is my go to scope.

Joe

 

On Wed, 14 Feb 2018 06:10:23 -0800, you wrote:

On Wed, Feb 14, 2018 at 04:21 am, Chuck Harris wrote:
The last time I used one, I was disturbed by the
noise on the trace, but that noise looked to me to be
simply a large step quantization error that comes of
having an ADC with a 1mm step size.

I guess I will have to look at one again....Ah..no,
probably not.
I've just switched on the 2430A on the bench behind me for the first time in a couple of months only to discover that the calibration backup battery has died (sigh, another job to do - the waveform backup battery died years ago) but it still comes up and runs. The noise on the trace looks exactly as I'd expect from a DSO: just +/- 1 bit, no more. Seems OK to me.

Chris
The 2430A should be less noisy simply because it lacks the interleaved
CCD samplers used in the 2432A and 2440. If it is +/- 1 bit, then
that is very good.