My first oscilloscope

[miguelvp]

One more thing, DSOs are analog scopes on the front end, because there is no other way around it.

Front ends now are much better than back then, the sampling is way higher than old DSOs and the menus are intuitive, at least they are for me.

But because analog only scopes do hide information, they are cool to use for vector graphics based on sound. Digital ones can't really hide well the low level traces connecting what is intended to be viewable.

[GK]

My old Philips analogue scope is way easier to service than any crappy fancy schmancy DSO. Still going ~70 years on! Ha! End of discussion.

[tautech]

My old Philips analogue scope is way easier to service than any crappy fancy schmancy DSO. Still going ~70 years on! Ha! End of discussion.

   
Not really.

BW?

But really nice ol' Tek Glen. 

[G0HZU]

Newsflash: Mixed Domain is *not* FFT. Most of the early day DSOs (the ones from 20 years ago you usually take as examples to explain why DSOs suck!) didn't have FFT or only as an option, but for the last 15 years or so FFT has been pretty much a standard feature of DSOs.

Mixed-Domain refers actually refers to digital inputs (i.e. logic analyzer) which a MSO offers in addition to its analog inputs.

I'm not really that interested or clued up about the modern scope related marketing terms but I thought that 'mixed domain' was a Tektronix marketing term for a range of their scopes that offered both time and frequency domain measurements to be made together.

i.e. a mixed signal scope (MSO with analogue and digital inputs) combined with an FFT based spectrum analyser = MDO.

[miguelvp]

My old Philips analogue scope is way easier to service than any crappy fancy schmancy DSO. Still going ~70 years on! Ha! End of discussion.

For servicing, Nothing beats a Tek 5110 with 5A24N modules (2 MHz)









Well, nothing other than a string and some cans

[Howardlong]

Newsflash: Mixed Domain is *not* FFT. Most of the early day DSOs (the ones from 20 years ago you usually take as examples to explain why DSOs suck!) didn't have FFT or only as an option, but for the last 15 years or so FFT has been pretty much a standard feature of DSOs.

Mixed-Domain refers actually refers to digital inputs (i.e. logic analyzer) which a MSO offers in addition to its analog inputs.

I'm not really that interested or clued up about the modern scope related marketing terms but I thought that 'mixed domain' was a Tektronix marketing term for a range of their scopes that offered both time and frequency domain measurements to be made together.

i.e. a mixed signal scope (MSO with analogue and digital inputs) combined with an FFT based spectrum analyser = MDO.

That is my understanding also. Mixed domain, as in measurement in both time and frequency domains, much as we say an regular oscilloscope is a time domain instrument and a spectrum analyser is a frequency domain instrument.

[mzzj]

If you understood how to repair that This Tektronix 465, you might actually know something about electronics.

One may understand how to fix POS  Tek 465 and another understand how to fix it and why its not worth of fixing 

[Wuerstchenhund]

I'm not really that interested or clued up about the modern scope related marketing terms but I thought that 'mixed domain' was a Tektronix marketing term for a range of their scopes that offered both time and frequency domain measurements to be made together.

i.e. a mixed signal scope (MSO with analogue and digital inputs) combined with an FFT based spectrum analyser = MDO.

You're right, my bad. MDO is indeed a marketing term coined by Tektronix for their scope which have an integrated Vector Spectrum Analyzer (which isn't quite the same as the FFT functionality in most scopes).

FFT on the other side has been pretty standard in most DSOs at least since 2000.

[Wuerstchenhund]

If you understood how to repair that This Tektronix 465, you might actually know something about electronics.

One may understand how to fix POS  Tek 465 and another understand how to fix it and why its not worth of fixing 

  How true. Not everything that can be fixed is actually worth fixing.

[G0HZU]

That is my understanding also. Mixed domain, as in measurement in both time and frequency domains, much as we say an regular oscilloscope is a time domain instrument and a spectrum analyser is a frequency domain instrument.

Yup.

One party trick the old Tek 465 can do is to connect the rear panel 'CH1 vertical out' to the RF input of a conventional spectrum or signal analyser (with a limiter inline for safety)

This way you can use the 465 to probe with a scope probe in the time domain and also look at the frequency domain with the analyser. The analyser could be configured to show the frequency (or time) domain and also to demodulate the signal. All from the same scope probe. The 465 effectively becomes a variable gain RF probe with a time domain display (scope) built in

You can do similar with a modern DSO by displaying an FFT but it isn't going to deliver the same performance as a decent spectrum/signal analyser if you are looking for very small signals near very large ones.

[Wuerstchenhund]

One party trick the old Tek 465 can do is to connect the rear panel 'CH1 vertical out' to the RF input of a conventional spectrum or signal analyser (with a limiter inline for safety)

This way you can use the 465 to probe with a scope probe in the time domain and also look at the frequency domain with the analyser. The analyser could be configured to show the frequency (or time) domain and also to demodulate the signal. All from the same scope probe. The 465 effectively becomes a variable gain RF probe with a time domain display (scope) built in

You can do similar with a modern DSO by displaying an FFT but it isn't going to deliver the same performance as a decent spectrum/signal analyser if you are looking for very small signals near very large ones.

It's been a long time since I touched a Tek 465 but if my memory serves me right the Ch1 Vert out on the rear didn't provide the signal at the Ch1 input at the front but the resulting vertical signal after the preamp and attenuator stages, and therefore was limited to the dynamic range of the scope's internal amplifiers. I very much doubt that the resulting dynamic range was any better than what you can see on a DSO using FFT, especially when considering that the Tek 465 didn't had the most sensitive input section anyways.

[paulie]

I don't want to spend a lot of money because my budget is very limited.
I want to use the oscilloscope to measure the ripple at the output of a linear power supply.

As usual forum noisemakers totally ignore content of the oiginal post. Most probably don't even bother to the read even the previous post before shooting off. Then they ask "Where did OP go? How rude!". LOL

And did I ever mention very free with other peoples money? In this case not a single answer so far to the question "Can you get a DSO for under $100". Well, it's "No", unlike hundreds of analog deals ranging $20-$50.

Ignoring all the apples/oranges he says she says, bottom line is DSO lets you peek past and future whereas analog is for NOW!! All the other garbage is pretty much blah blah blah for most hobby use. Of course the 0.01% hobby snobs posing from in front of their wall of over-priced gear will disagree.

[G0HZU]

As usual forum noisemakers totally ignore content of the oiginal post.

I hope that wasn't aimed at me? 

The old Tek 465 can be bought for peanuts these days if you are patient. I paid about £50 for mine way back in the 1990s.

I still use it today and a 465 is definitely worth considering as a cheap first scope if the budget is low.

It can still be useful even to a professional and I gave an example trick it can do. The OP could do the same with a soundcard to replace the RF spectrum analyser at the rear CH1 vertical.

So, if we consider the original requirement of the OP you can probe a PSU for ripple in mixed domain using a 465 and any old PC from the last 15 years that has a soundcard and is running a basic (freeware) spectrum analyser program. Just connect the PC soundcard to the rear Ch1 vertical input of the 465 and you have a low frequency spectrum analyser for free as you probe with the scope and a x10 probe or a direct screened/shielded connection or a differential probe. You could also capture the ripple with the soundcard as a wav file and postprocess it and look at it in the time domain or frequency domain.

[Wuerstchenhund]

As usual forum noisemakers totally ignore content of the oiginal post.

 

Had you actually read the thread, instead of just ranting ahead, then you might have noticed that the OP's question has been answered within the first number of replies (and many people recommended to save just a bit more and get a DS1054z instead of getting an old analog scope now). This way You also would have noticed that there where some questions for the OP to clarify, too, to which he never replied, but yeah, I understand that I'm probably expecting a bit too much there.

[paulie]

Funny you should mention soundcard. For the purpose of this thread there are dozens of software based scopes available for free download. You can't get much cheaper than that. And even considering hardware stand-alone DSO I should take back about not getting for under $100. Those DSO201 ARM based "pocket scopes" can be had for about half that:

http://www.ebay.com/itm/Portable-Mini-Nano-ARM-DSO201-Pocket-sized-Handheld-Digital-Storage-Oscilloscope-/251801605488?pt=LH_DefaultDomain_0&hash=item3aa08b9570

Certainly adequate for what mike-mike needs and for that matter the even cheaper (~$30) AVR based dealies would suffice.

[tautech]

And while we are looking at cheap measurement options for the OP, if he has a reasonable DMM, it should give him a good idea of ripple on a PSU if the ripple is within the frequency range of his DMM.
AC mV. 

[paulie]

True, DMM will be quite useful for judging how much ripple. Unfortunately in many cases, as hinted in a recent electronics thread, the waveform can be even more important. Specially for a switcher and you want to determine if it's working properly and best way to fix if not. Or if it is working but noisy and you need to filter.

[G0HZU]

It's been a long time since I touched a Tek 465 but if my memory serves me right the Ch1 Vert out on the rear didn't provide the signal at the Ch1 input at the front but the resulting vertical signal after the preamp and attenuator stages, and therefore was limited to the dynamic range of the scope's internal amplifiers. I very much doubt that the resulting dynamic range was any better than what you can see on a DSO using FFT, especially when considering that the Tek 465 didn't had the most sensitive input section anyways.

I think it's front end sensitivity is quite good. Maybe you can give me some figures for what noise figure you think it has across most of the 100MHz input bandwidth?

When coupled to a spectrum analyser it can also easily display two test tones and show about -75dBc 3rd order IMD levels (for a signal waveform that fills the CRT) and this is probably 15dB better than many 8 bit DSOs can manage in FFT mode.

Then there is the issue about annoying alias terms in the DSO FFT that won't be there in a conventional spectrum analyser connected to a 465. So far fewer annoying phantom alias terms to worry about.

I usually use an active RF probe straight into the analyser for stuff like this but not everyone has a decent RF probe. The Tek 465 can act as a very robust RF probe with variable gain via the front panel Y controls and this can feed a hobby spectrum analyser or a counter or a receiver. Its front end can provide some signal gain as well and I can easily look at signals of <<0.5uV amplitude this way (i.e. arriving at the 465 CH1 and then displayed on the analyser via the CH1 rear output) .

Note: it's best to fit a DC block and a limiter inline between the 465 and the analyser if the analyser doesn't have an internal DC block and also has a lowish damage level.

It's a cheap and effective option

[Rupunzell]

How does a gaussian response system (real time)  from input connector to CRT phosphor hide noise?

Down load the service manual and do the performance checks. Before that omit the probes going direct from a calibrated level test generator direct to the inputs.


Bernice

I do prefer the DSO since it can show the noise the 7613 with the 7A13 hides.

Edit: BTW that is a 40mVpp signal using an x10 probe, so it should show 4 divisions like the Rigol instead of 2. Weird.
Edit2: Also the 1KHz test signal using the 40mVpp signal is not really 1KHz.

[Rupunzell]

Here is what the 7A13 should look like at the 1mV/Div at 100Mhz and 5Mhz with a FG input. The un-used input must be set to ground or terminated or set to internal Vc or to the same impedance as the used input or the displayed amplitude could be what you're observing will be wrong. This is a basic rule of using diff input amplifiers.

Text book measurements like these are of extremely limited information and telling of what the 7A13 can do in real world test set up requirements. These basic measurements are what the modern DSO's do so very well at complete with a on display box full of data. No user interoperation needed. This is the great appeal for the vast majority of time domain instrument users. These are the types of measurements that have the lowest meaningful data and usefulness for the stuff I do.

7A13, 1Khz sine, 1mV/Div, 100 Mhz, single ended input:


7A13, 1Khz tri, 1mV/Div, 100 Mhz, single ended input:
*Notice the over shoot spike at the peak of the triangle wave.


7A13, 1Khz tri, 1mV/Div, 100 Mhz, single ended input:


7A13, 1Khz sine, 1mV/Div, 5 Mhz, single ended input:


7A13, 1Khz tri, 1mV/Div, 5 Mhz, single ended input:


7A13, 1Khz step, 1mV/Div, 5 Mhz, single ended input:



For comparison, Tek 7A22.
The noise spectra can be determined by usual observation in real time, in these time exposure images that data is mostly lost as the exposure time integrates the noise camera exposure time. The peak noise and much more visual information is not visible in these images. A video would illustrate this better than still images.

7A22, 1Khz sine, 10uV/Div, 1 Mhz, single ended input:


7A22, 1Khz Tri, 10uV/Div, 1 Mhz, single ended input:


7A22, 1Khz step, 10uV/Div, 1 Mhz, single ended input:


7A22, 1Khz sine, 10uV/Div, 100 Khz, single ended input:


7A22, 1Khz tri, 10uV/Div, 100 Khz, single ended input:


7A22, 1Khz step, 10uV/Div, 100 Khz, single ended input:


*Some one with a modern new "fancy dancy" DSO need show-prove this exact measurement at 10uV/Div, 1Mhz BW and 100Khz BW at the DSO's input. NO ADD ON, Pre-amps or external aids.



These inverted contact Tektronix relays were used in a LOT of tek instruments. They have very good BW and very low coupling from the coil to contacts. Over time like most all mechanical devices, they can wear out. Do wiggle them in their sockets as the sockets are know to become intermittent if the instrument is not used. Replacements can be the original Tek part or Teledyne T0-5 relays. Send me a PM if you need help with these.

Bernice

Much better now (with ground spring), although it keeps on jumping to two division, but changing the Volts/div to 2 mV and back to 1 mV get's it back.

I just hope is not the miniature relays that is causing the volts/div to half every now and then or I'll have to deal with this:
(with google translate from German to English)

But it seems the 7A11 I got, also has the same relays.

[Rupunzell]

Yes, the vertical amplifier sections can be cascaded to increase sensitivity. The objective of this is NOT to increase dynamic range, it is done to increase input sensitivity at the trade off of lower BW. The input might not be that "sensitive" but the inputs are low noise and low noise makes all the difference.

Bernice

It's been a long time since I touched a Tek 465 but if my memory serves me right the Ch1 Vert out on the rear didn't provide the signal at the Ch1 input at the front but the resulting vertical signal after the preamp and attenuator stages, and therefore was limited to the dynamic range of the scope's internal amplifiers. I very much doubt that the resulting dynamic range was any better than what you can see on a DSO using FFT, especially when considering that the Tek 465 didn't had the most sensitive input section anyways.

[Rupunzell]

Guess we are gong to have another roll. Try replicating the LM317 & LM337 noise current and internal band gap switching measurement posted else using your fav DSO. The image results are going to look like this, The prime trace of interest in the one in the center which is 10mA/Div. The peak current off screen is >100mA, current noise on that trace ranges from less than 1mA to just over 10mA.






And.. I'm waiting for YOU to post an image of your fave DSO at 10uV/Div with a 20uV peak to peak signal.

Stop typing for a moment and show us your test and measurement skills and understanding of what is happening and why.

Bernice

DSOs actually fit both, digital design as well as analog design much better than analog scopes.

Yes, analog scopes have their place, which in these days is a museum. I appreciate that this is difficult for you to understand (since your awareness of DSOs seems to be limited to what was available >15 years ago) but in 2015 there is really no reason why one should choose an analog scope over a DSO.


EDIT: mixed up MSO and MDO - corrected.

[Rupunzell]

Once an individual becomes closed minded and learning resistant, the possibility of knowledge gained is lost and the malignancy or ignorance, prejudice and discrimination within that individual simply grows.

It is so very easy to criticize what one does not understand and discount the knowledge and expertise offered. If the scientific community had this attitude and ideology, the very foundation of science and technology would mostly fall apart.

These statements also says much about those who wrote them.


Bernice

If you understood how to repair that This Tektronix 465, you might actually know something about electronics.

One may understand how to fix POS  Tek 465 and another understand how to fix it and why its not worth of fixing 

  How true. Not everything that can be fixed is actually worth fixing.

[tggzzz]

Once an individual becomes closed minded and learning resistant, the possibility of knowledge gained is lost and the malignancy or ignorance, prejudice and discrimination within that individual simply grows.

It is so very easy to criticize what one does not understand and discount the knowledge and expertise offered. If the scientific community had this attitude and ideology, the very foundation of science and technology would mostly fall apart.

These statements also says much about those who wrote them.

If you understood how to repair that This Tektronix 465, you might actually know something about electronics.

One may understand how to fix POS  Tek 465 and another understand how to fix it and why its not worth of fixing 

  How true. Not everything that can be fixed is actually worth fixing.

True, unfortunately.

[mzzj]

Here is what the 7A13 should look like at the 1mV/Div at 100Mhz and 5Mhz with a FG input. The un-used input must be set to ground or terminated or set to internal Vc or to the same impedance as the used input or the displayed amplitude could be what you're observing will be wrong. This is a basic rule of using diff input amplifiers.
.
.
.
.

SOME of the old analog scopes definitely have nice to have features but how many analog scopes out there you can find with 10uV/div sensitivity?
This side of the pond ie.  tek 7000 is nearly impossible to find, I have yet to see mainframe scope in their natural habitat.  Your situation in US might be better.
Back then I had to use external preamp with my analog tek 475 and still have to use external preamp with my current DSO.