Oscilloscope advice

[spear]

Hi, I’m looking to purchase my first oscilloscope but overwhelmed by the amount features they have. I don’t want to waste money on features that I would not need or use, so need advice for a good unit that will fit my requirements. I will also want a signal generator.
It will only be used for audio stereo amplifier fault finding, able to display both channel sine waves simultaneously.
I’ve been looking at 2 channel 70mhz scopes but this is only based on my own limited knowledge on the subject. So would really appreciate your advice.
Budget is a bit limited at between £300 to £400 max.
Thanks

[Benta]

For your initial use, I'd go for an old-fashioned analog 'scope.
20 Mhz is plenty, and they're super easy to use.
Something like a Hameg HM203, you'll easily find a good one for 50 € on eBay.

Get used to working with it, then you can make an informed choice on what you need in the future.

[PGPG]

It will only be used for audio stereo amplifier fault finding, able to display both channel sine waves simultaneously.

Oscilloscope that is not enough good for observing up to 20kHz signals probably not exists.

[Wallace Gasiewicz]

I'm with Benta.     
Maybe get a little adventurous and go to a Hamfest with a good flea market.  Here in US old CRT scopes are going for almost nothing. You can plug the thing in and see if it works. Price should easily be well below 100 pounds.   And no shipping where they seem to break every CRT they can find.     
There are some that are not too old that are 10-20 MHz that would meet your needs.     
If you do not get any probes, I find that the cheap probes from China are pretty darn good.  Make sure you get the correct probes, the correct capacitance rating for the scope input.     

I find that for audio freq the old CRT Scopes are easier to use than the more modern Digital Scopes. I have both.   Might be a good place to start.     
Anyway just a suggestion, and my opinion,  hope not to get involved in CRT vs Digital scope discussion.

[tatel]

For your initial use, I'd go for an old-fashioned analog 'scope.
20 Mhz is plenty, and they're super easy to use.
Something like a Hameg HM203, you'll easily find a good one for 50 € on eBay.

Get used to working with it, then you can make an informed choice on what you need in the future.

+1

I think to find a good one for 50 € (on Ebay), you'll have to be very patient. Last week I got one for about 80 €, shipped, which seems to be good but it's still on the way, so I still don't know. Ebay prices get easily over 100 €

But, being on the UK, it will probably be easier to you. Getting one at a Hamfest would be the easiest way to get it for cheap, as Wallace said.

[tggzzz]

Hi, I’m looking to purchase my first oscilloscope but overwhelmed by the amount features they have. I don’t want to waste money on features that I would not need or use, so need advice for a good unit that will fit my requirements. I will also want a signal generator.
It will only be used for audio stereo amplifier fault finding, able to display both channel sine waves simultaneously.
I’ve been looking at 2 channel 70mhz scopes but this is only based on my own limited knowledge on the subject. So would really appreciate your advice.
Budget is a bit limited at between £300 to £400 max.
Thanks

It will partly depend on what interpretation you will need to place on the displayed traces.

If you are intending to look at harmonic distortion, then you would need a digitising scope with a 12 bit (or higher) digitiser. A spectrum analyser might be a better choice.

If you are looking at PSU noise and ripple, anything will be sufficient.

If you are looking at the shape of an analogue waveform, e.g. to spot faulty components, tweak biassing or to spot when slew rate limitation causes TID, then anything will be sufficient.

If you are looking at the noise levels, then you need a scope with particularly low noise. That requires low bandwidth, as low as possible.

As others have said, a working analogue scope sounds like an ideal starting point. The rule of thumb is £1/MHz for something dubious (a little more for something you can see workin), and you don't need many MHz!

For any scope, if you are particularly interested in valve equipment, then you will need to ensure the high voltages don't damage the scope or you, and to be sure whether or not the the chassis is connected to mains earth (the probe shield must be connected to mains earth, for your safety).

[Mahagam]

However, modern digital scopes have one big advantage – they can automatically plot the frequency response of an amplifier.

[tggzzz]

However, modern digital scopes have one big advantage – they can automatically plot the frequency response of an amplifier.

There are limits to that. We have no idea what the OP wants and needs in that respect.

[spear]

Thanks for your  replies. I have already read elsewhere that the analogue scopes are easier to use, however, due to limited space (in my shed) I just have enough space for a small shelf over the worktop that would accommodate a digital scope.

[Aldo22]

Thanks for your  replies. I have already read elsewhere that the analogue scopes are easier to use, however, due to limited space (in my shed) I just have enough space for a small shelf over the worktop that would accommodate a digital scope.

If you would answer tggzzz's questions, you could get more specific help (harmonic distortion, noise levels, high voltage).

[NE666]

I just have enough space for a small shelf over the worktop that would accommodate a digital scope.

Indeed. You really don't need some 20+ year old analog door stop of unknown provenance and condition, most of which are (imho) still at silly asking prices for what they are in today's scope market.

For the budget you've indicated, and given that you're in the UK, I suggest that you have a look at what Telonic.co.uk can supply. (NOTE; I'm not affiliated or connected with them in any way, nor do I gain anything from recommending them. It's just that I've used them in the past and been pleased with their pricing and customer service).

Rigol DS1102Z-E        243 GBP inc. VAT
Rigol DHO802            345 GBP inc. VAT
Siglent SDS802X-HD  374 GBP inc. VAT

All perfectly fine for basic waveform visualisation and measurements. Yes, they are digital but you only benefit from that. They are really no harder to learn to use for the beginner, especially with some of the excellent resources available on the t'interweb.  I'd liken it to learning to drive a modern 8-speed automatic car with 4wd and adaptive cruise-control etc., rather than your grandfather's first car.  The latter might seem to have some simplicity appeal, until you've a few miles under your belt and realise that the latter isn't near so friendly or comfortable on long journeys or driving in stop-start traffic in town as you thought it would be.

If this is your first scope and you need to embark on a learning curve, I would recommend investing your time and efforts in the contemporary rather than a history lesson.

As others have said though, if you have specific requirements e.g. noise measurements, they need to be taken into account during this specifying phase.

[PGPG]

due to limited space (in my shed)

You can also consider USB driven (without own screen) scopes.

In my opinion in use they are generally worse than standard scopes but...
We have recently bought one only because you can use it with laptop working from its battery. It allows to avoid GND loop when measuring something in AC supplied device.

[tggzzz]

Indeed. You really don't need some 20+ year old analog door stop of unknown provenance and condition, most of which are (imho) still at silly asking prices for what they are in today's scope market.
...
For the budget you've indicated,
...
If this is your first scope and you need to embark on a learning curve, I would recommend investing your time and efforts in the contemporary rather than a history lesson.
...
As others have said though, if you have specific requirements e.g. noise measurements, they need to be taken into account during this specifying phase.

The OP will pay, one way or another, to gain experience.

The advantages of a working old scope are that

• it would be cheap enough that it could be thrown away if that turns out to be beneficial. The "sunk cost" wouldn't be an impediment.
• the OP would have gained knowledge so that they could get what they need, rather than what they currently think they need
• low-end (new) scopes have subtle disadvantages that a beginner is unlikely to be in a position to understand. Whether the disadvantages would matter to the OP is a separate question, of course
• the OP could spend their limited budget on other equipment, potentially expanding their opportunities/capabilities

The one USP of a digitising scope is to capture one-off events. In audio applications, PSU startup/shutdown problems spring to mind.

Old analogue scopes might be too large/heavy for the OP, but many are light and might fit in the available space.

Personally I wouldn't like a scope to be on a shelf, since that would give me a crick in the neck, and I couldn't swivel my eyeballs between the trace and whatever I'm touching with the probe.

[NE666]

The one USP of a digitising scope is to capture one-off events. In audio applications, PSU startup/shutdown problems spring to mind.

That, and recurring but infrequent events of course.

A factor that I am considering is that if the OP has limited or no experience with scope use, when it comes to buying used equipment of ages past, how are they to be certain that it operates correctly in the first place? The value in paying extra for something factory fresh is that is in a known good state upon receipt. Anything 'odd' or unexpected is then clearly attributable to learning disconnect / misuse, rather than 'should it be doing this??'

I also think that 50 to 100 GBP isn't such a small sighting investment, when the price of a (potentially) suitable new unit could be 'just' 250. If the OP later finds that this isn't for them, there will be some easily recoverable resale value in the latter, which is questionable in the case of the former.

 

[tggzzz]

The one USP of a digitising scope is to capture one-off events. In audio applications, PSU startup/shutdown problems spring to mind.

That, and recurring but infrequent events of course.

A factor that I am considering is that if the OP has limited or no experience with scope use, when it comes to buying used equipment of ages past, how are they to be certain that it operates correctly in the first place? The value in paying extra for something factory fresh is that is in a known good state upon receipt. Anything 'odd' or unexpected is then clearly attributable to learning disconnect / misuse, rather than 'should it be doing this??'

I also think that 50 to 100 GBP isn't such a small sighting investment, when the price of a (potentially) suitable new unit could be 'just' 250. If the OP later finds that this isn't for them, there will be some easily recoverable resale value in the latter, which is questionable in the case of the former.

Fair points - except £50-100 would be an unnecessarily high price. £10-20 is more reasonable.

Depending on the measurements the OP wants to make, £250 is probably too low for a new scope. For example, how much are cheap 14bit scopes?

One serious possibility would be the Digilent Analog Discovery, since it includes a 14bit AWG.

[tunk]

I think this is the cheapest 2ch digital scope:
https://www.eevblog.com/forum/testgear/new-$40-2ch-pocket-scope-2mhz50msps-(august-2023)/
When/if the OP finds he needs more, then he can get something better.

[tatel]

For any scope, if you are particularly interested in valve equipment, then you will need to ensure the high voltages don't damage the scope or you, and to be sure whether or not the the chassis is connected to mains earth (the probe shield must be connected to mains earth, for your safety).

^^^^
This. Better to learn with a cheap, well-built, old analog oscilloscope, I think. I for sure know I don't want to do that kind of work (HV) with my  €500 entry-level benchtop oscilloscope.

[Xena E]

.. due to limited space (in my shed) ...

Taking that comment literally:

Beware of damp! Particularly with crt scopes, it's a killer...

[Gyro]

due to limited space (in my shed)

You can also consider USB driven (without own screen) scopes.

In my opinion in use they are generally worse than standard scopes but...
We have recently bought one only because you can use it with laptop working from its battery. It allows to avoid GND loop when measuring something in AC supplied device.

Indeed, a USB scope might be an acceptable solution in this case. the Picoscope 2205A is currently £185 (UK), has 2 x 25MHz bandwidth channels (200 Ms/s total) and an MSO included. Although I don't find the UI that intuitive (although the OP might, it resembles a standard PC app more), it does include all the software features of the Picoscope S/W. This includes things like FFT display and direct distortion measurements (I don't know about frequency response plots), although measurement range is going to be rather limited by being an 8 bit scope.

For around £90 the Owon VDS1022I is another option with the same bandwidth. This has galvanic isolation at the USB port so offers protection of the laptop, prevents ground loops and reduces noise without the need to unplug. It has no MSO or distortion measurements though other than FFT display. Again an 8 bit scope.

The word "shed' worries me a little. Sheds can be anything from well heated and insulated dry environments to damp and cold affairs. Damp and cold storage are the worst enemies of traditional, gracefully aging, analogue scopes with all of their switch contacts and tantalum bead capacitors. [Edit: as Xena E says]

On the general subject of size, a modern DSO is way shallower than a CRT analogue scope, and lighter too,but the front panel dimensions of my DS1102Z-E are almost exactly the same as my old Tek 475A analogue. Size can mean different things in different situations.

[tggzzz]

.. due to limited space (in my shed) ...

Taking that comment literally:

Beware of damp! Particularly with crt scopes, it's a killer...

Why "particularly with crt scopes"?

N.B. Tek used to recommend cleaning their scopes' interior with detergent and water in a "wash booth". See https://w140.com/tekwiki/images/6/63/Tekscope_1976_V8_N4_with_Supplement.pdf p13ff. No, I wouldn't do it either, but it does indicate why your comment may not be correct.

[Gyro]

Why "particularly with crt scopes"?

N.B. Tek used to recommend cleaning their scopes' interior with detergent and water in a "wash booth". See https://w140.com/tekwiki/images/6/63/Tekscope_1976_V8_N4_with_Supplement.pdf p13ff. No, I wouldn't do it either, but it does indicate why your comment may not be correct.

The speed of the detergent wash and the 24 hours in a drying oven would seem to be an obvious difference from cold damp storage. I would expect damage to a DSO too, especially things like the encoders and maybe tactile button PCB pads.

That cleaning procedure does look brutal though - Furniture polish and WD40 on the switches and pots? Ajax for the front panel! 


EDIT: As far as why CRT scopes, EHT and cathode bias voltage supplies come to mind.

[tggzzz]

Why "particularly with crt scopes"?

N.B. Tek used to recommend cleaning their scopes' interior with detergent and water in a "wash booth". See https://w140.com/tekwiki/images/6/63/Tekscope_1976_V8_N4_with_Supplement.pdf p13ff. No, I wouldn't do it either, but it does indicate why your comment may not be correct.

The speed of the detergent wash and the 24 hours in a drying oven would seem to be an obvious difference from cold damp storage. I would expect damage to a DSO too, especially things like the encoders and maybe tactile button PCB pads.

That cleaning procedure does look brutal though - Furniture polish and WD40 on the switches and pots? Ajax for the front panel! 


EDIT: As far as why CRT scopes, EHT and cathode bias voltage supplies come to mind.

The past is a foreign country, they do things differently there

Completely unconvinced that the 2450V is relevant, provided it isn't damp when switched on. My Tek485 (which I bought on a whim while collecting a 465 CRT) had been stored in something not far away from a  farm shed, worked just fine apart from some unsubtle and some subtle electrolytic cap problems. The 465 CRT had been stored similarly.

OTOH I have, of course, found damp damaged equipment - but without CRTs/kV.

Hence I still think Xena E's comment needs justification.

[spear]

due to limited space (in my shed)

You can also consider USB driven (without own screen) scopes.

Thanks for the suggestion but have already considered the USB option and ruled it out as I would not have the space for the laptop.

[spear]

I just have enough space for a small shelf over the worktop that would accommodate a digital scope.

Indeed. You really don't need some 20+ year old analog door stop of unknown provenance and condition, most of which are (imho) still at silly asking prices for what they are in today's scope market.

For the budget you've indicated, and given that you're in the UK, I suggest that you have a look at what Telonic.co.uk can supply. (NOTE; I'm not affiliated or connected with them in any way, nor do I gain anything from recommending them. It's just that I've used them in the past and been pleased with their pricing and customer service).

Rigol DS1102Z-E        243 GBP inc. VAT
Rigol DHO802            345 GBP inc. VAT
Siglent SDS802X-HD  374 GBP inc. VAT

Thanks for the info, will have a look at these

[spear]

Hi, I’m looking to purchase my first oscilloscope but overwhelmed by the amount features they have. I don’t want to waste money on features that I would not need or use, so need advice for a good unit that will fit my requirements. I will also want a signal generator.
It will only be used for audio stereo amplifier fault finding, able to display both channel sine waves simultaneously.
I’ve been looking at 2 channel 70mhz scopes but this is only based on my own limited knowledge on the subject. So would really appreciate your advice.
Budget is a bit limited at between £300 to £400 max.
Thanks

It will partly depend on what interpretation you will need to place on the displayed traces.

If you are intending to look at harmonic distortion, then you would need a digitising scope with a 12 bit (or higher) digitiser. A spectrum analyser might be a better choice.
For any scope, if you are particularly interested in valve equipment, then you will need to ensure the high voltages don't damage the scope or you, and to be sure whether or not the the chassis is connected to mains earth (the probe shield must be connected to mains earth, for your safety).

Well this is the problem, as a beginner with scopes, initially I'd be looking for basic fault finding but who knows, as I progress over time I may well need the more advanced  features that you have outlined. With this in mind,  I would be looking for a scope that has the capacity to accommodate me as required, assuming it's within my budget.