Digital oscilloscope

[Mark Hennessy]

Cheap ones are the ones at about €100+ with only USB. Experienced them in work, 12 years ago., not 35 years ago. Total waste and they don't do X-Y properly.

I'd not call the Rigol DS1054Z cheap.

Well, it's a Vintage forum, mainly for hobby folk, so perhaps Mark was thinking of someone buying for work and I was thinking of the home enthusiast with little spare money.

I agree that cheap USB scopes are probably not a good buy. However, there's a lot of choice, and I don't have a lot of experience with many of them, so won't pretend to be an expert.

However, you'll note that Rigol was mentioned specifically in the original post. And if buying a cheap Rigol, that's a DS1054Z. It's been the "king" of cheap 'scopes for years, and while other manufacturers have had to respond, and might well produce 'scopes that are better for some people at that price point, the 1054Z still remains a really good pick. And I'm definitely talking hobbyist-level, not professional. Yes, we bought a dozen for work, but as mentioned, I've helped Rigol sell at least the same again to individuals. Though Dave Jones probably deserves the most commission

As I said, the specific points you raised were valid for early digital 'scopes. They might well be true (I honestly don't know) for a modern-ish USB 'scope, but you didn't state that you were talking about cheap USB 'scopes specifically - your wording was very general in nature, and you appeared to be tarring all digital 'scopes with the same brush. I've known you long enough to understand that is just how you write, and also appreciate that it is hard to change. But as I said, much as I usually ignore it, I do need to point it out now and again. I get PMs and emails about it; I know that some find your style off-putting. Please take that as constructive feedback - I'm not trying to upset anyone, I promise.

If you don't think the 1054Z is cheap, check out the price of similarly spec'd scopes from Tek and Keysight. Both have had to introduce low(er) cost 'scopes in response to Rigol and the others, but you're still paying a premium for the name and getting a lower specification overall. For some, that might be OK, of course - and many might be willing to pay for the reassurance of a top-tier brand. Horses for courses. I didn't mind paying £300 for my 1054Z, but if I was spending £1000 to £2000 on a 'scope, I probably would choose Keysight. I'd still keep the Rigol as it has an absolutely huge 24M-sample memory - that's 24 times what the Keysight 2000 X series can offer. That's because the sample memory is based on commodity DDR RAM on the Rigol, whereas Keysight have the sample memory within their custom ASIC. But while there's much less of it, it is considerably faster, meaning that the maximum capture rate is 200,000 waveforms per second, compared to 30,000 for the Rigol. Keysight naturally argue that theirs might capture details the Rigol would miss, and I know the reality isn't quite as simple as I'm making it sound, so the jury is out until I've had a chance to use one for a while. I'd expect the Keysight to have a better user interface that is a bit more responsive than the Rigol - that's the impression I've picked up from review videos. But even if it is much quicker to drive than the Rigol, I'd still keep my analogue 'scopes.

Restoring old radios or being a Radio Amateur hardly needs a scope at all.

I know this is a fairly widely held view, but I've always argued the opposite. Trying to work on radios without a 'scope is just masochistic! People in radio repair workshops 50 years ago managed with just an AVO8 because that's all they could afford, but would undoubtedly have solved the harder faults quicker if they'd had access to a 'scope. There is no reason to punish yourself today given the amount of cheaply available second-hand analogue 'scopes. As Rob says, today the problem is usually space rather than cash.

Fixing a radio without a 'scope almost certainly needs a higher level of understanding. Whereas a 'scope will really help a beginner to understand what's happening far more quickly. After a multimeter, a 'scope should be the next thing to acquire, and it should be used all the time, even it it's not absolutely essential. Without a 'scope, electronics is far more abstract. And it helps keep you warm in the winter

My view comes from working at a radio/TV shop 30 years ago. Just a Saturday job initially, but full time in the period between finishing A levels and leaving for university. The engineer there had a pristine 60MHz Hameg that was almost literally kept as a museum piece under a protective cloth. He only used it when he absolutely had to, and it was very frustrating to watch from my point of view - as a spotty 17 year old, I'd owned a 'scope for a year already, and could see him wasting time and sending himself mad because he didn't want to "wear it out"!

As I've said, and others concur, analogue 'scopes are best for this sort of work. But digital 'scopes can be invaluable in certain situations. Frank is certainly getting better value from his Rigol than I am, and I take my hat off to him; I haven't touched programmable logic in 25 years (ignoring a very basic intro session that I used to teach at work), and those were simple 22V10s IIRC. I do little bits of PIC still, but would have loved to have had the Rigol when creating the firmware for some of my bigger projects in the pre-children days. Analogue storage on my Telequipment DM63 was quite helpful, but the practically infinite zoom of the Rigol is just so addictive. But for analogue circuitry, it's hard to beat the immediacy of a traditional analogue 'scope with mechanical switches and potentiometers. Some analogue 'scopes had digital control interfaces, and those can be a bit hit-and-miss. For example, I didn't mind the Philips PM3055 and similar, but older colleagues hated them. It's obviously better if they remember their last state at power-up - not all did. Some digital interfaces rely on the CRT to display the values of variables like volts/div and timebase settings; better ones have secondary displays (like the PM3295 that I'm a big fan of). Philips made some great 'scopes, but constantly suffered from brand snobbery, which means they can be good buys today, and in my experience they are easier to repair than many of the models from the big names in 'scopes.

I'm waffling now. Sorry!

Mark