Recommendations for a cheap 'scope

[David G4EBT]

I've had a Hameg 203-7 analogue scope for some years now, which I've found excellent and more than sufficient for hobbyist needs. In its day, it was the largest selling 'scope across Europe, and found its way into schools, universities and labs. It's solid state, dual trace, and though nominally its upper limit is stated as 20 MHz, as will be seen from the first pic below, (a 30MHz sine wave), it's happy at 30MHz.

It has a built in square-wave calibrator at 0.2V and 2V, and as a bonus, also has a built-in component tester. Because they sold in such large numbers, they often come up in good condition on e-bay, though personally, I'd only buy a 'scope off e-bay if I could collect it in person, due to the high risk of damage in transit. Typical prices are £60 - £80.

First pic is 30mHz sine wave, second pic shows upper and lower traces displaying 1V/Div from the 2V internal calibrator, third pic is a 1N4148 silicon diode connected to the component tester, fourth pic is a germanium diode and the last pic is a 7V5 zener diode. (The traces to expect from a good component are shown in the manual).

There's an excellent paper at the Eddystone User Group by Gerry O'Hara - a Canadian radio amateur - entitled 'Technical Shorts - Oscilloscopes in Radio Servicing at this link:

http://eddystoneusergroup.org.uk/Res...0Servicing.pdf

As luck would have it, that paper features a Hameg scope and explains all the settings, though much of what's said is common to other 'scopes.

I'd echo the sentiments of others in this thread, that I make little use of my 'scope in radio servicing, but I do use it quite a lot for homebrew electronic projects. For radio restoration and fault diagnosis, in order of usefulness after digital and analogue multi-meters, I'd say signal injector/tracer, Chinese multi-tester, signal generator. I can't think when I last used my 'scope on a radio.

I just ordered one of those eBay kits, purely for interest's sake.

So have I, does this forum have a stake in ebay silly items I wonder? Well Julie, a competition to who gets the first waveform on screen and how useful it is, could be of use to the OP. Ordered the kit, it costs a whopping 7p more for the assembled version.

[Nickthedentist]

I totally agree with David about these Hamegs.

They sometimes turn up cheaper on here, so keep your eyes peeled.

N.

[MrBungle]

The component testers on those Hameg scopes are worth their weight in gold.

[Radio Wrangler]

I picked up one of the little Hamegs at a radio club junk sale. It made a nice extra christmas present for my brother.

Good little scopes.

David

[mhennessy]

Originally Posted by Bonky28

Do I gather that something like this: http://www.ebay.co.uk/itm/DSO138-2-4...687MGNdY1VPq4A

A note about these kits: they are widely cloned and fakes are everywhere. I have one, but bought it from Banggood, as they are a distributor.

I've also picked up a DSO150, which promises to be better, but haven't got around to building it yet. They are frequently on special offer - mine was only a tenner.

Of my selection of 'scopes here, my ancient Telequipment DM63 is the one I use most. I have a Rigol DS1054Z, and it's amazing for certain tasks that are impossible on an analogue 'scope, but I've never used it for fixing radios. I also have a high bandwidth Philips 'scope, but again that only gets used for those occasions when the 20MHz of the DM63 isn't enough. Going beyond a few 10s of MHz requires specialist knowledge about probing and loading effects - so as a beginner, I'd echo the excellent advice to pick up a simple 20MHz unit.

I'm firmly in the "like to see it" camp. I believe that oscilloscopes help to speed up the process of learning how electronics works - it might take a bit of time and patience to learn how to use a 'scope, but like any powerful tool, time spent getting acquainted with it is time well spent.

[Argus25]

There seems to be a general feeling in this thread that analog scopes will be unreliable and need fixing.

I can report:

That the 3 Hitachi V509's remain fault free from new, I think they were made in the early 1980's. One reason why I suggested this scope to the OP.

The Tek scopes, 3 2465B's and 3 464's I have, have all required repairs. The 2465B's due to leaked surface mount electrolytics and failed NVram batteries. The 464's due to power supply electros, attenutor switch issues and intermittent pcb presets .

A Sony-Tek scope, 80's vintage, no repairs, so it seems the Japanese have the magic touch with reliability.

The worst scope for faults, but it is older, is my Telequipment D52. EHT rectifier & filter capacitor failures, open circuit resistors, multiple repairs required.

So perhaps a good rule of thumb; analog scopes older than 1980 probably will need repairs, especially Telequipment.

[Ted Kendall]

Another vote for Hameg. I bought a 205-3 new .... years ago, and it works as well as it ever did. Lovely tool.

[Argus25]

Originally Posted by David G4EBT

I'd echo the sentiments of others in this thread, that I make little use of my 'scope in radio servicing, but I do use it quite a lot for homebrew electronic projects. For radio restoration and fault diagnosis, in order of usefulness after digital and analogue multi-meters, I'd say signal injector/tracer, Chinese multi-tester, signal generator. I can't think when I last used my 'scope on a radio.

This is the way it ends up of course, when an experienced person is fixing a radio.

However, for a person learning, they can put the scope on connections in the local oscillator, see it changing with tuning the radio. Look at the modulation of the IF output at the input to the detector. Test the audio system, see any crossover distortion at the output etc and correlate that with what they hear. All of this helps them learn analog radio technology. Later, when they understand it like you do they can get away without the scope.

I managed most AM radio faults with nothing more than meter and a crystal earpiece, that was of course after I understood exactly how they worked.

Scopes do have more of a role in TV repairs than radio and for digital circuits they are very helpful. But it is still a very good idea that the OP has to help with fixing radios with the scope, at least initially, until experience catches up.

[cmjones01]

Originally Posted by Argus25

There seems to be a general feeling in this thread that analog scopes will be unreliable and need fixing.
...
So perhaps a good rule of thumb; analog scopes older than 1980 probably will need repairs, especially Telequipment.

Agreed. Analogue scopes can be amazingly tough. I have a pair of Tek 2465s which I bought, sight unseen, in a disposal auction in about 2003 (from John's Radio in Leeds, I think). They both worked perfectly. After another 10 years of heavy workshop use, one of them needed a replacement U800 (the infamous horizontal output chip). But that's it. They're both still in use today, one of them in front of me as I write this. No adjustments, no recalibration, nothing, and they're both still spot on for accuracy and performance.

I recently took a chance on a Tek 7904A (http://w140.com/tekwiki/wiki/7904) on offer at an absurdly low price from the US. It's a monster lab-grade plugin scope with 500MHz+ bandwidth, 1985 vintage. It arrived in a box full of polystyrene chips which had clearly had a big bump at some point on its multi-stop journey from the west coast of the US and been repaired with lashings of tape. I fished out all the polystyrene chips, switched on in trepidation and...it worked perfectly. I later gave the vertical gain a tweak, though. It was within spec but I knew it could do better.

These two examples are complex, thoroughbred instruments, but I think by the mid-80s the technology and manufacturing methods were sufficiently refined that they reached an amazing standard of ruggedness and reliability. That applies to all the big manufacturers, not just Tektronix.

Chris

[ms660]

I once worked for a firm where I was allowed to have a 'scope on my bench full time, made good profit for the service dept doing that, more often than not service dept's were money losers, I would never have been without it as it was in almost daily use by me, so fast, and you can see at a glance what's going on, a great learning aid and a great trouble shooting tool in the right hands.

Others might disagree.

Lawrence.

[Nuvistor]

I would never have been without it as it was in almost daily use by me, so fast, and you can see at a glance what's going on, a great learning aid and a great trouble shooting tool in the right hands.

I wouldn’t have been without my scope either, certainly helps get the sets fixed quickly and on to the next one.
Totally agree with you Lawrence, worth their weight in a busy workshop.

[evingar]

Another pro scope vote here.

I have a Tek 2456 on my home bench a along with a Fluke 25 as the 2 most used instruments. My test supply is fed through a variac and isolating transformer combo, so no problems about attaching earth clips to chassis.

I also have a Rigol DS1054Z. Given the state of the art of modern digital 'scopes I wouldn't hesitate in recommending one of these to a newcomer. Given that analogue 'scopes are all but extinct as new equipment, it really doesn't hurt to learn how to a Digital Oscilloscope and they are far less annoying than they were a few generations back.

[ms660]

Yes, in trade we were never allowed to hang about, PDQ results was the name of the game, I was lucky and managed to get day release to study City & Guilds R&TV servicing, initially without pay, then I threatened the boss with leaving, at which point he agreed to pay me my normal day rate for going on day release.

Lawrence.

[paulsherwin]

To return to the original question, the OP is asking about a cheap scope, not a £300+ professional instrument.

I agree that if you are going to get a scope as a radio repair beginner, a basic analogue scope is the best way to go. These are available for next to nothing. My Tek scope was a freebie and is a 1980s solid state mainframe job which must have cost a fortune originally. It came from a university Department of Zoology refit, and being a medical scope it doesn't have a lot of bandwidth, though it's fine for looking at noise on DC power rails which is the bulk of its use. Its main drawback is its weight and bulk, which is true of most ex lab professional scopes.

The OP still hasn't explained what he wants a scope for though. They aren't some sort of magical diagnostic tool. There is a danger that he'll spend all his time working out how to use his scope rather than understanding how radios work.

[Argus25]

Back to the OP and the original question.

I suggested the Hitachi V509 for the large number of reasons listed. But also that Hameg scope looks like a good option, especially if its readily available in the UK...although its bandwidth is less than the Hitachi's 50MHz and I'm not sure if it has a delay time-base and sync separators like the Hitachi ? making it very useful for TV work too.

Also I doubt that the screen energy is as high on the Hameg as the Hitachi with its 10kV applied to a 3.5 inch diagonal screen and the trace is easily seen in sunlight.

But this gets to another reason why the Hitachi is such a great economical little scope....it is fine for a beginner, or a professional. This avoids a problem that over the years I have come to call "The Fish Bowl Effect".

What happens here is that you buy a plastic goldfish bowl with a couple of fish in it, after 6 months or a year its not enough and you buy a bigger one, then after that three or 4 more and you end up with a big aquarium with a truckload of fish and a lot of support pumps and filters occupying half a wall.

If you can make just one purchase of something that is both economical enough but still much more than good enough, like the Hitachi V509 scope I suggested or the Hameg as others have suggested, it might just be that you never have to upgrade to another, so the money is very well spent.

(I would just bluntly say that you are wasting your time with those cheap scope kits for the reasons outlined in other posts, they are analogous to a very small goldfish bowl).

I also think using a scope on a radio will help you understand how the radio works.

[Argus25]

Originally Posted by cmjones01

I have a pair of Tek 2465s which I bought, sight unseen, in a disposal auction in about 2003 (from John's Radio in Leeds, I think). They both worked perfectly. After another 10 years of heavy workshop use, one of them needed a replacement U800 (the infamous horizontal output chip). But that's it.
Chris

Chris,

They probably are in a very precarious position by now with the Dallas DS1225 NVram batteries nearly exhausted. At the point where they malfunction, luckily the NV ram data is still just preserved and it is possible to extract that, if a battery is paralleled with the internal one. Otherwise a full calibration is required which requires the appropriate Tek generators which is very time consuming. The reason for this is explained in a detailed article I wrote on the topic and how these BBNVrams can be replaced with Fram:

http://www.worldphaco.com/uploads/TE...THE_DS1225.pdf

Unless yours are the type with the separate external ram batteries, then they will be ok.

[G0HZU_JMR]

Hameg do a few 100MHz analogue scope models as well. For example, I have a couple here stashed under the stairs. The model numbers are HM1004-3 and HM1007. The HM1007 is an analogue/digital combi model. The 1004-3 is a smaller and much newer scope but it is quite well featured and can be controlled via RS-232 although I doubt many would ever use this feature. It also has onscreen cursors and graphics. The user interface is a bit weird (to me at least) so this is one to avoid unless you need a small and newish/reliable analogue scope with a few modern features. If you search for images of this scope online you might think it is a pretty and functional scope. But I don't think it is as nice to use as a classic analogue scope because of the strange user interface.

Of the two I would recommend the older HM1007 but it probably isn't a scope for beginners because of the storage features it offers. It could get confusing to use because of these features. There are a lot of buttons on the front panel with unconventional labels! I've only used it a couple of times but it seems to be a decent general purpose scope. The alternative 100MHz model would be the HM1005 that doesn't have the storage feature. Scopes like this do turn up cheap fairly often so I would still advise patience unless you have a pressing need to have a scope as soon as possible.

[SiriusHardware]

The OP, Richard, asked for recommendations for scopes.

Others have already mentioned the Hitachi V212 and the Hameg HM2xx series - as it happens we have many examples of both at work and I would say that they are both great basic scopes, but the Hamegs do have one small advantage in that they include Hameg's favourite 'component analyser' feature which most other basic scopes do not have.

Although it takes a certain amount of acquired experience to interpret the results from this tool, especially on in-circuit components, it eventually becomes so useful that all of the team of techs where I work prefer to retain their old Hamegs rather than move up to something more modern.

I also much prefer a real analogue CRT scope to any digital scope masquerading as an analogue scope - it's just not the same at all for me.

With digital sampling scopes you can never be entirely sure whether any glitches or distortion you see are just down to the sampling rate or the pixel resolution of the dot-matrix display. With pure analogue scopes, what you see is usually what is really there. You don't have to worry about digital artefacts.

As an example, if you take a scope and feed a sinewave signal into it such that there are first two, then ten, then twenty, then thirty cycles across the screen it will probably look OK on both analogue and digital scopes. Slow the timebase down or increase the source frequency even more, and on an analogue scope the individual cycles will merge together into a solid band of blue or green, which is what you would intuitively expect.

Try the same thing on a digital scope and the display will usually become a mass of crawling dots...

[MrBungle]

Digital scopes haven’t done that for a number of years...