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Need a scope

Discussion in 'Shock Brother's DIY Amps' started by RollingBender, Apr 25, 2020.

  1. RollingBender

    RollingBender Tele-Afflicted Vendor Member

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    Cruised around Amazon and eBay a bit...looks like eBay has some nice old-school models at what seems like reasonable prices. Then I came to the realization that I don’t know what I’m looking for. I’d like to just buy once (but once, cry once).

    What would be a good make/model to try to track down?
     
  2. edvard

    edvard Tele-Afflicted

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    For older scopes, analog Tektronix are the classic workhorses and a sure bet when in good condition. For audio purposes you don't have to get the highest frequency model. The price generally follows the frequency and features. The most common models seem to be 100MHz, that's more than plenty. BK Precision and HP scopes are good too. Be aware those older scopes still use a CRT display, so it might be a good idea to look up spares while you're at it. I only looked briefly, but it looks like NOS spares are plentiful.

    For newer digital types, look for a good deal on Rigol scopes. I've seen them down to 50MHz, which is still more than plenty for audio purposes, and they have a reputation for being a reliable budget scope.
     
    Last edited: Apr 25, 2020
  3. moosie

    moosie Doctor of Teleocity Silver Supporter

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    I bought this Siglent a couple years ago. I knew nothing, still know quite little, and in fact I ended up not keeping it, because I figured I'd not use it enough (I have since regretted that decision at least 20 times).

    It got the approval of a very knowledgeable forum member who helped me use it to tune my ReVibe build. It was everything we needed for that job, and probably more.

    At $250, I was happy as a clam. Plus, I may have got it $50 off, via a coupon... I mention this in case that deal still exists...

    My tech friend had a Rigol, and thought this Siglent was a fine choice. Perhaps @edvard would care to comment on it. I know it was cheaper than the comparable Rigols.
     
  4. edvard

    edvard Tele-Afflicted

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    I haven't heard anything bad about Siglent scopes, and if they're comparable to a Rigol at a better price for brand new, then all the better.
     
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  5. mally

    mally Tele-Holic

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    HaHa I thought
    [​IMG]
     
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  6. Kevin Wolfe

    Kevin Wolfe Tele-Meister

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    Is it true that the high voltage probes are where the “real” money’s spent?
     
  7. moosie

    moosie Doctor of Teleocity Silver Supporter

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    I think so, yeah. But unless you're analyzing power supplies, amp work shouldn't require it.
     
  8. Peegoo

    Peegoo Poster Extraordinaire

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    I got rid of my old Tektronix analog about four years ago and picked up a new Rigol. Couldn't be happier.

    Always remember the probe ground is at mains earth ground. This sometimes bites new scope users in the tokhes; it can make the magic smoke escape from a circuit or blow up the scope.

    Look here:

     
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  9. kbold

    kbold Tele-Afflicted

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    First you need to decide what you want it for.
    This will help you determine what features suit.
    Mainly you want to decide on:
    - number of channels (usually 2 or 4)
    - analogue or digital (digital will give you storage and advanced math functions, and some have spectrum analysis).
    - desired frequency range

    Many brands out there: most of them are good.
    My personal recommendation would be a 2nd hand Tektronix digital storage CRO. 50Mhz frequency range should usually be plenty.
    Think of Tektronix as the CRO equivalent to Fluke multimeters.
    There are some better and more expensive, and a lot more not as good but cheaper.
     
  10. brokenbones

    brokenbones Tele-Holic

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    Others have given you good basics on what to look for when buying an old scope. My advice is that if this just a part time hobby, you don't need to spend too much. You're going to want an isolation transformer and signal generator too. A good source for used, quality scopes and signal generators are college surplus stores.
     
  11. sds1

    sds1 Tele-Afflicted

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    I have 2 older ones that I got used, cheap. But I wish I had just gotten one of the cheapest digital ones (Rigol, Signlent, whatever), brand-new to start with...

    The problem with those older scopes is they are like tubes amps, performance of power supply etc deteriorates with age and then maintenance is required. You want nice sharp traces, etc. and you want to be able to rely on your test/diagnostic gear not question it.

    Anyhow, IMO if you have the loot get one of those Amazon dealios.
     
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  12. moosie

    moosie Doctor of Teleocity Silver Supporter

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    I'm coming at this from the other angle - the newbie angle. Not sure if the OP is like me or not. Instead of investing in yet another device, I was able to complete my testing with a signal generator app on my phone, and a 1/8" to 1/4" male to male cable. Made one of those signal tracers, too, with a capacitor, a nail, and some heat shrink tubing. It was all plenty for my amp-building needs.
     
  13. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    where SW are you? Seems that you can get older tektronix around the cities for 70-90 dollars typically. As for the signal generator, those typically are free like moosie mentions.
     
  14. galaxiex

    galaxiex Tele-Afflicted

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    I get by with this...

    scope 002.jpg

    All tube....

    :)
     
  15. Paul G.

    Paul G. Friend of Leo's

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    Old CRT oscilloscopes are cool and all, but they're old and will need maintenance. If you're up to it, good. Although cheesy and plasticky, newer digital scopes should be fine for years of use. If you can get a Tektronics or similar for cheap, by all means, but I wouldn't spend a ton of money on one.

    For amps you don't need a lot of bandwidth and 2 channels is plenty. $300-$400 should buy something nice.

    Being perpetually short of cash, I got a Hantek 6022BE USB scope ($60) as a temporary measure. It uses your laptop (or Android tablet with additional software) for control and display, and the probes are OK for amp work. It's a bit cheesy, and clunky to use touch pad for control rather than easy knobs, so I'll replace it as soon as I get the scratch, but it is quite adequate.
     
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  16. FenderLover

    FenderLover Poster Extraordinaire

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    I have a Tek 466 on my bench. Nice scope, but it's freakin' huge. If it dies, I'll look for digital. They're built so well that when it does finally die, digital may be my only choice anyway.
     
  17. Nickfl

    Nickfl Friend of Leo's

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    I've got an old Leader branded analog scope I got on ebay for $80, it was basically NOS in the original box with all accessories. It is more than adequate for amp work, but when it craps out (when not if, as it is 40+ years old) I'll probably go for a digital scope like that amazon link. IMO, even the "best" old analog brands like Tektronix are old, obsolete, bulky and not worth the cost or effort of repairing or calibrating. I wouldn't pay more than $100 for any old scope (and people are asking stupid money for some of those Tektronix scopes on ebay). If you want to buy once, you should probably buy an entry level digital scope new or see if you can find a fancy one surplus (hospitals and labs replace stuff like than all the time).
     
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  18. printer2

    printer2 Poster Extraordinaire

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    We had a bunch of Leaders at the college when I was a Tech. Basic but could do what is needed for audio work. Had a bunch of Tektronix, B&K, I have a 1541. My favorite to use when I was at the school was a Panasonic.
     
  19. LudwigvonBirk

    LudwigvonBirk Tele-Holic

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    Rigol 1054-series (I have the “Z”) is a great pick for lower-powered amp work, and will do everything you really need. Under $400 bucks new.

    Yes, the Tektronics and etc analog scopes were great in their day but I wouldn’t go there now, no matter the price. Those are like buying a ‘73 Trinitron TV- you actually don’t want it even if you think you might. And then try getting rid of it without breaking any laws!
     
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  20. tubeswell

    tubeswell Friend of Leo's

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    You don't need high MHz for the audio work involved in guitar amps. Anything up to 10 or 20MHz is plenty. (Modern scopes are way higher freq than this). Two channels is handy for analysing input and output simultaneously, but for repairs you can get by with a single channel unit (if all you're doing is looking at the speaker output with a jenny on the input).

    The choice of probe is important, and you don't want to skimp on quality. A high insulation-rated passive probe with a choice of clips that you can attach is handy. A 1X probe is sufficient for measuring speaker signal, but 10X probe is handy for high frequency stuff. You can get switchable 1X-10X probes.
     
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