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Old 31st December 2012, 10:01 PM   #11
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I'm in exactly the same boat. Last time I was into diy electronics I'd built my own Heathkit oscilloscope from a billion individual parts and it was never worth a darn, not very stable, not very good focus, no storage, no automatic measurements. I've been shopping ever since. I have bids on eBay right now, and I often get outbid on what I really want, so I'm not going to say too much more to my competitors until I buy.

I want something better than PC sound card software. A USB adapter might suffice but I'd want more real knobs than they usually provide. The handhelds don't have much of a display, so I'd usually use them as a USB adapter type anyway, but with a few more controls. I hate up/down buttons for sensitivity and time, I can swing a knob back & forth once and then go directly where I want it, but usually buttons suck. The ones that look like an old analog but are only a few inches deep seem nice. I like the huge storage memory of the digital scopes so I can replay to measure, and I really like the big display capabilities of the really good digital scopes connected to a PC. A 200mhz digital scope with fast sampling looks just fine to me, and its always in focus, but the good stuff is expensive. Two scopes, one good digital and one good amalog, might seem ideal, but I think if you put that kind of total money into one good digital it might make the analog redundant.

There's other considerations using 'scopes for working on tube circuits. I have a gift for blowing out "indestructable" test equipment. A second set of more appropriate high-voltage very-high-impedance probes. Maybe a third set for looking at the motorcycle's ignition output? Completely isolated true differential inputs where neither has any reference to ground is a really handy feature when you want to record two traces of only a few volts AC each, including showing a DC component, but which are 500+ volts away from each other or ground. Some scopes feature inputs that are optically isolated; they sure don't achieve 200+mhz by blinking an incandescent bulb for the opto-isolator so I assume they must use some kind of LED or lazer? At various times I've done despicable things like floating my entire 'scope and breadboard off any ground via isolation transformers, then found myself afraid to touch a plastic knobs for fear of a deadly 500-volt jolt off the faceplate or from a setscrew in the knob finding my body an attractive ground. My dad used to have long probes with insulators that looked like they should be hanging from a power pole.

Last edited by cyclecamper; 31st December 2012 at 10:05 PM.
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Old 2nd January 2013, 05:11 PM   #12
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Well, somebody out-bid me. Good thing I guess, I really should pay down bills first. I've got two VTVMs to refurbish first anyway.

If you search around, you can find the favorite classic analog Tektronics scopes of the guys who repair & refurb them. Too early and the Tektronix are enormous, tube, less stable, need frequent calibration, and parts can be difficult to get. The more recent use a lot of application-specific integrated circuits which are only obtainable now by salvage out of other scopes. Just like there's a 'classic' tube amp era that's easy to work on yet uses reasonably modern components, apparently the same is true of oscilloscopes unless you want a disposable 'scope. There are classic models which are wonderfully stable, yet easy to work on. Then you just get a used one with a good bright well-focused picture on the tube.

Last edited by cyclecamper; 2nd January 2013 at 05:27 PM.
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Old 2nd January 2013, 05:20 PM   #13
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when I was an electronics student we had VTVms on the bench in lab. Hickoks as I remember. You had to calibrate the needle at both ends...OFTEN
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Old 2nd January 2013, 07:17 PM   #14
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this looks at least to be a decent deal. any thoughts?

Tenma 100MHz Dual Channel Digital Storage Oscilloscope | 72-8385 (728385) | Tenma
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Old 2nd January 2013, 07:24 PM   #15
Mooly is offline Mooly  United Kingdom
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Very nice but.... I'd take a good analogue scope of even a quarter the bandwidth everytime
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Old 2nd January 2013, 07:30 PM   #16
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why is that by the way?

BK Precision has mostly analog scopes and I have been looking at them also.
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Old 2nd January 2013, 07:41 PM   #17
Mooly is offline Mooly  United Kingdom
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Because an analogue display lets you winkle out the finest detail limited only by the trace thickness. The digital display commonly suffers from digital artifacts a bit like pixellation.
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Old 2nd January 2013, 07:48 PM   #18
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makes sense...thanks for the guidance
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Old 2nd January 2013, 11:29 PM   #19
Enzo is offline Enzo  United States
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And for audio, you really do not need 200MHz of bandwidth.
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