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| H713:
One of the problems that modern scopes have, in my mind, is that they try to do everything. That's what can them such a chore to use for normal scope operations, for the same reason that an old cell tower service analyzer is a real chore to use as a spectrum analyzer. It's like Windows - MS throws everything in the kitchen sink, along with lots of buzzwords into their release, and the result is that it is awful at everything. The idea of adding a logic analyzer to a scope is sound - stuff these days is usually mixed signal anyway. In my experience, however, the screen real estate on most scopes is quite limited, and it ends up being miserable to use. The FFT on a scope remains a pathetic substitute for a spectrum analyzer. Would you buy a 500 MHz spectrum analyzer with 8 bit dynamic range? Didn't think so. It's a nice feature for interpreting goofy waveforms, and maybe some crude EMI debugging in a pinch, but that's the total extent of its usefulness. The additional hardware required by a signal generator, however, is considerable. It's a whole new device being added, and there's no good reason for it to be in the same box. It's too frustrating to use two-in-one or five-in-one devices of this nature - ditto for DVMs. If you cram a signal generator into a normal scope envelope, you inevitably make a serious sacrifice. Even if the electrical performance is acceptable, the UI won't be. |
| H713:
--- Quote from: tautech on December 19, 2022, 07:51:56 pm ---It is however when you need to invest in a working scope one need consider if what's available is a worthy investment. Old stuff is just that, old and nearing the end of that bell curve of reliability where the novice especially isn't well served by some unreliable junk that needs a duplicate to help fix it. Often that novice, a new Uni student is more focussed on projects and studies rather than need fix some old boat anchor. Here in NZ there is not the resources of old scopes in working condition and why would a budding engineering student even want to use one when at Uni they are to use better, much better. --- End quote --- What are you doing to these things to make them so unreliable? I'm trying to remember the last time I've witnessed an analog scope fail. Usually the ones that need fixing are the ones that have been worked on to the nth degree by someone that decided to replace every capacitor in sight. By far the least reliable scopes I've seen are some of the old Rigols (and Rigols with an Agilent sticker on them) that seem to have chronic encoder problems. |
| tautech:
--- Quote from: H713 on December 20, 2022, 08:02:13 am --- --- Quote from: tautech on December 19, 2022, 07:51:56 pm ---It is however when you need to invest in a working scope one need consider if what's available is a worthy investment. Old stuff is just that, old and nearing the end of that bell curve of reliability where the novice especially isn't well served by some unreliable junk that needs a duplicate to help fix it. Often that novice, a new Uni student is more focussed on projects and studies rather than need fix some old boat anchor. Here in NZ there is not the resources of old scopes in working condition and why would a budding engineering student even want to use one when at Uni they are to use better, much better. --- End quote --- What are you doing to these things to make them so unreliable? I'm trying to remember the last time I've witnessed an analog scope fail. --- End quote --- Just using them. At one time my hobby was repairing and selling scopes, any scope that could be found cheap that preferably had manuals available online or they came with them but schematics was a must ! It first started with an English Telequipment D83 given by my mentor that only required a NTC thermistor for the LV primary side EHT inverter but went onto be somewhat unreliable even though that model were made after Tek had acquired Telequipment and it had such a nice CRT the same as Tek used in their 7603. Last scope to sell. After that was a HP1740 that had numerous issues including the common terrible cracked solder joints on the PCB connector plug. ::) In the meanwhile I was starting to look at DSO's and saved myself from buying a UNIT DSO but instead a Tek TDS2102B. :phew: Had been looking at GW Instek but they were overpriced locally. The Tek became my main scope allowing for accuracy comparisons after repairs of CRO's of which there were a few more: Aussie BWD Tek 500 < Gorillas been inside. Love job for the mentor. English Bradley < EHT transformer secondary winding open, white silicon potted in ferrite pot core on the first layer. :phew: Lost just 2 turns so adjusted to spec just fine. Then a couple of DSO's were scored, an infamous TDS210 with the typical busted input BNC's and the need to check it wasn't a recalled SN#. New BNC's and custom mods for it to never happen again. :horse: Later a monochrome 60 MHz TDS1002B IIRC with a dead backlight in which the RC for the backlight push/pull oscillator had lost all its C and was just a few pF's ! :-DD A 60c TH 330nF cap fixed it for a darn good profit as I'd been given it by an EE friend that couldn't be bothered to fix it and instead brought a new Tek. ::) The BWD was also sourced from a tech, a TV tech that obviously didn't know where to start as it came with full manuals and like many old Teks suffered from Tants used too close to their voltage rating. ::) Another easy fix. :) Lessons learnt were there is some circuitry in CRO's that's under stress particularly within the EHT that can't be ignored and mostly is the cause of a not quite right CRO and due to the elevated voltages and not an area the general EE is comfortable working on. Like it or not, this you just can't escape EHT with CRO design and to some degree with early DSO's too that used CCFL LCD backlight. With these some years of hands on experience I went looking for competitively priced DSO's in brands that at that time were not represented in NZ and by luck teamed up with Siglent very nearly 10 years ago shortly after which the TDS2012B gave up the ghost in protest. :-DD It sits unfixed in a box as penance for letting me down where its failing was convection cooling using a top vented chassis allowing crud to settle on IC pins and our humid climate did the rest......another lesson learnt, you can stick your convection cooled equipment where the sun don't shine ! And some accuse me of insufficient experience. ::) |
| vk6zgo:
--- Quote from: tautech on December 20, 2022, 09:22:37 am --- It first started with an English Telequipment D83 given by my mentor that only required a NTC thermistor for the LV primary side EHT inverter but went onto be somewhat unreliable even though that model were made after Tek had acquired Telequipment and it had such a nice CRT the same as Tek used in their 7603. Last scope to sell. --- End quote --- A while after Tektronix bought Telequipment, I notice that those Tektronix modules assembled at the old Guernsey factory had a noticeably larger percentage of niggling faults than the ones from Beaverton. It seems that instead of Telequipment getting better, Tektronix got worse! This was only for about a year, after which, they seemed OK. That said, Tek could make crap, as witness the 650 series Picture Monitors. They were truly dire, although they had some strong competition in that category, with the field containing such merdé as some of the Philips things, or the truly gigantic all vacuum tube PAL colour monitor from Blaupunkt that Telecom Aust bought in the early 1970s. |
| tggzzz:
--- Quote from: tautech on December 20, 2022, 09:22:37 am ---And some accuse me of insufficient experience. ::) --- End quote --- Mirror ::) |
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