why do they still make analog oscilloscopes - Page 1
Forum section: electronics / testgear

author: electronics man
author_rank: Frequent Contributor
timestamp: May 06, 2014, 08:34:44 pm
content: why do some manufacturers still make analog oscilloscopes, i could understand some small, niche manufacturer making them but theses are cheep chinese companieshttp://www.rapidonline.com/Test-Measurement/GW-Instek-GOS-6000-Series-of-30MHz-Analog-Oscilloscopes-518850.so?

author: Excavatoree
author_rank: Frequent Contributor
timestamp: May 06, 2014, 08:39:39 pm
content: Because they are less noisy than digital scopes.*ducks*

author: Hydrawerk
author_rank: Super Contributor
timestamp: May 06, 2014, 08:39:56 pm
content: Because people buy them. Sometimes you need an intensity graded display but only 30 MHz bandwidth. Then the cheapest option is an analog scope.

author: c4757p
author_rank: Super Contributor
timestamp: May 06, 2014, 08:41:01 pm
content: GW Instek is no Tektronix or Agilent, but they're no Wun Hung Lo either.Beats me - educational market? It's not a bad scope, though the bandwidth is kind of sad. At least it has the "digital" features that the analog scopes had at the end of their time - cursors, frequency counter, configuration save/recall...

author: Neilm
author_rank: Super Contributor
timestamp: May 06, 2014, 08:41:15 pm
content: Quote from: Excavatoree on May 06, 2014, 08:39:39 pmRats - beaten to it

author: free_electron
author_rank: Super Contributor
timestamp: May 06, 2014, 08:46:16 pm
content: Quote from: Excavatoree on May 06, 2014, 08:39:39 pmthat's it, duck hunting season is open, and i got my jar of orange glaze ready...

author: electronics man
author_rank: Frequent Contributor
timestamp: May 06, 2014, 08:49:19 pm
content: Quote from: Excavatoree on May 06, 2014, 08:39:39 pmbut are they?

author: nctnico
author_rank: Super Contributor
timestamp: May 06, 2014, 09:01:27 pm
content: Quote from: electronics man on May 06, 2014, 08:49:19 pmNot really. The noise just doesn't show. Vertical deflection needs quite a bit of amplification so there is a big chance to add a lot of noise on the way. Most digital scopes have averaging and/or high resolution to filter noise (some even with variable filters) so you can clean up a signal.

author: EEVblog
author_rank: Unknown
timestamp: May 06, 2014, 09:47:29 pm
content: Some people still prefer the analog intensity graded display and no-fuss operation, and hiding all that uncorrelated noiseObviously a market for them.Perhaps still some education market left too? Old time teachers who think it's best to learn on an analog. I don't blame, I think they are still excellent learning tools.

author: georges80
author_rank: Frequent Contributor
timestamp: May 06, 2014, 09:52:48 pm
content: More likely they have a stockpile of old CRTs that they would rather have in your landfill than theirscheers,george.

author: John Coloccia
author_rank: Super Contributor
timestamp: May 06, 2014, 10:46:33 pm
content: Because some of us are still doing things like analog audio work, and to get a digital scope that will show me what I need to see is thousands of dollars but I won't use but a fraction of the bandwidth and features. For digital, again all I need is a dirt cheap digital scope. Both together is a fraction of what I'd pay for one scope that will do it all.

author: AG6QR
author_rank: Frequent Contributor
timestamp: May 06, 2014, 11:18:14 pm
content: They've still got some advantages over digital scopes. No "dark time" in x-y mode, no aliasing, intuitive intensity graded display, among others.Sure, digital scopes have their own advantages, and for many jobs, a DSO would be preferable. But not always. Lots of people prefer to keep at least one analog scope around.It's not at all surprising that people still have occasional tasks where an analog scope works better than a DSO. What is kind of amazing to me is that new analog scopes can be sold in today's market when they have to compete with all of the old used analog scopes out there, available so cheaply. There are some old high-end scopes available today for a tiny fraction of their original cost. I guess some people want something new with a warranty, even if it's not as capable or well built as what's available on the used market.It's like if you wanted to build a 35mm film camera today. Your major competition isn't the new digital cameras being made today, but the glut of old used professional quality film cameras that are available for peanuts today, after so many professional photographer switched to digital. There are still a few 35mm film cameras made now, but not very many.

author: MadTux
author_rank: Frequent Contributor
timestamp: May 07, 2014, 12:42:09 am
content: I fully agree, analog scope market is oversaturated and you can get goodies such as Tek 2465; 7854 7904(A) or high end Hamegs for very little money, so it's kinda stupid to make new analog scopes with crap specs.For everyday use, I wouldn't trade any of these mentioned above for a new rigol or even one of those Tek junk scopes with 2kB of CCD-memory. Reasons for that are:-Instant beam, no boot time, no stupid menus, there's a knob for everything so much faster to use-you see what's really there no ADC artifacts, aliasing or undersampling-usually displays and triggers on signals well beyond their specs, do that with a digital one-quality that will outlast any china crap-analog stuff is relatively easy to repair and rarely fails compared to (new) digital circuits and I like to keep my equipment working myself, furthermore the documentation is usually excelent compared to new equipment-a plugin for about everything in the 7k series like the 7A13 (my everydays favorite since it combines voltmeter and scope); ADC for slow non repeating signals (7A22) in the 7854The only time I really miss a truely new DSO with deep memory is when I'm working with serial buses or need to look on the analog properties of a digital signal. Everything else can be handled (better) with an analog scope or logic analyzer

author: electronics man
author_rank: Frequent Contributor
timestamp: May 07, 2014, 07:04:33 am
content: I just think digital scopes are much easier to use, they are also much better for analysis.

author: rf-loop
author_rank: Super Contributor
timestamp: May 07, 2014, 07:23:10 am
content: Quote from: electronics man on May 06, 2014, 08:34:44 pmAnalog scope have many advantages (of course also disadvantages)With totally unknown signal one disadvantage with digital scopes is aliasing.If look price and aliasing - well this is one reason. And only one. There is of course also many other reasons.I have find in my work that sometimes need digital scope and some times still analog is very handy.(of course I mean real (and old) professional analog scopes like Tek and HP)

author: tszaboo
author_rank: Super Contributor
timestamp: May 07, 2014, 08:58:27 am
content: They make them, so Linear Technology can still put new pictures in their datasheets and application notes.

author: electronics man
author_rank: Frequent Contributor
timestamp: May 07, 2014, 12:45:49 pm
content: I do find xy mode is better on analog scopes than digital

author: madshaman
author_rank: Frequent Contributor
timestamp: May 07, 2014, 03:05:40 pm
content: An analog scope, like its digital counterpart, graphs voltage over time, but it's an inherently different instrument/tool (please noone jump in with DSOs that use internal CRTs, that will just confuse things :-p).I honestly could never see myself having less than two analog scopes on my bench, no matter what my budget. And you certainly won't see me give up my DSOs any time soon.It's very close to apples and oranges for me.Most larger companies can afford DSOs that will give you almost everything a CRO can, and even Rigol's mid-range scopes come close at a reasonable price, but cheap DSOs are almost useless; a cheap CRO can be *very* useful.That's just an opinion, it's hard to say why they're still manufactured.

author: electronics man
author_rank: Frequent Contributor
timestamp: May 07, 2014, 03:11:39 pm
content: CROs cant do nearly as much analysis as DSOs can thats why i wouldnt waste my money oon a CRO as i wouldnt have much use for it as CROs have a much more general perpose use. for things like digital signals a CRO is useless. thats why my first O scope is a Rigol ds1074z

author: c4757p
author_rank: Super Contributor
timestamp: May 07, 2014, 03:30:40 pm
content: Use care when applying the word "useless", as its meaning is rather final. An oscilloscope isn't really the right tool for viewing the data of a digital signal anyway, you want a logic analyzer for that. And an analog scope is perfectly good for viewing theoscillatory part of the waveform - edges, etc.No good for catching rare runt pulses either, but lots of DSOsalsosuck at that.

author: pickle9000
author_rank: Super Contributor
timestamp: May 07, 2014, 03:46:35 pm
content: As long as they can make a fair profit on them someone will continue to make them.

author: electronics man
author_rank: Frequent Contributor
timestamp: May 07, 2014, 07:16:26 pm
content: Quote from: c4757p on May 07, 2014, 03:30:40 pmwhy do they make oscilloscopes with serial decode function? therfore an oscilloscope is the right tool for analysing digital signals.

author: Fsck
author_rank: Super Contributor
timestamp: May 07, 2014, 10:41:58 pm
content: Quote from: electronics man on May 07, 2014, 07:16:26 pmWhat's the point of having serial decode on say.. a rigol 2k series scope? 2 channel decode isn't particularly great.the same reason you can do FFT on a scope but there are spectrum analyzers.not everyone needs the cost+power(+has space) of dedicated hardware. the scope (many, if not most models) is basically becoming a multitool, lots of features but nothing mindblowingly good, doesn't mean they're not still useful.I'd probably still take a 2465 over a ds1074z.

author: jancumps
author_rank: Unknown
timestamp: May 07, 2014, 10:55:44 pm
content: Quote from: madshaman on May 07, 2014, 03:05:40 pmShame. I have one of those and I'm ready to jump in

author: vk6zgo
author_rank: Super Contributor
timestamp: May 08, 2014, 06:57:01 am
content: Quote from: rf-loop on May 07, 2014, 07:23:10 amIn repair situations,a common procedure with an analog Oscilloscope is to:-(1)Set the 'scope Vertical input to “DC coupled",& the triggering to “Auto”-----in this setting,the instrument will “free -run”,displaying a flat line on the screen without any input.(None of the DSOs I've ever used really had any equivalent to this function,as “Auto” was a completely different thing)(2)Look at various parts of the circuit to determine the presence or otherwise,of the desired signal,dc power supplies,spurious signals,etc.(At this point,proper triggering is not necessary)(3)Trigger 'scope correctly on the signal of interest,for detailed examination.A Tech may fault-find a piece of equipment without using any other instrument although,usually a DMM is used to verify the power supply voltages more exactly,before "closing everything up".I found it was very hard to follow this procedure using a DSO,as the only way to look at a dc level seemed to be to put the 'scope in “roll”.Even this didn't work well,as it displayed the voltage change as the probe was placed on the test point as a transition,which may or may not be on a visible part of the display.No doubt,modern DSOs have overcome such limitations,but the early versions have left us “Greybeards” with a somewhat jaundiced view of such devices.I was an early enthusiast for the idea of Digital Oscilloscopes,but the reality set me back on my heels!Ultimately,"It's horses for courses".If you are looking for a "runt" pulse in a pulse train,then the DSO is the obvious choice.If you are not even sure if the pulse train is there,or if it is riding on a few volts of AC mains hum,I'd go for the analog Oscilloscope!

author: KedasProbe
author_rank: Frequent Contributor
timestamp: May 08, 2014, 07:05:36 am
content: They still make analog scopes so DSO designers have a reference about how the signal is supposed to look like on the LCD sceen

author: fcb
author_rank: Super Contributor
timestamp: May 08, 2014, 07:46:53 am
content: Quote from: electronics man on May 06, 2014, 08:34:44 pmsimple - because people buy them

author: zapta
author_rank: Super Contributor
timestamp: May 08, 2014, 08:08:36 am
content: When you think about it, all oscilloscope are analog. The voltage vs time graph on a digital scope is still analog (compare with a analog vs digital multimeter where the display of the later is indeed digital).

author: KedasProbe
author_rank: Frequent Contributor
timestamp: May 08, 2014, 08:26:17 am
content: Quote from: zapta on May 08, 2014, 08:08:36 amIt's a DSO because the signal is processed digitally.Holding your tong on the VGA out cable of a DSO still doesn't make it an analog scope

author: zapta
author_rank: Super Contributor
timestamp: May 08, 2014, 12:28:22 pm
content: Quote from: KedasProbe on May 08, 2014, 08:26:17 amThe time and voltage representation on the display in a graph form is analog.

author: VK5RC
author_rank: Unknown
timestamp: May 08, 2014, 11:24:18 pm
content: As a good digital scope fan, I would propose 'all scopes are digital " as photons, eye photo-receptors, the optic nerve and neurons are all binary or quantized.Please don't take this too seriously :-)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 09, 2014, 12:02:18 am
content: Quote from: VK5RC on May 08, 2014, 11:24:18 pmThe phenomena may be quanta, but the probabilities aren't even analog, but complex numbers!Tim

author: dannyf
author_rank: Super Contributor
timestamp: May 09, 2014, 12:09:33 am
content: QuoteBut your analysis is spot on.

author: echen1024
author_rank: Super Contributor
timestamp: May 09, 2014, 02:12:56 am
content: They still make high-end Tektronix 2465 cotemporaries as well.The Iwatsu SS-7847, 470MHz analog scope. A steal at only $17khttp://www.tequipment.net/IwatsuSS-7847A.html?v=7402

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: May 09, 2014, 03:29:38 am
content: Hi,If I could only have ONE scope I would chose either a Tektronix 2232 or a Philips Combiscope.Both of these can operate as either analog scopes or digital storage scopes at push of a button.I like the analog mode for trouble shooting and the digital mode for measurement. These are advance analog scopes with readout and cursors.I started with a Tektronix 545 tube scope. I was given this as 'BER' Beyond Economical Repair, I bought a parts unit to get some spare tubes and a got it working.This scope had a 4 x 10 cm graticule. The 545 was built in 1955 and 1959. I was given it in 1979. Tektronix scopes built before the mid-60s had UHF connectors (PL-259 , so-259). This 545 scope features like dual-timebase, intensified sweep. The bandwidth was 24 MHz with a CA dual input plug-in.The next scope that I got was an HP180 mainframe with 50 MHz plugins. I like the flood gun illumination on the HP scope, great for taking polaroid photographs.After this I graduated to a Tektronix 7603 with 7A26 and 7B53 plugins. I also bought a 7D20 digitizer for this mainframe. 40Msps and 70 MHz BW. I did a lot of good stuff with this scope.I have had nearly all the models in the 7000 series. I have had TDS460, TDS 500 series and TDS 700 series.These days I typically have a TDS 744A or a TDS 754A scope on a my bench.I think the analog scopes are great for academic use, where the waveforms are continuous. A soon as you need to look at single shot events then digital is definitely the way to go.Regards,Jay_Diddy_B

author: David Hess
author_rank: Super Contributor
timestamp: May 09, 2014, 05:51:34 pm
content: I agree about the 2232 (or 2230). Those are my go-to oscilloscopes for general work and they have peak detection which the low end Rigols still lack. When I need real frequency and pulse measurements that may or may not be gated, I break out the 2247A or 7D15. When I need automatic measurements, a pretrigger record, low repetition rates, or waveform storage, then I use a DSO although the 2232 can do all of that except automatic measurements.Quote from: MadTux on May 07, 2014, 12:42:09 amThe Tektronix CCD oscilloscopes or at least the early ones with peak detection are pretty good and compare favorably with modern "low noise" DSOs once you get past their non-graded displays. I would prefer a short record length with higher waveform acquisition rates than a long record length although the Tektronix CCD designs are slow. Where they suffer is aliasing caused by interleaving of the digitizer but modern DSOs also have that problem to one extent or another if they are implemented that way.The user interface is generally better; I do not have room on my workbench for another keyboard and mouse. They show a more realistic representation of the signal without a bunch of different modes with inadequate documentation.I like the 7A13 because it is a great differential input amplifier with slideback capability which puts modern DSOs and most differential probes to shame.As far as the noise issue goes, look how much trouble Dave had to go to to compare them. That is *not* an advertisement for ease of use or understanding of DSOs. Even worse, too many low end DSOs lack intensity grading which both makes them look worse *and* make them useless for measurements where visual noise matters. The ones that do support intensity grading often do a poor job of it.

author: Stonent
author_rank: Super Contributor
timestamp: May 09, 2014, 06:36:55 pm
content: Quote from: EEVblog on May 06, 2014, 09:47:29 pmIt took me almost a day to something to show up on my analog scope when I first got it. I thought it was dead. No auto button to do it all for me.I suppose if you're used to auto trigger, auto time-base, auto volts/div. You could miss when the scope just "autos" something and make a wrong measurement.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 10, 2014, 12:23:03 am
content: AUTO button! Scourge of the engineer! I am highly tempted to remove them, particularly the most accidentally-touch-prone ones, in the most physically gruesome way possible!Tim

author: David Hess
author_rank: Super Contributor
timestamp: May 10, 2014, 03:28:30 am
content: My 2440 (DSO) and 2247A (analog) have automatic setup buttons but the only time I use them is to reset the oscilloscope to a known state.

author: zapta
author_rank: Super Contributor
timestamp: May 10, 2014, 04:12:03 am
content: Quote from: VK5RC on May 08, 2014, 11:24:18 pmIf your eyes only count the total photons then yes but they also assign x/y values to each photon which represent time and voltage respectively.Quote from: VK5RC on May 08, 2014, 11:24:18 pmToo late. ;-)

author: VK5RC
author_rank: Unknown
timestamp: May 10, 2014, 06:02:49 am
content: Re x-y data, that is also digitalised in humans as the photoreceptors 'pixelate" (i am sure that is not the correct term) the data in the x-y plane as well! The post data processing in the occipital lobe is the clever bit! One "you beaut" fpga multi_channel processor :-)

author: zapta
author_rank: Super Contributor
timestamp: May 10, 2014, 07:05:16 am
content: Quote from: VK5RC on May 10, 2014, 06:02:49 amIf so, I have a digital oscilloscope for sell ;-)

author: madshaman
author_rank: Frequent Contributor
timestamp: May 10, 2014, 08:50:29 am
content: Quote from: T3sl4co1l on May 10, 2014, 12:23:03 amSeriously? What's wrong with hitting auto and twisting a knob or two twice instead of twisting a knob or two a bunch of times.Honestly, I can't imagine anyone who knows how to use a scope becoming reliant on auto-scale...Why would you remove a useful feature?

author: electronics man
author_rank: Frequent Contributor
timestamp: May 10, 2014, 10:11:17 am
content: I never use auto on my DSO i have no need to.

author: John Coloccia
author_rank: Super Contributor
timestamp: May 10, 2014, 11:03:33 am
content: How do you find an unknown signal without the auto trigger? Do you just randomly twist knobs until you see something blip on the screen? It seems like a pretty useful and practical function to me.

author: c4757p
author_rank: Super Contributor
timestamp: May 10, 2014, 11:10:16 am
content: Quote from: John Coloccia on May 10, 2014, 11:03:33 amRandomly? No. How often is a signal truly unknown? I'd rather know the scale factors the scope is set to without having to stop and read them. I've usually got a pretty good idea what kind of signal I'm going to be looking at, so I set up the scope before I start. Then I can zoom in or out if I see something interesting.

author: John Coloccia
author_rank: Super Contributor
timestamp: May 10, 2014, 02:04:59 pm
content: Quote from: c4757p on May 10, 2014, 11:10:16 amWhen I'm debugging a board that doesn't work, quite often actually. I can have a tiny little AC signal...or I can have something sitting on a rail....or anything in between. I'm baffled why a pro would waste time twiddling around when you can simply zoom out, hit auto, see what you have, and then zoom right in on it with proper triggering. Considering all the beginners on this board, it seems like it's doing them a disservice by filling their heads with the idea that auto triggering is somehow bad or amateurish.

author: w2aew
author_rank: Super Contributor
timestamp: May 10, 2014, 02:11:50 pm
content: Quote from: John Coloccia on May 10, 2014, 11:03:33 amRemember that auto-trigger does automatically setup the trigger setting for you. It is simply a timeout circuit. If a valid trigger event is not found in 50ms or so, it initiates a trigger on its own. This keeps the trace active while you hunt for your signal.So, auto-trigger is very useful, and not in the same category as the Autoset feature. Autoset attempts to change vertical, horizontal and trigger settings to put a waveform on the screen.If you didn't have auto-trigger, you could use something line trigger to keep a waveform triggered on screen so that you could set the vertical controls properly on your signal, then switch the trigger source to the channel of interest.

author: madshaman
author_rank: Frequent Contributor
timestamp: May 10, 2014, 04:53:46 pm
content: Auto-set (depending on your scope) can do more than just setting the time-base, triggering and scaling.For example, if I've been using two channels and moving things around, then I hook up four channels, I just have to make those extra channels active then hit auto: all four traces are scaled, ordered and moved such that they're lined up from top to bottom, all the same size. It would take forever to do manually and would just be a big pain in the butt.Sure, afterwards I might have to change the trigger source, type, params etc. but I'd have to do this anyway.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 11, 2014, 12:29:09 am
content: Quote from: John Coloccia on May 10, 2014, 11:03:33 amNoooo! Auto trigger is actually useful!Although if you're working on NORM, you can tap the FORCE TRIG a few times to get something up to date. Often easier than switching it to AUTO and tweaking an encoder. Not like flipping a switch and turning a pot on a '475.Tim

author: turbo!
author_rank: Regular Contributor
timestamp: May 11, 2014, 06:59:05 pm
content: Quote from: echen1024 on May 09, 2014, 02:12:56 amAnalog and digital each have their advantage. What you posted isn't a surprise at all. Digital equipment are much cheaper with hard goods than analog counter part.With a purchase of a set of encyclopedia, you're clearly paying a good amount for the intellectual property. A set of encyclopedias on high quality paper in full color costs thousands of times more than pressing a few DVDs. Physically, the DVD needs to be built to close enough tolerance to ensure readability and perform within acceptable vibration levels, but overwhelming portion of the cost goes to the contents. For instruments, a good portion of list price goes to dealer network as these instruments are sold through traditional business-to-business sales rep network who does everything including hand holding for end users.There are some parts that still require very close tolerance to actually work and can't be BS'd much, but for the most part, digital instruments can get away with roughening it in and BSing it using calibration constants. The materials used still need to be very stable in long term and critical components must have very low temperature coefficients, or have a very predictable coefficient.A high accuracy glass thermometer requires a very accurate bore diameter to maintain linearity. A cheap one would be marked at low, and high and marked evenly through out, but if the material is the same, then it is just as precise. 5C reading might mean 4.5C and 10C might mean 10.2C, but it is consistent. Inscribing the glass with lines where each line must corresponds to a very high level of accuracy is a costly process. If it was to use a scanner array like optical device to read the incision where the mercury is, it can be BSed numerically by simply comparing to a reference thermometer. So, reference thermometer and this thermometer is heated and cooled side by side until they both stabilize. If reference reads 28.0C, it marks that pixel location as 28.0C.You don't adjust the circuit. The digital processing reports the pixel location of where the mercury was seen and this pixel location is translated into value by multiplying it with a calibration constant.In analog circuits, proper true gain adjustments is important so that symmetric AC do not look asymmetrical.In analog driven digital meters, the analog circuits are adjusted to reflect proper reading on the digital display. In digital setup, you don't do anything with the circuit, but use calibration constants in EEPROM to absorb the slop.An analog scope literally have dozens and dozens of potentiometers and take many hours to adjust. However, with a service manual and sources, you can do it.A digital scope and automated calibration equipment talk to each other under the direction of program and quickly bust through the calibration routine. The ability to access almost every function available on front panel through the interface without touching the switch is more important for automatic production. If you need to service it later on, the constants in EEPROM are not self explanatory and you can't do anything about it and you're at the mercy of the manufacturer.

author: electronics man
author_rank: Frequent Contributor
timestamp: May 11, 2014, 07:36:22 pm
content: However I have seen new analog oscilloscopes for under £200 - significantly cheaper than digital ones

author: madshaman
author_rank: Frequent Contributor
timestamp: May 11, 2014, 09:25:20 pm
content: Since this is such a hot topic, I'm curious, how many of you would purchase an analog scope as good or near as good as a Tek 2465 if it were available new for the same price points as say Rigol's equipment at the same bandwidth?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 11, 2014, 09:50:25 pm
content: Last scope I got was a DSO, but mainly because I didn't have one already; next scope, I'll probably get something higher bandwidth, which probably won't be analog. After that... I would definitely consider a 2465 or something like that. If I didn't already have a 475, I think it would be a higher priority.Tim

author: G0HZU
author_rank: Super Contributor
timestamp: May 11, 2014, 10:21:22 pm
content: Quote from: madshaman on May 11, 2014, 09:25:20 pmEven though I do RF design for a living up to many GHz I'm not sure I can justify the need for an analogue scope with 400MHz BW. Most of the time (i.e. pretty much always) the added BW over 100MHz would be a source of irritation because of the higher noise. However, If someone produced an analogue scope that had 100MHz/20MHz switchable BW and it was small, light, efficient and didn't produce any fan noise and it was as nice to use as my old Tek 465 then I'd be interested in buying it to replace the 465. This is because the ideal analogue scope (for me) would be small, light and efficient and easy to move around. But I think that such a scope doesn't exist even 40+ years after the 465 was launched?

author: David Hess
author_rank: Super Contributor
timestamp: May 11, 2014, 10:56:58 pm
content: Besides the bandwidth advantage, higher bandwidth analog oscilloscopes also generally have a brighter and sharper CRT image giving them an advantage at low repetition rates even if you do not need the bandwidth.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 11, 2014, 11:34:50 pm
content: Every scope I've seen has a BW switch. Do they make 400MHz+ analog scopes without this? Why?

author: David Hess
author_rank: Super Contributor
timestamp: May 11, 2014, 11:58:22 pm
content: Quote from: T3sl4co1l on May 11, 2014, 11:34:50 pmThe Tektronix mainframe style oscilloscopes only had bandwidth limits on some of their plug-in amplifiers and none of them above 200 MHz. Oddly enough the common 100 MHz amplifier plug-ins lacked a bandwidth limit as well making the 200 MHz ones more useful even in a slower mainframe.

author: madshaman
author_rank: Frequent Contributor
timestamp: May 12, 2014, 12:37:58 am
content: I need a 20Mhz BW switch just to keep the local radio station off my traces and making them fat (when we move, there's going to be cheesy RF shielding, it'll be my own version of a tinfoil hat ^^).I'm thinking chicken-wire stretched in a web over the walls and ceiling in a double layer with a space between, all held at ground.

author: David Hess
author_rank: Super Contributor
timestamp: May 12, 2014, 01:09:31 am
content: I have the same problem with ambient EMI. The solution always ends up being better probes with shorter grounds or no probes at all.

author: madshaman
author_rank: Frequent Contributor
timestamp: May 12, 2014, 02:19:46 am
content: If I put the DUT inside an enclosure, I don't have a problem, the RF doesn't come through the probes.I second that at really high frequencies, lead length outside a transmission line doesn't help, because of the sudden change of impedance and obviously the uncompensated inductance. At least that's how I look at it. Being self taught, I'm not always sure if I've learned to look at things the same way or the correct way..

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 12, 2014, 02:33:42 am
content: Quote from: David Hess on May 11, 2014, 11:58:22 pmWell obviously, it still has a switch, it's just a lot bigger than mostyank this, shove that...Tim

author: electronics man
author_rank: Frequent Contributor
timestamp: May 12, 2014, 12:43:58 pm
content: Quote from: T3sl4co1l on May 12, 2014, 02:33:42 amNot tektronix but still interesting

author: electronics man
author_rank: Frequent Contributor
timestamp: May 13, 2014, 03:59:08 pm
content: the only reason i would buy an analog oscilloscope is for xy mode

author: madshaman
author_rank: Frequent Contributor
timestamp: May 13, 2014, 05:02:41 pm
content: Quote from: electronics man on May 13, 2014, 03:59:08 pmThere are plenty digital scopes with XY mode.

author: electronics man
author_rank: Frequent Contributor
timestamp: May 13, 2014, 05:51:11 pm
content: Quote from: madshaman on May 13, 2014, 05:02:41 pmI know, nearly all of them but they are not as good for xy mode as analog ones are

author: David Hess
author_rank: Super Contributor
timestamp: May 13, 2014, 06:09:02 pm
content: All of the DSOs I have seen operated in XY mode had pretty poor displays if only because of the way the record length interacts with the acquisition rate. A long record length is needed for a continuous display but that same long record length limits the acquisition rate making the display update slowly. Ideally the record length could be adjusted to be synchronous with the input signals but that defeats any easy use of XY mode and not all input signal are synchronous.One advantage DSOs do have though with XY displays is high X bandwidth. In an analog oscilloscope operating in XY mode, the vertical delay line introduces a phase error at low frequencies limiting performance to 10s of kHz. If that is compensated for which was a common option, then the relatively low horizontal bandwidth still limited performance to about 1 MHz. There were some expensive exceptions but the fastest I know of worked to 50 MHz.

author: David Hess
author_rank: Super Contributor
timestamp: May 13, 2014, 06:17:38 pm
content: Quote from: electronics man on May 13, 2014, 03:59:08 pmI bought an analog storage oscilloscope simply because it was a lot less expensive than the 4 channel 400 MHz DSO that could match its specifications. Then I bought two old DSOs for the same reason instead of a single modern 4 channel DSO. Between all of them I have more channels and more bandwidth at less cost than even a low end Rigol although I dismissed Rigol because of their misleading marketing.I acknowledge that that is not an avenue available to most people since they lack the experience to know what they need and the ability to maintain an old test instrument. It is pretty easy to be seduced by DSO features which are actually unimportant.

author: w2aew
author_rank: Super Contributor
timestamp: May 13, 2014, 08:47:31 pm
content: Analog scopes are still the best for monitoring RF transmitter output in applications like this:

author: Dave Turner
author_rank: Frequent Contributor
timestamp: May 15, 2014, 11:33:33 pm
content: Whilst rebuilding my lab after an absence of decades I've been severely limited by available space and budget. After discussion in this forum I chose a Rigol DS1074-Z which covers my needs.However had I more space and funds I would no doubt purchase an analogue scope.In whatever field one works in one should always learn the limitations of the tools at one's disposal and use the most appropriate for the job at hand. Even more important is to understand why and how they are used.Whilst useful &^%$£ auto can be counterproductive; use your head. It is, or should be, the most important instrument.

author: madshaman
author_rank: Frequent Contributor
timestamp: May 16, 2014, 05:34:24 pm
content: Quote from: Dave Turner on May 15, 2014, 11:33:33 pm+1Totally agree, in ANY field:Know your tools, know them well.Use the right tool for the right job.Don't have the right tool? Make it or buy it.It's so fundamental.

author: electronics man
author_rank: Frequent Contributor
timestamp: May 17, 2014, 10:29:35 am
content: But with limited funds a DSO gives you more bang for your buck

author: David Hess
author_rank: Super Contributor
timestamp: May 17, 2014, 11:16:10 am
content: Quote from: electronics man on May 17, 2014, 10:29:35 amIf used instruments are included then I disagree; a majority of applications do not require digital storage and some are better suited to an analog oscilloscope because of features they have which modern DSOs lack like dual sweep or continuous X-Y display. It is also possible to get more bandwidth for a given cost in the used analog oscilloscope market.

author: electronics man
author_rank: Frequent Contributor
timestamp: May 17, 2014, 11:18:54 am
content: Quote from: David Hess on May 17, 2014, 11:16:10 amI disagree most of the time I find my self stoping capture and looking at the data in the capture memory and you can't do that on a regular analog oscilloscope.

author: Lukas
author_rank: Frequent Contributor
timestamp: May 17, 2014, 11:22:59 am
content: Quote from: electronics man on May 17, 2014, 10:29:35 amI obtained a 400MHz analog storage Tektronix 7834 Oscilloscope for <100€ at a local hamfest. It also came with a 7A22 (10µV/div, 1MHz) plugin. No DSO comes even close.

author: electronics man
author_rank: Frequent Contributor
timestamp: May 17, 2014, 01:12:17 pm
content: Ok but there is still a lot a DSO can do that an analog scope can't. Analog scopes are for people who have very specific needs DSOs are more general purpose and much better for the hobbiest. What's ther aversion to DSOs all about?

author: Fsck
author_rank: Super Contributor
timestamp: May 17, 2014, 01:25:49 pm
content: Quote from: electronics man on May 17, 2014, 01:12:17 pmit's not an aversion. you're correct, DSOs can do many things analog scopes cannot. however, at the moment, an old (undoubtedly used) analog scope $ for $ is often superior to a new digital scope and cost is typically the major factor for hobbyists.the cheapest bang for buck DSO is currently what? the 1074z from Rigol I'm guessing with an entry price of >500$the best general purpose bang for buck analog scope is probably the 2465 series which can be acquired for 300-500$.to get a dso that is clearly superior to the 2465 series requires a fairly large jump in cost, however repair and maintenance will of course be a concern with old analog scopes.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 17, 2014, 01:46:55 pm
content: Quote from: electronics man on May 17, 2014, 01:12:17 pmIn my experience the reverse is the case.DSOs have promised much for many years,& only recently have they delivered on that promise.Earlier generations were very "clunky" in operation,so they were only appropriate for some work where their particular characteristics were useful.

author: electronics man
author_rank: Frequent Contributor
timestamp: May 17, 2014, 03:11:16 pm
content: Quote from: vk6zgo on May 17, 2014, 01:46:55 pmIt's not the case any more, I don't have much money so I wanted an oscilloscope that does as much as possible and that takes up as little room as possible and a device that doesn't limit what I can do very much so I went for a DSO, as my requirement meant I had to catch runt pulses and look at noise. You can't do either of these with a CRO

author: vk6zgo
author_rank: Super Contributor
timestamp: May 18, 2014, 03:14:21 am
content: Quote from: electronics man on May 17, 2014, 03:11:16 pm"Runt" pulses,no.but noise?------What do think we used before DSOs existed?And this wasn't just in a home Lab,but in Industry,where it had to work!Hypothetical:- You have a pulse train at around 15kHz PRF.High frequency components are up to 5MHz.You need to see if your signal has 50Hz hum on it.What does your display look like when you are set to around 5ms/div to show the hum?Many modern DSOs can do this,but some can't,as their sampling rate reduces,giving aliasing problems.None of the early generation DSOs could do it-----all CROs made since around 1947 can!

author: David Hess
author_rank: Super Contributor
timestamp: May 18, 2014, 03:51:51 am
content: Quote from: vk6zgo on May 18, 2014, 03:14:21 amWould you consider the 2230 or 2232 early generation? They could certainly do it but would be useless for quantifying noise unless a peak-to-peak measurement was acceptable but a lot of modern DSOs have the same limitation.

author: electronics man
author_rank: Frequent Contributor
timestamp: May 18, 2014, 09:52:22 am
content: Quote from: vk6zgo on May 18, 2014, 03:14:21 amOther high frequency noise? What about pass/ fail?

author: vk6zgo
author_rank: Super Contributor
timestamp: May 18, 2014, 10:35:16 am
content: Quote from: electronics man on May 18, 2014, 09:52:22 amOK.just pointing out that noise can be low frequency,too!High frequency noise is no problem.Pass/fail?--we were expected to be able to read p-p noise & check it against a specification,although therewerepass/fail graticules for noise.If the noise signal is substantially sinusoidal,a good estimate can also be made of its RMS value.If it is fairly close to white noise,a substitution method can get a fairly accurate result.DSOs are very useful for repetitive testing,but such tests were done with analog 'scopes for many years.