EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: T@ller on December 22, 2016, 02:36:34 pm
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Hello everyone.
I would like to acquire oscilloscope for my home experiments\hobby. Need advice which one\type will be better.
So. Usually I work with "digital" signals (square wave signal). "Analog" - rarely. The highest frequency that I ever faced - 50-60 Mhz. I don't need high precise because usually I just want to see what is going on in some point in electronic board.
I have started looking around price 100$. Have a low budget for "toy".
In this price I found several models analog and digital scopes that I guess could be interested.
Analog:
Tektronix 2225(50MHz),2235(100MHz).
Ez Digital OS-5060(60MHZ).
Digital:
USB Hantek\Intrustar 60-70MHz bandwith.
I have experience with analog scopes but not digital. Actually I prefer analog scope but In the other hand - analog scopes that I listed is very old. May be better not waste time and buy USB digital ?
Thanks.
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If you go USB try to find used or discounted PicoScope. It has turned out they have skipped some shortcuts that can be found in some low-end scopes:
https://www.eevblog.com/forum/testgear/testing-dso-auto-measurements-accuracy-across-timebases/ (https://www.eevblog.com/forum/testgear/testing-dso-auto-measurements-accuracy-across-timebases/)
If you decide to go for new non-Pico USB - try to find a a way to test it according to same procedure and post the test to benefit others also. If it does not pass the test you will mis out on lot of stuff that can be done on DSO, compared to basic CRO. For example looking at 2 waves with wildly different frequencies and get accurate automated stats on both. Or just looking at one wave with precise freq but long period.
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This current thread should help you as it covers the same question and price band... ;)
https://www.eevblog.com/forum/beginners/best-oscilloscope-under-$100-cad/ (https://www.eevblog.com/forum/beginners/best-oscilloscope-under-$100-cad/)
You may have a bit more budget depending on which $
EDIT: Link corrected, thank you nctnico!
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This current thread should help you as it covers the same question and price band... ;)
https://www.eevblog.com/forum/beginners/best-oscilloscope-under- (https://www.eevblog.com/forum/beginners/best-oscilloscope-under-)$100-cad/
You may have a bit more budget depending on which $
EDIT: Sorry, can't get the link to work because it contains a $ symbol... Unless someone is cleverer than me can do it. Look in the Beginners section for "best-oscilloscope-under-$100-cad"
FFS: use the 'insert hyperlink' button! |O
https://www.eevblog.com/forum/beginners/best-oscilloscope-under-$100-cad/ (https://www.eevblog.com/forum/beginners/best-oscilloscope-under-$100-cad/)
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Thank you nctnico, at least I know now! >:(
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The Tektronix 2225 and 2235 are good choices for a limited budget however I do not recommend an oscilloscope that old unless you are confident in your ability to repair and maintain it or have a friend who can help you out.
If you are considering a 2235, then also look for a 2230 or 2232 and if a single timebase is acceptable, also the 2221 and 2221A. They are all based on the 2235 but can operate as digital storage oscilloscope and can sometimes be found for about the same price. Their extra complexity however makes the warning above about being prepared to repair and maintain them even more important.
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+1 on David Hess suggestion on old scope. :-+
Tons of this so called "expert" advises sometimes never consider the OP have to deal with a broken "OLD" scope and with high probability that it can not be fixed.
If budget allowed, DO NOT buy old/used scope without warranty if you don't have enough skill/knowledge ... AND ... adequate tools, which sometimes need ANOTHER WORKING SCOPE to fix it.
Hell, even you have the time, energy, knowledge, skills and tools, still there is NO guarantee that you can fix it, if the broken part is an unobtainium chip. :palm:
The appetite for old exotic analog scope is only makes sense, if you already have a working scope, and it will be the 2nd scope.
Why risk it ? :-// A toy scope is still much-much better than an exotic GHz analog scope, but broken.
My 2 resistors worth.
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"Digital debugging" consists of primarily three activities. Firstly making sure that the analogue signal (because all signals above femtoamp level are analogue signals) will be correctly interpreted by the receiver as a digital signal - i.e. ensuring "signal integrity". Secondly, once you have valid digital signals, you often need to see the precise relationship between them, especially ensuring setup and hold times are correct. Finally, sometimes you need interpret the digital signals, e.g. to determine a count or a FSM state or the contents of a serial message.
Signal integrity requires bandwidth above all else, coupled with good probing technique. 100MHz is barely adequate for modern logic.
Timing relationship also requires bandwidth, but also requires >=2 input channels (2 is often sufficient).
Interpretation is frequently best done with digital tools, not oscilloscopes. Logic analysers for wide busses, "Bus Pirate" for many common protocols, and even printf() statements.
The single area where digital storage scopes have a USP is for slow and single-shot events.
My preference is: a working old scope with >250MHz bandwidth, plus a Digilent Analog Discovery for slow single-shot slow events (also has a waveform generator, logic generator, logic analyser), plus printf() statements. To that must be added imagination, understanding, and a disciplined approach to design and debugging :)
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If budget allowed, DO NOT buy old/used scope without warranty if you don't have enough skill/knowledge ... AND ... adequate tools, which sometimes need ANOTHER WORKING SCOPE to fix it.
Hell, even you have the time, energy, knowledge, skills and tools, still there is NO guarantee that you can fix it, if the broken part is an unobtainium chip. :palm:
The appetite for old exotic analog scope is only makes sense, if you already have a working scope, and it will be the 2nd scope.
I agree completely with tggzzz. Signal integrity and timing can almost always be handled by an analog oscilloscope and bandwidth is more important than digital storage or extra features. I think 200 MHz is ideal because probing becomes difficult above that but I do almost all my work with a 100 MHz oscilloscope. Decoding can be done on an analog oscilloscope under certain conditions as well with a little bit of extra work; setup the pattern to be decoded so it repeats. The one common exception would be detecting rare events like metastability and some timing violations.
A known working analog oscilloscope like one of the ones I discussed is a pretty low risk but how would anybody who lacks experience confidently know how to verify that they are operating correctly? And what if you cannot inspect the oscilloscope before purchasing which will be common with online sales?
The first DSO that I bought for myself was a 2230 for $80 (1) but I already had a couple of other analog oscilloscopes I could use to repair it if necessary and a lot of electronics experience. Actually, I bought two 2230s with one for $80 and another for $60 thinking that between the two of them, I could get one working. As it ended up, one worked fine and the other was repairable although it took more than a month to track down the exact problem. Between the two, I effectively have a 4 channel 100 MHz DSO with separate dual delayed timebases which comes in very handy sometimes.
I get a lot of use out of my slow CRT digital storage oscilloscopes for low repetition rate things like power supply startup and shutdown. It is very rare than I need "real time" sampling sufficient for a 100 MHz bandwidth or higher; I would rather have equivalent time sampling at 2 GS/s for accurate transient response.
(1) At the time, I evaluated the Rigol DS1000D and DS1000E series and after talking with their customer support, concluded that they make toys. I still think that is the case.
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I agree with the statements I've snipped.
I get a lot of use out of my slow CRT digital storage oscilloscopes for low repetition rate things like power supply startup and shutdown.
Yes :( I had a PSU startup problem where I could do one test every 6 hours. The problem was in the startup components, and once started they would work for the next 6 hours!
It is very rare than I need "real time" sampling sufficient for a 100 MHz bandwidth or higher; I would rather have equivalent time sampling at 2 GS/s for accurate transient response.
Yes again. I haven't heard a significant number of use cases on this forum for "high" bandwidth RTS, but ETS is very useful.
The only addition I will make to my statement about the Digilent Analog Discovery is that the combination of AWG, scope and post processing gives the ability to plot phase-frequency response diagrams in various forms; great for filter/amplifier analysis and control-loop analysis. The abiility to script tests and measurements adds the potential for automating repetitive tasks.
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Don't buy old osciloscopes, is the path for pain, All new low bandwitch < 100Mhz are better than old ones, even the chinese ones, Old scopes can be a deal only on the > 500Mhz specs, but Old means OLD you get what you paid for. If you are a begginer it's high recomended to start with a cheap new scope like hanteck, picoscope, owon usb or even better rigold DS1054z with 4 chanelss
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Thanks to all.
I would prefer working with old analog scope. But considering all specific things - buying new digital simple oscilloscope will be more reasonable. :-\
Now I dont see any interesting old analog scope on ebay.
For example Tek 2235 and in state "AS IS" can costs up to 200$. Tek 2225 up to 150$.
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Now I dont see any interesting old analog scope on ebay.
For example Tek 2235 and in state "AS IS" can costs up to 200$. Tek 2225 up to 150$.
Those in the US have a much easier time finding old analog oscilloscopes in good condition for low prices. The difficulty of doing this in Europe and probably even more so in eastern Europe make a new even if low quality Chinese DSO more desirable. You have to cut the coat to fit the cloth.
Even so, I watched Ebay for a couple of months making notes of what models sold for how much before picking up my 2230s for less than $100 each.
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If you want old things here they are
http://www.ebay.com/itm/TEKTRONIX-TAS-250-TWO-CHANNEL-DIGITAL-ANALOG-50MHz-PORTABLE-OSCILLOSCOPE-PARTS/361853164626?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D38530%26meid%3Dd36cbf92141c4a2cbedc2592873f3f01%26pid%3D100005%26rk%3D6%26rkt%3D6%26sd%3D182395065396 (http://www.ebay.com/itm/TEKTRONIX-TAS-250-TWO-CHANNEL-DIGITAL-ANALOG-50MHz-PORTABLE-OSCILLOSCOPE-PARTS/361853164626?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D38530%26meid%3Dd36cbf92141c4a2cbedc2592873f3f01%26pid%3D100005%26rk%3D6%26rkt%3D6%26sd%3D182395065396)
(http://i.ebayimg.com/images/g/oQEAAOSwiONYQbUw/s-l1600.jpg)
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If you want old things here they are
http://www.ebay.com/itm/TEKTRONIX-TAS-250-TWO-CHANNEL-DIGITAL-ANALOG-50MHz-PORTABLE-OSCILLOSCOPE-PARTS/361853164626?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D38530%26meid%3Dd36cbf92141c4a2cbedc2592873f3f01%26pid%3D100005%26rk%3D6%26rkt%3D6%26sd%3D182395065396 (http://www.ebay.com/itm/TEKTRONIX-TAS-250-TWO-CHANNEL-DIGITAL-ANALOG-50MHz-PORTABLE-OSCILLOSCOPE-PARTS/361853164626?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D38530%26meid%3Dd36cbf92141c4a2cbedc2592873f3f01%26pid%3D100005%26rk%3D6%26rkt%3D6%26sd%3D182395065396)
Thanks. I did not pay attention for that scopes. Is it more reliable than 2225\35 ?
As far as I understood this scope does not work and lost two knobs. ???
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How about this one ?
http://www.ebay.com/itm/EZ-OS-5060A-60MHz-Analog-oscilloscope-RK-/152366029354?hash=item2379b91a2a:g:UrUAAOSwux5YUr0p (http://www.ebay.com/itm/EZ-OS-5060A-60MHz-Analog-oscilloscope-RK-/152366029354?hash=item2379b91a2a:g:UrUAAOSwux5YUr0p)
(http://i.ebayimg.com/images/g/UrUAAOSwux5YUr0p/s-l500.jpg)
Or this ?
http://www.ebay.com/itm/GW-INSTEK-Oscilloscope-GOS-6112-100MHz-GOS-6112-Great-Used-Cond-No-cords-Lead-/142219234987?hash=item211ced4eab:g:MHQAAOSwo4pYWeP7 (http://www.ebay.com/itm/GW-INSTEK-Oscilloscope-GOS-6112-100MHz-GOS-6112-Great-Used-Cond-No-cords-Lead-/142219234987?hash=item211ced4eab:g:MHQAAOSwo4pYWeP7)
(http://i.ebayimg.com/images/g/qYgAAOSwJ7RYWeQr/s-l500.jpg)
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Well it's not a Tek so probably won't be the same build quality. At 60MHz it shouldn't use any custom silicon. It Looks as if EZ-Digital is a Korean brand.
Specs are here: http://www.jameco.com/Jameco/Products/ProdDS/2145271.pdf (http://www.jameco.com/Jameco/Products/ProdDS/2145271.pdf)
An important factor is whether you can find a service manual.
You would also need to factor in the cost of a pair of scope probes.
EDIT: Missing button caps on Channel 2.
EDIT1: Manual, but only includes block diagram: http://www.jameco.com/Jameco/Products/ProdDS/2145262%20UsersManual.pdf (http://www.jameco.com/Jameco/Products/ProdDS/2145262%20UsersManual.pdf)
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Gyro
Yes, I agree Tek is maybe better
About probes - not a problem here. Of cource in case that any probes with BNC connector are compatible.
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(I added the manual link for the EZ scope to my last reply, it only includes an unreadable block diagram, no service info)
The Instek one you added has higher bandwidth (100MHz vs 60MHz) higher sensitivity max (2mV vs 5mV/div) Input limit is also 400V vs 250V (though that shouldn't be an issue if you are using your x10 scope probes correctly!).
The Instek also has readouts and lists SMD technology as one of it's benefits (It will have some digital stuff inside). Both could either be a benefit or issue if you need to fix it! The seller seems to have several of these, I don't know whether that gives a higher chance of a fully working one. :-\
In other things they both appear to have what you would expect in an analogue scope, dual timebase, A+B with Ch2 invert for differential measurement, Z mod. etc.
Here's a link to the GW Instek specs: http://www.test.it/sitonew/Specifiche%20strumenti/INSTEK/GOS-6112-6103-6103C.pdf (http://www.test.it/sitonew/Specifiche%20strumenti/INSTEK/GOS-6112-6103-6103C.pdf). Given the added complexity it's probably more important that you locate a service manual for this one.
None of this helps with your fundamental Analogue vs Digital question of course!
EDIT: Manual link - only block diagram again! http://www.stantronic.co.uk/GOS-6112.html (http://www.stantronic.co.uk/GOS-6112.html)
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The Instek one you added has higher bandwidth (100MHz vs 60MHz) higher sensitivity max (2mV vs 5mV/div) Input limit is also 400V vs 250V (though that shouldn't be an issue if you are using your x10 scope probes correctly!).
The Instek also has readouts and lists SMD technology as one of it's benefits (It will have some digital stuff inside). Both could either be a benefit or issue if you need to fix it! The seller seems to have several of these, I don't know whether that gives a higher chance of a fully working one. :-\
I suspect the gos-6112 came from the ITT Tech auction a couple weeks ago. They had many hundreds of these available. I ended up with a few myself and will say everything I won at this auction was in full working order. If you are interested in the Instek you may want to wait a bit. I know many of these scopes sold for as little as $1 and a better price is likely to come along.
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Thanks. I did not pay attention for that scopes. Is it more reliable than 2225\35 ?
As far as I understood this scope does not work and lost two knobs. ???
The description says it is missing the variable knobs and the photo does show that. I would be more worried about the oscilloscope's questionable history than the missing variable knobs.
The TAS series are newer than the 22xx and 24xx series and they are suppose to be designed for reliability but they are also more difficult to repair if there is a problem if only because their service documentation is not as complete.
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Input limit is also 400V vs 250V (though that shouldn't be an issue if you are using your x10 scope probes correctly!).
Be very careful about using x10 probes to divide an input signal down to within the overload range of the oscilloscope. Since they rely on the oscilloscope's 1 megohm input resistance, if the oscilloscope coupling is set to AC, the DC level will be applied to the oscilloscope input without attenuation. This is a more common problem with x100 probes.
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Hmm... could you explain that a little more, please? Seems like an important topic to understand...
Tek 2215a input circuitry, for reference:
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I suspect the gos-6112 came from the ITT Tech auction a couple weeks ago. They had many hundreds of these available...
Interesting information. There is one auction . :)
Look:
http://www.ebay.com/itm/LOT-60-GW-Instek-GOS-6112-2-Channel-100MHz-Curser-Readout-Analog-Oscilloscope-NR-/152363765934?hash=item23799690ae:g:5agAAOSwImRYWY8- (http://www.ebay.com/itm/LOT-60-GW-Instek-GOS-6112-2-Channel-100MHz-Curser-Readout-Analog-Oscilloscope-NR-/152363765934?hash=item23799690ae:g:5agAAOSwImRYWY8-)
(http://i.ebayimg.com/images/g/5agAAOSwImRYWY8-/s-l500.jpg)
By the way. Also there is several listings for digital scope "GW INSTEK GDS-2102 Oscilloscope 2 Analogue 100 MHz 1 GSPS 25 kpts 3.5 ns" - quite interesting.
http://www.ebay.com/itm/GW-INSTEK-GDS-2102-Oscilloscope-2-Analogue-100-MHz-1-GSPS-25-kpts-3-5-ns-/201758279449?hash=item2ef9bb0719:g:h1IAAOSw241YXFu8 (http://www.ebay.com/itm/GW-INSTEK-GDS-2102-Oscilloscope-2-Analogue-100-MHz-1-GSPS-25-kpts-3-5-ns-/201758279449?hash=item2ef9bb0719:g:h1IAAOSw241YXFu8)
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Those GW-Instek oscilloscopes from ITT Tech do look like a good deal except for lack of service documentation. Of course even with service documentation, their surface mount construction could make maintenance difficult.
Hmm... could you explain that a little more, please? Seems like an important topic to understand...
Tek 2215a input circuitry, for reference:
The Tektronix 2215A illustrates the problem perfectly and is typical for a good design.
A standard x10 probe is just a 9 megohm series resistor with a controlled parallel capacitance so the AC and DC division ratios are the same. The parrallel input capacitance and 1 megohm input resistance to ground inside the oscilloscope makes up the second part of the divider.
When the oscilloscope input is set to DC coupling, both DC and AC signals are attenuated to 1/10th of their normal value. But when the oscilloscope input is set to AC coupling which places a capacitor in series with the input, C2 in this case, then the shunt 1 megohm resistor inside the oscilloscope, R3 + R5 in this case, is no longer connected across the input at DC and the coupling capacitor is free to charge to the DC value of the signal through the probe's 9 megohm series resistance *without being attenuated*! So the probe is no longer attenuating the DC level.
With x10 probes this is usually not a problem because the oscilloscope input and probe input will have the same high voltage rating and users always operate their equipment within the specified bounds. Yea, right. But it can be a serious issue with standard x100 probes which will be rated to 1.2 kilovolts or higher. Setting the oscilloscope input to AC coupling with 1.2 kilovolts applies to a x100 probe will almost certainly cause the input AC coupling capacitor to break down risking damage to the oscilloscope input circuits.
Some x100 and a very few x10 probes include internal shunt resistors to prevent this problem.
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Those GW-Instek oscilloscopes from ITT Tech do look like a good deal except for lack of service documentation. Of course even with service documentation, their surface mount construction could make maintenance difficult.
IMHO service documentation is very much overrated. Tektronix and HP machines usually have a few custom chips or EPROMs which can go bad so even with service documentation you are left with a unit which needs an extra (self designed) board to become operational again. For a modern EE SMT components should not be a problem. Also most equipment works using publicly known methods so with some ingenuity you can identify the function of a component (or group of components) and go from there. I've repaired lots of equipment without schematics.
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Those GW-Instek oscilloscopes from ITT Tech do look like a good deal except for lack of service documentation. Of course even with service documentation, their surface mount construction could make maintenance difficult.
IMHO service documentation is very much overrated. Tektronix and HP machines usually have a few custom chips or EPROMs which can go bad so even with service documentation you are left with a unit which needs an extra (self designed) board to become operational again. For a modern EE SMT components should not be a problem. Also most equipment works using publicly known methods so with some ingenuity you can identify the function of a component (or group of components) and go from there. I've repaired lots of equipment without schematics.
The most likely problems involve power supplies, sensitive inputs, and mechanical parts rather than custom semiconductor and passive parts which are likely to be integrated circuits and hybrids which have higher reliability.
I have repaired lots of equipment without service documentation but I did not like it and it was always easier to do with service documentation.
For an experienced electronics technician or electronics engineer, I would recommend a well documented Tektronix 465B or later oscilloscope instead of a newer but undocumented alternative unless the later was very inexpensive. As it ends up though, there is some pretty good service documentation for the GOS-6112 available online.
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Guys.
Look on this Tek 2246:
http://www.ebay.com/itm/Tektronix-2246-100-MHz-4-Channel-Oscilloscope-POWER-TESTED-/322370820559?hash=item4b0ecc59cf:g:ffcAAOSwmLlX9VM7 (http://www.ebay.com/itm/Tektronix-2246-100-MHz-4-Channel-Oscilloscope-POWER-TESTED-/322370820559?hash=item4b0ecc59cf:g:ffcAAOSwmLlX9VM7)
(http://i.ebayimg.com/images/g/ffcAAOSwmLlX9VM7/s-l500.jpg)
I am not so interested in 4ch scope and it is big enough. But price is low and may be scope will work, at least 1-2 channels.
:)
Or may be Tek 2213A:
http://www.ebay.com/itm/Tektronix-2213A-Analog-Oscilloscope-/201762605727?hash=item2ef9fd0a9f:g:xMAAAOSw-0xYYY15#rwid (http://www.ebay.com/itm/Tektronix-2213A-Analog-Oscilloscope-/201762605727?hash=item2ef9fd0a9f:g:xMAAAOSw-0xYYY15#rwid)
I heard that 2213A had a problem with CRT tube.
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Look on this Tek 2246:
http://www.ebay.com/itm/Tektronix-2246-100-MHz-4-Channel-Oscilloscope-POWER-TESTED-/322370820559?hash=item4b0ecc59cf:g:ffcAAOSwmLlX9VM7 (http://www.ebay.com/itm/Tektronix-2246-100-MHz-4-Channel-Oscilloscope-POWER-TESTED-/322370820559?hash=item4b0ecc59cf:g:ffcAAOSwmLlX9VM7)
How much is shipping to Ukraine? To Spain it's $96
$156 for that? Nope.
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Look on this Tek 2246:
...
I am not so interested in 4ch scope and it is big enough. But price is low and may be scope will work, at least 1-2 channels.
I have a 2246 and a 2247A and they are excellent and reliable oscilloscopes. We hear about very few problems with them over on the TekScopes@yahoogroups.com email list. They are also generally newer than the 2225 and 2235 series so suffer from fewer age related problems.
While these are 4 channel oscilloscopes, not all channels are equal. They really have 2 main channels and 2 auxiliary channels which primarily serve as external trigger inputs that happen to have position controls and 0.1V/div and 0.5V/div sensitivity settings. The auxiliary channels work great for viewing logic signals.
Or may be Tek 2213A:
...
I heard that 2213A had a problem with CRT tube.
It was the 2213 and 2215 which had CRT problems; the original designs had too high of a heater voltage causing short CRT life. For that and other reasons, I never recommend the 2213 and 2215 although they can be fine oscilloscopes.
The 2213A and 2215A are cost reduced lower bandwidth versions of the 2235 and came out one year after the 2235 to replace the older 2213 and 2215 designs.
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@ David Hess
Just quickly I'd appreciate your comments on the 2465, got my eye on one. ;)
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@ David Hess
Just quickly I'd appreciate your comments on the 2465, got my eye on one. ;)
I only recently got a rebuilt 2445B recently so I am hardly an expert on the 2465 series beyond what I have read and discussed on the TekScopes@yahoogroups.com email list. They are fabulous oscilloscopes but suffer from more problems than the 4 channel 22xx oscilloscopes and have some special issues:
1. The vertical, horizontal, and z-axis DIP hybrids in these oscilloscopes are not as reliable as they should be and if they fail, the only likely replacements are from donor oscilloscopes.
2. Calibration is not trivial and the calibration data is stored in non-volatile memory. This data will be lost if the lithium battery runs dead or the EAROM fails. This may not be a problem if you do not require high accuracy.
3. Some units have surface mount aluminum electrolytic capacitors which need to be replaced before they leak and damage the printed circuit boards.
If my 2445B had the optional universal timer/counter, then I would use it in place of my 2247A.
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@ David Hess
Just quickly I'd appreciate your comments on the 2465, got my eye on one. ;)
I only recently got a rebuilt 2445B so I am hardly an expert on the 2465 series beyond what I read on the TekScopes@yahoogroups.com email list. They are fabulous oscilloscopes but suffer from more problems than the 4 channel 22xx oscilloscopes and have some special issues:
1. The vertical, horizontal, and z-axis DIP hybrids in these oscilloscopes are not as reliable as they should be and if they fail, the only likely replacements are from donor oscilloscopes.
2. Calibration is not trivial and the calibration data is stored in non-volatile memory. This data will be lost if the lithium battery runs dead or the EAROM fails. This may not be a problem if you do not require high accuracy.
3. Some units have surface mount aluminum electrolytic capacitors which need to be replaced before they leak and damage the printed circuit boards.
I have a 2465 and a 2445B. Both had mains suppression capacitors that needed to be replaced (some had cracked); I would expect most scopes to have that syndrome too. They are easy to replace, but it is preferable to do it before they short circuit and a series resistor disappears. Ensure you get the right X/Y ratings. FFI see http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf (http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf)
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1. The vertical, horizontal, and z-axis DIP hybrids in these oscilloscopes are not as reliable as they should be and if they fail, the only likely replacements are from donor oscilloscopes.
Sphere have some of them but they're not cheap. :scared:
2. Calibration is not trivial and the calibration data is stored in non-volatile memory. This data will be lost if the lithium battery runs dead or the EAROM fails. This may not be a problem if you do not require high accuracy.
It looks like it's booting OK at present, it shows a raster on the sellers imagery. Would it pass the boot self tests and go on to display a raster if the ROM had failed ?
3. Some units have surface mount aluminum electrolytic capacitors which need to be replaced before they leak and damage the printed circuit boards.
IIRC the problem units can be identified by SN #'s ?
This one's B025093. IIRC the Tek plant can be identified by this too ?
It looks a clean unit with a front cover and hard copy SM too. :-+
No Tek probes though. :'( :--
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I have a 2465 and a 2445B. Both had mains suppression capacitors that needed to be replaced (some had cracked); I would expect most scopes to have that syndrome too. They are easy to replace, but it is preferable to do it before they short circuit and a series resistor disappears. Ensure you get the right X/Y ratings. FFI see http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf (http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf)
Thanks tgg, yeah been there done that on X and Y rated timebombs. ::)
Scope like these don't come up very often here..........not that really need it but it does seem fairly priced for a 300 MHz 4 ch scope. Like all these better Tek 2xxx scopes the hybrids and the state of the fan is of primary concern when getting a used one. They have a boot and hour counter don't they ?
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1. The vertical, horizontal, and z-axis DIP hybrids in these oscilloscopes are not as reliable as they should be and if they fail, the only likely replacements are from donor oscilloscopes.
Sphere have some of them but they're not cheap. :scared:
QService also sells them directly and on ebay; some fail more often and are therefore more expensive. I've had zero problems with QService[1]
2. Calibration is not trivial and the calibration data is stored in non-volatile memory. This data will be lost if the lithium battery runs dead or the EAROM fails. This may not be a problem if you do not require high accuracy.
It looks like it's booting OK at present, it shows a raster on the sellers imagery. Would it pass the boot self tests and go on to display a raster if the ROM had failed ?
If the calibration EAROM or battery+RAM is corrupt, it will boot and display a self-test error. When I sell my 2445B I will show a picture indicating that all the self-tests have passed. I am not aware of a way of finding how near the battery is to failing.
3. Some units have surface mount aluminum electrolytic capacitors which need to be replaced before they leak and damage the printed circuit boards.
IIRC the problem units can be identified by SN #'s ?
This one's B025093. IIRC the Tek plant can be identified by this too ?
I suspect that the control boards for 24x5 are EAROM and PTH, but 24x5B are SMD and Dallas battery backed RAM. If it mattered, that can be determined from the online free scanned manuals.
[1] unlike an Israeli company p...... where I waited 6 weeks, and they didn't suggest sending one of the others they were advertising as being available. I raised a issue with ebay, the seller issued a refund - and a few days later they told me the shipper had returned the shipment to them, and did I still want it! Hmmm. (By that time I had received one from QService)
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How much is shipping to Ukraine? To Spain it's $96
$156 for that? Nope.
Well. It costs 6$ per each Kg in US->UA direction.
Internal delivery, to shipping company US address, usually costs about 20$. For DSO a bit less.
For example: shipping weight, external delivery costs, total delivery costs:
TEK 2246 - near 12kg - 72$ - 92$
TEK 2225,2235 - 9kg - 54$ - 74$
TEK 2213A - 7kg - 42$ - 62$
DSO Instek GDS-2102 - 4.3kg - 25.8$ - near 45$
DSO Rigol 1102 - 3.5kg - 21$ - near 40 $
To tell the truth TEK 2246 is weight too much. I am not shure...
What I have to say. I expected spending for delivery US->UA about 40-50$.
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How much is shipping to Ukraine? To Spain it's $96
What I have to say. I expected spending for delivery US->UA about 40-50$.
On eBay the chipping costs are decided by the seller.
They also have to pack it, take it to the post office, etc.
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2. Calibration is not trivial and the calibration data is stored in non-volatile memory. This data will be lost if the lithium battery runs dead or the EAROM fails. This may not be a problem if you do not require high accuracy.
It looks like it's booting OK at present, it shows a raster on the sellers imagery. Would it pass the boot self tests and go on to display a raster if the ROM had failed ?
The power on self test will reveal the problem and I think the readout will also draw a bunch of horizontal dots at the bottom of the display if the calibration data is corrupted or missing.
3. Some units have surface mount aluminum electrolytic capacitors which need to be replaced before they leak and damage the printed circuit boards.
IIRC the problem units can be identified by SN #'s ?
This one's B025093. IIRC the Tek plant can be identified by this too ?
It looks a clean unit with a front cover and hard copy SM too. :-+
No Tek probes though. :'( :--
I think the first series, 2445 and 2465, were all through hole so do not suffer from the surface mount aluminum electrolytic problem. These also use an EAROM which is sort of like an EEPROM for the calibration data.
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Thanks for your help David and tgg
On the one i've had my eye on the readout looks a bit fuzzy (not sharp) but the trace OK, I've spotted threads and posts about how to fix the readout clarity.........still studying.
Meanwhile I've been getting up to speed on 2465's in BravoV's great thread where it seems my fellow Siglent distributor rf-loop has had a lot of experience with 2465's.
https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/ (https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/)
Anyway while I've been pissing around someone's grabbed it and I've missed out, bugger. :rant:
http://www.trademe.co.nz/Browse/Listing.aspx?id=1230265572 (http://www.trademe.co.nz/Browse/Listing.aspx?id=1230265572)
Anyway I probably didn't need another scope to add to the boxes of them I have. :-DD
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While I am making decision the 2213A was sold >:(
David Hess
Thanks for explanation about Tek scopes evolution. Useful. :-+
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Anyway while I've been pissing around someone's grabbed it and I've missed out, bugger. :rant:
While I am making decision the 2213A was sold >:(
At last count, this thread had 1032 views. Unfortunately it's on of the downsides these days. :(
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While I am making decision the 2213A was sold >:(
Double shot. 5 x Tek 2246 was sold too... :)
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I have repaired a lot of oscilloscopes and I have a collection of analog oscilloscopes.
Here are some personal considerations on this subject.
The main advantage of the analog oscilloscope is its simplicity.
At one time, it was sought to sophisticate it and to make it perform functions for which it was not originally conceived as measures of tensions and time with high precision.
These are the analog oscilloscopes with cursors.
We also wanted to combine the advantages of the analog oscilloscope and digital, which produced "ugly little lame ducks" called combiscopes.
Do not waste your time and money with these lame hybrids.
If you want the storage function or if you want to make accurate measurements, buy a digital oscilloscope, there is no match.
The analog oscilloscope is still very useful in various fields, in repair, in low precision measurements on complex periodic analog signals.
What should you buy?
A single oscilloscope, 2 channels, 50Mhz or more.
What are my preferences?
1) Tektronix: 465B or 2235
2) Hameg HM605 or HM1005 (NB: no component tester)
3) HP: 1740A
4) Philips: I do not like very much the Philips oscilloscopes.
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Sound points, oldway.
Having 465, 475A+DM44, 485, 2445B, 2465, HP1740A, and an Analog Discovery, my preferences would be:
- 485 for digital signal integrity and general purpose use
- Analog Discovery as a storage scope and network/spectrum analyser, with a basic AWG, pattern generator and logic analyser thrown in
If I had to get rid of the 485, then my preference would be the 2465, the 475A and the hp1740a, in that order (due to their bandwidth).
But I have a soft spot for the HP1740A - it is a pleasure to use and easy to disassemble (unlike the 465, 475A, and the calibration RAM in the 24x5Bs)
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I'd get a Tektronix TDS500 or TDS700 series before thinking about getting an even older analog scope. Lots of knowledge and parts available to fix them.
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oldway
Thanks for advice. And to other guys too.
Models which I guess will be good for general purpose and with 50+Mhz bandwith - for me :
Tek 2213A,2215A
Tek 2235
Tek 2225 - interesting model, why it appeared if there were 2213A,2215A in the same specs ?
HP\Agilent 546xxx - quite specific scope, but a bit smaller and in the same price up to 100$
That is all.
Rigol, Instek costs up to 200$
Tek TDS - as I understood is not my choice.
And I dont understand why Tek 4XX so popular. It is older and much heavier.
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And I dont understand why Tek 4XX so popular. It is older and much heavier.
Heavier, but not much heavier. The 465/475 was designed to fit under aircraft seats.
Why are they still popular? Partly because at the time the 465/475/485 were the best scope in that class, so everybody had them and used them, and now has fond memories of them.
Provided they are functional, they continue to work very well and are a delight to use; you don't get any unpleasant surprises. That's not true for many many scopes; in that sense 465/475/485 are an improvement on many of their successors!
When they need repairing, they are relatively easy to repair: the manuals are good, there is a ready supply of spare parts, and many people are happy to pass on hints and tips.
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Models which I guess will be good for general purpose and with 50+Mhz bandwith - for me :
Tek 2213A,2215A
Tek 2235
Tek 2225 - interesting model, why it appeared if there were 2213A,2215A in the same specs ?
There are 3 major series of 2 channel 22xx oscilloscopes:
- 2213 and 2215 - 30pF inputs, 60 MHz maximum. The early power supply for this series was problematical. The modified power supply is almost identical to the 2235 series power supply.
- 2235 - 20pF inputs, 100 MHz maximum, improved switching power supply, many models including 2213A, 2215A, 2230, 2232, and 2236. These replaced the 2213 and 2215.
- 2225 - 25pF inputs, 50 MHz maximum, line frequency transformer isolated switching power supply, 500uV/div sensitivity, single sweep only with no delay.
And I dont understand why Tek 4XX so popular. It is older and much heavier.
Except for the 485, they are easier to maintain because they use linear instead of switching power supplies.
The 454, 454A, 475, 475A, and 485 have higher bandwidth than any of the 22xx oscilloscopes. The 475, 475A, and 485 may have a brighter and sharper CRT than the 22xx oscilloscopes.
The oldest in this series, the 453, 453A, 454, and 454A have no custom ICs or hybrids.
The 465B and 485 have alternate dual delayed sweep. Most of the other 4xx oscilloscopes have mixed sweep which is not as useful.
The 50 MHz 455 and 100 MHz 465M are ruggedized models which use an easier to maintain internal arrangement. Unfortunately they have mixed sweep instead of alternate sweep.
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David, thanks for the insights. :-+
The 475, 475A, and 485 may have a brighter and sharper CRT than the 22xx oscilloscopes.
Why is that ? Better or different crt ?
The 465B and 485 have alternate dual delayed sweep. Most of the other 4xx oscilloscopes have mixed sweep which is not as useful.
So in 4xx series, these two are considered to be top models ?
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It is not easy to compare CRT's about sharpness and brightness because you are limited by the risk of burning the phosphor and there is no way to measure it.
Then, it is a bit subjective.
But I think the best CRT I know is the one of my Hameg HM 1505 (150Mhz)
The CRT of HP1740A is also very good.
A great feature of the HM 605 and other HAMEG analog oscilloscopes is the component tester.
It works like the HUNTRON tracker and is very useful for repair.
The 465 / 465B are very reliable, far more reliable than the 2235.
I recomend to install a fan in your 2235, like the 2236, because SMPS works very hot.
475 has 3 time bases, 2 mains (slow and fast) and 1 delay and is more complicated than 465 for this reason.
Probes of higher bandwith than 100 Mhz are expensive ...It is a nonsense to buy an high bandwith oscilloscope (200 or more Mhz) and use it with 100Mhz probes.
The 465/475 was designed to fit under aircraft seats.
So far I know, it was the 2335/2336/2337 not the 465/475.
HP\Agilent 546xxx are digital and not analog oscilloscopes...Not as simple as an analog one....their weaker point is the display : it is a little monochrome TV crt that has not a very long lifetime and hard to find.
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At one time, it was sought to sophisticate it and to make it perform functions for which it was not originally conceived as measures of tensions and time with high precision. These are the analog oscilloscopes with cursors.
Not all analog oscilloscopes use cursors for increased accuracy. Differential comparator inputs allow slideback voltage measurements and delta delayed sweep allows slideback time measurements.
Besides usually being more accurate, cursors are also easier to use so there is human factors engineering to consider. Automatic measurements are easier yet except when they automatically measure the wrong thing without notifying you. There is a big convenience factor here.
We also wanted to combine the advantages of the analog oscilloscope and digital, which produced "ugly little lame ducks" called combiscopes.
Do not waste your time and money with these lame hybrids.
I usually disapprove of unneeded complexity if only because of a loss in reliability but I make an exception for some of the Tektronix combination analog and digital storage oscilloscopes. The only reason I do not recommend them for beginners is that their extra complexity does make maintenance more difficult. In the case of the OP's question, they are also likely outside the budget limitation of $100 although I bought each of my 2230s for less than that.
The various 22xx combination analog and digital storage oscilloscopes use a separate "storage" board for their digital storage functions. If the board is removed or disabled, then they operate identically to the basic analog 2235 or 2225 model. Instead of a storage board, the 2236 and 2236A have a universal time/counter board which gives them almost uniquely useful capabilities shared with the 4 channel 2247A and 2252 models.
The 22xx oscilloscopes which include DSO functionality also have a readout in analog mode which is nice.
The DSO displays on these oscilloscopes are very high resolution making them clearer than you would expect. 100 points per linear centimeter or one division is 254 dpi which is considerably higher than most if not all modern DSOs. HP had some raster CRT based DSOs with unusually high resolution as well.
If you want the storage function or if you want to make accurate measurements, buy a digital oscilloscope, there is no match.
The analog oscilloscope is still very useful in various fields, in repair, in low precision measurements on complex periodic analog signals.
Slideback measurements may be more accurate than a DSO or cursor measurement but general purpose analog and digital storage oscilloscopes are not the instrument to use for precision. The old Tektronix 2440 series DSOs support dual delta delayed sweep which can be used for slideback time measurements but I have no idea why Tektronix included that.
Good DSOs are however much more convenient to use for measurements especially because of their automatic continuous measurement capability.
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The 475, 475A, and 485 may have a brighter and sharper CRT than the 22xx oscilloscopes.
Why is that ? Better or different CRT?
These CRTs are all basically the same design but the faster CRTs, especially the 485, have higher total acceleration voltages making them brighter and sharper.
The 465B and 485 have alternate dual delayed sweep. Most of the other 4xx oscilloscopes have mixed sweep which is not as useful.
So in 4xx series, these two are considered to be top models ?
The 465B (includes the 468) was the last 465 series design. The 485 is actually a year older than the original 465 but could be considered a performance and feature at any price design. I actually consider the 465M which is based on but very different than the 465 to be best of them except for the lack of alternate sweep.
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Besides usually being more accurate, cursors are also easier to use so there is human factors engineering to consider. Automatic measurements are easier yet except when they automatically measure the wrong thing without notifying you. There is a big convenience factor here.
This may be a concern on a production line where you have to make hundreds of measurements every hour, but not for a beginner.
If you need such convenience, buy a new DSO, not an old analog scope.
These analog oscilloscopes are at least 20 years old or more and reliability and maintenance are the greatest concern.
Other thing to remember: SMPS and SMD's electrolytic capacitors have well known reliability issues...try to avoid oscilloscopes with such problems.
High bandwith CRT's (like 2465) have distributed vertical deflection plates and this reduce the sharpness of the beam.
Oscilloscopes that where the best choice when they where new are no more the best choice 20 years later because they are to difficult to maintain.
How to measure the frequency of the displayed signal without cursors ?
My Hameg HM 605 has an Y output on the rear panel. I connected a low cost frequency counter to this output so I can measure the frequency of the A channel.
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It is not easy to compare CRT's about sharpness and brightness because you are limited by the risk of burning the phosphor and there is no way to measure it.
Then, it is a bit subjective.
But I think the best CRT I know is the one of my Hameg HM 1505 (150Mhz)
The CRT of HP1740A is also very good.
Tektronix used a scan expansion mesh in most of their CRTs sometime after the 50 MHz 547 which is great for increased deflection sensitivity which is important for high bandwidth and short CRT necks but has a side effect of making the traces thicker and causing ghosts. Some competing oscilloscopes did not allowing them to offer a sharper display. I think the one contemporary I have seen which looked obviously sharper than a 2235 was made by Hitachi.
One story I have heard is that TV stations were loath to give up their Tektronix 547s because the 7000 replacements with their scan expansion meshes were not able to resolve the NTSC horizontal sync pulses nearly as well.
Sharpness can be measured using a raster. Brightness can be measured by using a low repetition rate signal at a fast sweep.
The 465 / 465B are very reliable, far more reliable than the 2235.
I recomend to install a fan in your 2235, like the 2236, because SMPS works very hot.
Most of the problems in the 2235 series seem to be from the switching power supply which suffers from at least one mysterious failure mode (transformer damage from overheating?) but the original 2213/2215 power supply was just as bad if not worse. I do not really consider this a serious problem for someone with electronics experience and I suspect most of the failures are do to not replacing the aluminum electrolytic capacitors in a timely manner.
The 4xx series oscilloscopes definitely have an advantage here with their linear power supplies but that comes with the cost of increased weight.
475 has 3 time bases, 2 mains (slow and fast) and 1 delay and is more complicated than 465 for this reason.
I am not sure what you are referring to here. The delay function is part of the main (A or delaying) timebase. The 485 had an innovation shared with the 7B92 dual delaying timebase where the A and B timebases are swapped at high sweep speeds simplifying the sweep integrators.
Probes of higher bandwith than 100 Mhz are expensive ...It is a nonsense to buy an high bandwith oscilloscope (200 or more Mhz) and use it with 100Mhz probes.
I am not sure who is making them, but Texas (Hong Kong) sells the same inexpensive x10 probes up to 300 MHz which HP/Agilent/Keysight and some other oscilloscope manufacturers sell and include with their oscilloscopes and they seem pretty good.
HP\Agilent 546xxx are digital and not analog oscilloscopes...Not as simple as an analog one....their weaker point is the display : it is a little monochrome TV crt that has not a very long lifetime and hard to find.
I think these were the ones where HP made a special effort to almost double the horizontal resolution of the monochrome CRT which earned a patent.
The Tektronix went with using an LCD shutter to deliver color from a monochrome CRT because color CRTs were not good enough.
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Probes of higher bandwith than 100 Mhz are expensive ...It is a nonsense to buy an high bandwith oscilloscope (200 or more Mhz) and use it with 100Mhz probes.
And, as I'm sure you know, probing technique is at least as important as the probe.
The 465/475 was designed to fit under aircraft seats.
So far I know, it was the 2335/2336/2337 not the 465/475.
A little googling makes me think we are both wrong: it was the 453. http://readingjimwilliams.blogspot.co.uk/2011/07/scope-sunday-3.html (http://readingjimwilliams.blogspot.co.uk/2011/07/scope-sunday-3.html) (My 475 also says "Property of IBM")
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The 475, 475A, and 485 may have a brighter and sharper CRT than the 22xx oscilloscopes.
Why is that ? Better or different CRT?
These CRTs are all basically the same design but the faster CRTs, especially the 485, have higher total acceleration voltages making them brighter and sharper.
My favourite CRTs are the 485 and the HP1740A. The advantage of the hp1740a is that the screen is larger - but having a small screen didn't hurt the original Macintosh computers :)
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Besides usually being more accurate, cursors are also easier to use so there is human factors engineering to consider. Automatic measurements are easier yet except when they automatically measure the wrong thing without notifying you. There is a big convenience factor here.
This may be a concern on a production line where you have to make hundreds of measurements every hour, but not for a beginner.
If you need such convenience, buy a new DSO, not an old analog scope.
Most beginners think, possibly correctly, that automated measurements are a big advantage of DSOs. But, as we know, David's point about silently measuring the wrong thing is only too true.
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On CRO CRT's the best sharpest and brightest/crisp that I've had were:
1. Telequipment D83, a 50 MHz dual channel unit with a mainframe construction (w plugins) made by Tek after they acquired UK based Telequipment. It had the largest display of any CRO I've owned and the blue filter along with the sharp raster made it a joy to use. 15 KV acceleration voltage.
2. An Aussie made BWD, #452 IIRC, a nice and reasonably compact 50 MHz CRO, nothing special but the exceptionally sharp raster.
3. HP1740A, nice to work on but the trace pales in comparison to the above.
A few others, not worth mentioning.
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High bandwidth CRT's (like 2465) have distributed vertical deflection plates and this reduce the sharpness of the beam.
I do not think the distributed deflection plates have much to do with it. Distributed deflection plates are found on CRTs which also have scan expansion meshes simply because both help achieve high bandwidth. The increase in deflection sensitivity provided by scan expansion reduces the output voltage requirements of the vertical output amplifier. Scan expansion also allows for a shorter CRT neck
Oscilloscopes that where the best choice when they where new are no more the best choice 20 years later because they are to difficult to maintain.
Analog oscilloscopes are the best choice if their low used price is the difference between having an oscilloscope and not having one. They are also a good choice if high bandwidth is required at the lowest cost.
How to measure the frequency of the displayed signal without cursors ?
My Hameg HM 605 has an Y output on the rear panel. I connected a low cost frequency counter to this output so I can measure the frequency of the A channel.
Or count divisions. Or use delayed sweep. Or make a slideback measurement with delta delayed sweep. Or use a DSO to make an automatic measurement. None of these will be as accurate as a frequency counter but oscilloscopes are also not as accurate as voltmeters. Use the right tool for the job.
My favorite method is to connect the vertical output to the frequency counter and the B gate output to the frequency counter's arm input. Now a gated measurement of frequency and time can be made which is more accurate than a common DSO can achieve. Or a 2236, 2247A, or 2252 analog oscilloscope which have this capability built in can be used.
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Analog oscilloscopes are the best choice if their low used price is the difference between having an oscilloscope and not having one. They are also a good choice if high bandwidth is required at the lowest cost.
That succinct statement should be posted in any of the threads about "which scope should I buy". The earlier that posting, the shorter the thread will be :) (As if!)
Or count divisions. Or use delayed sweep. Or make a slideback measurement with delta delayed sweep. Or use a DSO to make an automatic measurement. None of these will be as accurate as a frequency counter but oscilloscopes are also not as accurate as voltmeters. Use the right tool for the job.
Yes Too many people have hammers and not screwdrivers - which is OK and is the inspiration for interesting engineering.
Too many people argue that you only need a hammer - which isn't OK.
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These CRTs are all basically the same design but the faster CRTs, especially the 485, have higher total acceleration voltages making them brighter and sharper.
My favorite CRTs are the 485 and the HP1740A. The advantage of the hp1740a is that the screen is larger - but having a small screen didn't hurt the original Macintosh computers :)
Over years I gotten used to CRTs in the the 22xx series (14kV) but then I brought my 7603 (15kV) out of retirement and despite its dimmer CRT, its large size is very nice. Then I picked up a 7834 (10kV or 12kV) which is bright for a storage CRT but roughly equivalent to the 7603. The first time I really noticed a difference was with the 400 and 500 MHz 7000 mainframes which have much higher acceleration voltages. My 7904 (24kV) makes every other oscilloscope I have look dim.
Most of the 465 series are 18kV and the 485 is 21kV.
There is more to brightness and sharpness than acceleration voltage like age, operating hours, and design, but acceleration voltage is a good place to start.
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475 has 3 time bases, 2 mains (slow and fast) and 1 delay and is more complicated than 465 for this reason.
I am not sure what you are referring to here. The delay function is part of the main (A or delaying) timebase. The 485 had an innovation shared with the 7B92 dual delaying timebase where the A and B timebases are swapped at high sweep speeds simplifying the sweep integrators.
From 475A service manual: two non delaying sweep generators, one slow and one fast, and one delaying sweep generator.
How to measure the frequency of the displayed signal without cursors ?
My Hameg HM 605 has an Y output on the rear panel. I connected a low cost frequency counter to this output so I can measure the frequency of the A channel.
Or count divisions. Or use delayed sweep. Or make a slideback measurement with delta delayed sweep. Or use a DSO to make an automatic measurement. None of these will be as accurate as a frequency counter but oscilloscopes are also not as accurate as voltmeters. Use the right tool for the job.
My favorite method is to connect the vertical output to the frequency counter and the B gate output to the frequency counter's arm input. Now a gated measurement of frequency and time can be made which is more accurate than a common DSO can achieve. Or a 2236, 2247A, or 2252 analog oscilloscope which have this capability built in can be used.
HM 605 has no delayed sweep, nor B gate output.
The first 2236 (serial number below more or less 10.000 24.000) have a very bad problem (very bad and fragile potentiometer D time position R1617 on counter/timer/multimeter board) who make it useless.
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475 has 3 time bases, 2 mains (slow and fast) and 1 delay and is more complicated than 465 for this reason.
I am not sure what you are referring to here. The delay function is part of the main (A or delaying) timebase. The 485 had an innovation shared with the 7B92 dual delaying timebase where the A and B timebases are swapped at high sweep speeds simplifying the sweep integrators.
From 475A service manual: two non delaying sweep generators, one slow and one fast, and one delaying sweep generator.
I see what you mean. I might have known this at one time but certainly forgot.
This may figure into the improvements Tektronix made in the 485 and 7B92 which only require one integrator for each sweep generator. For them, the delaying sweep generator is slow and the delayed sweep generator is fast. When the delaying sweep is used for the fastest sweeps, the delaying and delayed sweep generators are transparently swapped. This threw a for a loop a couple years ago on the TekScopes@yahoogroups.com email list when we were trying figure out how the delaying timebase generated the fastest sweeps..
Note that the release data are reversed here with the 475 and 475A coming after the 485 and 7B92 but I suspect they were handled by different design teams.
The first 2236 (serial number below more or less 10.000) have a very bad problem (very bad and fragile potentiometer D time position R1617 on counter/timer/multimeter board) who make it useless.
This would not be the first Tektronix oscilloscope design with trimmer potentiometer problems. Luckily trimmer potentiometers are easy to replace once the problem is found.
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This would not be the first Tektronix oscilloscope design with trimmer potentiometer problems. Luckily trimmer potentiometers are easy to replace once the problem is found.
It would be easy to replace if you could find a spare part....But this is a special trimmer...hard to find.
Look at the service manual and you will understand.
It is a trimmer used for Delta time position, that's a needed control potentiometer.
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The old Tektronix 2440 series DSOs support dual delta delayed sweep which can be used for slideback time measurements but I have no idea why Tektronix included that.
I just discovered this feature on my old 2430, it's well hidden. Beyond the basic horizontal/vertical controls, it's hard to love the UI on that scope :).
In any case it looks like it has quite accurate delays. The max delay time decreases with increased sample rate, suggesting that the base delay is counting off sample clocks, but the time resolution seems to well exceed the sampling clock.
I'm not sure how they'd achieve that sort of delay resolution, as clearly each of the dual delay captures have to be done on separate trigger events. Maybe the delayed signal is simply offset digitally post capture?
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This would not be the first Tektronix oscilloscope design with trimmer potentiometer problems. Luckily trimmer potentiometers are easy to replace once the problem is found.
It would be easy to replace if you could find a spare part....But this is a special trimmer...hard to find.
Look at the service manual and you will understand.
It is a trimmer used for Delta time position, that's a needed control potentiometer.
Oh, it is a control potentiometer and not a trimmer potentiometer. Based on the parts list which shows 4 different parts over time, it does look like Tektronix had problems with it.
The schematic shows a configuration which I would normally assume is a coarse and fine control potentiometer but the operating instructions describe and the photograph show a single control. I will have to ask over on TekScopes@yahoogroups.com what the deal is.
The old Tektronix 2440 series DSOs support dual delta delayed sweep which can be used for slideback time measurements but I have no idea why Tektronix included that.
I just discovered this feature on my old 2430, it's well hidden. Beyond the basic horizontal/vertical controls, it's hard to love the UI on that scope :).
In any case it looks like it has quite accurate delays. The max delay time decreases with increased sample rate, suggesting that the base delay is counting off sample clocks, but the time resolution seems to well exceed the sampling clock.
I'm not sure how they'd achieve that sort of delay resolution, as clearly each of the dual delay captures have to be done on separate trigger events. Maybe the delayed signal is simply offset digitally post capture?
The the delta delayed acquisition is a completely separate acquisition because of the short record length. It looks to me like the processor just alters the delay clock counter between acquisitions so two separate delayed acquisitions are captured. I could not find anything in the theory section about the frequencies used by the delay counter but I assume it is a fixed fraction of the sample rate.
I do not know why a cheap modern DSO could not do the same thing trivially but my guess is that the use case is not there.
On the 2247A series and the 2465 series, dual delta delayed sweep is used *instead* of cursors. You can use one or the other but not both at the same time and on these oscilloscopes, dual delta delayed sweep is activated by selecting the time measurement cursors so the front panel controls serve double duty.
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Oh, it is a control potentiometer and not a trimmer potentiometer. Based on the parts list which shows 4 different parts over time, it does look like Tektronix had problems with it.
The schematic shows a configuration which I would normally assume is a coarse and fine control potentiometer but the operating instructions describe and the photograph show a single control. I will have to ask over on TekScopes@yahoogroups.com what the deal is.
Yes, in serial number under 24.000, they used a trimmer as control potentiometer and that is bullshit because a trimmer's lifetime has a (very) limited number of operations.
Yes, it is only a single control, it does not match the schematic...and yes, Tektronix had problems with it...
This multimeter/counter board is very sophisticated, that's why I recomend not to buy 2236, but 2235 instead.
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The 465B (includes the 468) was the last 465 series design. The 485 is actually a year older than the original 465 but could be considered a performance and feature at any price design. I actually consider the 465M which is based on but very different than the 465 to be best of them except for the lack of alternate sweep.
So this one might be worth grabbing if you knew what you were doing:
http://www.trademe.co.nz/electronics-photography/other-electronics/other/auction-1230850237.htm (http://www.trademe.co.nz/electronics-photography/other-electronics/other/auction-1230850237.htm)
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The 465B (includes the 468) was the last 465 series design. The 485 is actually a year older than the original 465 but could be considered a performance and feature at any price design. I actually consider the 465M which is based on but very different than the 465 to be best of them except for the lack of alternate sweep.
So this one might be worth grabbing if you knew what you were doing:
http://www.trademe.co.nz/electronics-photography/other-electronics/other/auction-1230850237.htm (http://www.trademe.co.nz/electronics-photography/other-electronics/other/auction-1230850237.htm)
For the right price, absolutely it would be worth it but include the cost of buying a duplicate with the hope of combining the two to make one good oscilloscope. That auction does not really say anything which the photographs do not reveal. Maybe major portions of the instrument are missing inside.
Also consider how many of a specific instrument are available in your market which may take time. If it is rare like a 2212, 2214, or 2216 and requires repairs, then parts availability will likely be more of a problem.
However there is a lot of uncertainly in many auction descriptions. The seller may not be prepared to test the equipment at all or there could be a trivial fault which prevents any operation. The two 2230s I bought with the fallback intention of combining them were "as is" but except for an odd problem with one of them, they both worked fine. The only thing I knew from the photographs was that they powered on, presented an apparently working display, and showed no physical damage.
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From the Q&A the sellers replies:
Hi! I believe it is related to the HV power supply but I didn't trouble shoot it. It does not come on at all. The service manual should help if your are into this type of thing. As the title indicates it is a 100 MHZ scope.
No probes. I bought it faulty and I am selling it as is without attempting to repair it. I have a later model that I am working on.
I'd guess it's beyond him but I won't be grabbing it, if it was another 2465 or a B then I'd be interested.
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From the Q&A the sellers replies:
Hi! I believe it is related to the HV power supply but I didn't trouble shoot it. It does not come on at all. The service manual should help if your are into this type of thing. As the title indicates it is a 100 MHZ scope.
No probes. I bought it faulty and I am selling it as is without attempting to repair it. I have a later model that I am working on.
I'd guess it's beyond him but I won't be grabbing it, if it was another 2465 or a B then I'd be interested.
High voltage problems may require trivial repairs but are often difficult to diagnose.
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Happy New Year to all !
Thanks for tips.
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Finally, I have got Tek 2235!
First impression - it is smaller and lighter than I thought.
Second impression - yes, it is old man.
After 5 min working something has blown inside. :) It was C904 cap (EMI). Was changed on new one, also X2 rated but .22 mkF instead 0.068 mkF (I guess it is not so important there).
Also I have checked (by ESR meter) all electrolytic caps in power supply area - no suspicious caps were found, while I had been thinking otherwise..
Scope seem to work right but I need manual to check all options. Is there some short manual ?
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You sir made a good choice.
Just look for tek 2235 service manual.
Getting a vintage tek scope is a great idea. The manuals tek e are amazing, there are plenty of infos on the net and if something fails you can ask for help at the tekscopes yahoo group (those guys are amazing, they could have lead my grandma through the repair i did on my tek 2215, faulty dtb).
They are beatiful machines, and imo its a ton of fun repair them. A good project for a beginner (if its not a crt fault, dont want to touch that).
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The 2235 is one of the better options; it is newer than the 465 series but still fully documented.
The service manual and operating manual for the 2235 are separate and free scans of both are available at Tekwiki (http://w140.com/tekwiki/wiki/2235) among other places.
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You are really plugging the waspen-test.com thing. All you can write about :horse: