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Re: [midatlanticretro] Re: Looking for a DSO/MSO

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  • Dave McGuire
    ... There were two issues there. The first was exactly what you interpreted it to be...that s solved by higher-end oscilloscopes like the Tektronix DPO
    Message 1 of 18 , Sep 26, 2012
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      On 09/26/2012 10:35 PM, joshbensadon wrote:
      > I will have to agree with Dave. I've tried using a digital scope but
      > I just couldn't figure out how to use it the way I wanted to. The
      > screen would flash 100's of different shots, all were accurate but
      > they happened too fast to be of any use. An analog scope would show
      > all those images overlayed on top of each other, the more identical
      > signals would create brighter traces, but it's the light traces that
      > I pay attention to, as these are the pulses that are out of the norm
      > ie of interest.

      There were two issues there. The first was exactly what you
      interpreted it to be...that's solved by higher-end oscilloscopes like
      the Tektronix "DPO" ("Digital Phosphor Oscilloscope") family. They seek
      to emulate the trace persistence behavior of an analog scope with
      long-persistence phosphor CRT. The emulated persistence is adjustable
      via a front-panel control. This works reasonably well. (I have a TDS3012)

      The other issue is one of triggering. Scope trigger circuits are
      nothing short of a black art. Some people think it's just a matter of
      adjustable-threshold comparators...until they try to trigger stably on a
      weird signal. Tektronix scopes have historically always had the best
      triggering. So, as above, the answer is "buy a higher-end scope".
      Incidentally, the triggering alone is why I don't bother with much other
      than Tektronix scopes.

      BUT...this is also illustrative of the point I made in my first reply
      in this thread. Analog scopes handle point #1 above as a matter of
      course, and higher-end, more expensive scopes handle point #2. Picking
      up an older, analog, but very high-end scope solves the problem handily.
      These were never "hobbyist" or "TV service" instruments...the 475, for
      example, cost $2650 in 1975, which is the equivalent of about $11,500
      today. You get what you pay for...but if you pick up a 475, you
      get...what someone else paid for. ;)

      Thanks to our culture's rather silly (but well-trained) idea that "if
      it's old, it's bad, and if it's not new, it's old", THINKING people can
      get the best test equipment ever built, timeless designs that will
      likely only become truly "obsolete" about the same time as
      semiconductors, for pennies on the dollar.

      -Dave

      --
      Dave McGuire, AK4HZ
      New Kensington, PA
    • Matt Patoray
      I ll throw my $.02 in, I ll concur on getting a good name brand scope. I have a Tektronix 7854 with 500 mHz dual trace plug ins. It is a great scope, well
      Message 2 of 18 , Sep 26, 2012
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        I'll throw my $.02 in, I'll concur on getting a good name brand scope. I have a Tektronix 7854 with 500 mHz dual trace plug ins. It is a great scope, well built all the way around. I would rather deal with age related issues on a quality scope then quality issues on a new scope.

        If you have never used one there is a great 2 hour tutorial on YouTube from the NJARC.

        Matt 

        Sent from my iPhone

        On Sep 26, 2012, at 10:35 PM, joshbensadon <no_reply@yahoogroups.com> wrote:

         

        --- In midatlanticretro@yahoogroups.com, Dave McGuire <Mcguire@...> wrote:
        >
        > On 09/26/2012 05:44 PM, J. Alexander Jacocks wrote:
        > > So, after being told, for years, that I needed to get an oscilloscope,

        I will have to agree with Dave. I've tried using a digital scope but I just couldn't figure out how to use it the way I wanted to. The screen would flash 100's of different shots, all were accurate but they happened too fast to be of any use. An analog scope would show all those images overlayed on top of each other, the more identical signals would create brighter traces, but it's the light traces that I pay attention to, as these are the pulses that are out of the norm ie of interest.

        Cheers,
        Josh

      • Mike Loewen
        ... A lot of us old pharts tend to favor hardware we ve worked with at past employers. I have a Tektronix 485 (dual-channel, 350MHz) scope and a HP 1650B
        Message 3 of 18 , Sep 27, 2012
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          On 09/26/2012 05:44 PM, J. Alexander Jacocks wrote:

          > So, after being told, for years, that I needed to get an oscilloscope,
          > I find that I finally have a need for one, to continue to work out the
          > power problems on my 68k Macs. My primary problem is that I know
          > _nothing_ about scopes. I have been told that I should get at least a
          > 100MHz scope, by various people, and that the sample rate should be as
          > high as possible.

          A lot of us old pharts tend to favor hardware we've worked with at past
          employers. I have a Tektronix 485 (dual-channel, 350MHz) scope and a HP
          1650B logic analyzer (35MHz State Mode, 100MHz Timing Mode, 80 channels).
          The biggest challenge in buying a used logic analyzer is finding the
          cables, pods and grabbers. As has been mentioned, you can't go wrong with
          Tektronix and HP.


          Mike Loewen mloewen@...
          Old Technology http://sturgeon.css.psu.edu/~mloewen/Oldtech/
        • J. Alexander Jacocks
          ... Thank you all very much for all this information! It is indeed well taken. I looked at the prices, and the functionality, last night, and I definitely
          Message 4 of 18 , Sep 27, 2012
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            On Thu, Sep 27, 2012 at 7:29 AM, Mike Loewen <mloewen@...> wrote:

            On 09/26/2012 05:44 PM, J. Alexander Jacocks wrote:

            > So, after being told, for years, that I needed to get an oscilloscope,
            > I find that I finally have a need for one, to continue to work out the
            > power problems on my 68k Macs. My primary problem is that I know
            > _nothing_ about scopes. I have been told that I should get at least a
            > 100MHz scope, by various people, and that the sample rate should be as
            > high as possible.

            A lot of us old pharts tend to favor hardware we've worked with at past
            employers. I have a Tektronix 485 (dual-channel, 350MHz) scope and a HP
            1650B logic analyzer (35MHz State Mode, 100MHz Timing Mode, 80 channels).
            The biggest challenge in buying a used logic analyzer is finding the
            cables, pods and grabbers. As has been mentioned, you can't go wrong with
            Tektronix and HP.

            Thank you all very much for all this information!  It is indeed well taken.  I looked at the prices, and the functionality, last night, and I definitely see the point that several folks have made, about the reasons for choosing an older high-quality scope.

            Do you know of older high-quality devices that are small?  Unfortunately, size really is an issue.  I live in a very small house, and my workbench is not all that much bigger than a Tek 485.  My workbench is located in a fairly small room, that is in a dormer, so the walls are angled, making it hard to stack vertically.

            Is there such a thing as a small HP/Tek scope?  I truly can't store a traditionally-sized rackmount/desktop scope.

            Thanks!
            - Alex
          • Mike Willegal
            I ve managed to solve quite a few tough issues with an $80 scope... Check out the blog post on this topic that I posted a couple of years ago.
            Message 5 of 18 , Sep 27, 2012
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              I've managed to solve quite a few tough issues with an $80 scope...

              Check out the blog post on this topic that I posted a couple of years ago.

              http://www.willegal.net/blog/?p=952


              Regards,
              MIke Willegal
            • J. Alexander Jacocks
              So, I ve finally picked up a scope. Don t have it, yet, as it s an eBay purchase, but hopefully will, soon. I did take some of the advice given, here, and got
              Message 6 of 18 , Dec 22, 2012
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                So, I've finally picked up a scope.  Don't have it, yet, as it's an eBay purchase, but hopefully will, soon.

                I did take some of the advice given, here, and got an HP 54506 300 MHz scope.  The size looks to be about right, and it appears to be in good condition.  Now, I just have to hope that the delivery courier doesn't destroy it.

                Dave suggested that I get Tektronix P6104 probes.  However, since I bought a 300 MHz scope, I assume that the equivalent probe would be the Tektronix P6131 probe?

                Has anyone here used scopes like the one I bought?  I'm trying to download the manuals from Agilent, but they seem to be having issues with their documentation server.

                Thanks!
                - Alex
              • Dave McGuire
                ... I used a 54501 for a long time...a good bit earlier but the same basic flavor. This being a digital scope...be careful. Be absolutely certain that you
                Message 7 of 18 , Dec 26, 2012
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                  On 12/22/2012 03:24 PM, J. Alexander Jacocks wrote:
                  > So, I've finally picked up a scope. Don't have it, yet, as it's an eBay
                  > purchase, but hopefully will, soon.
                  >
                  > I did take some of the advice given, here, and got an HP 54506 300 MHz
                  > scope. The size looks to be about right, and it appears to be in good
                  > condition. Now, I just have to hope that the delivery courier doesn't
                  > destroy it.
                  >
                  > Dave suggested that I get Tektronix P6104 probes. However, since I
                  > bought a 300 MHz scope, I assume that the equivalent probe would be
                  > theTektronix P6131 probe?
                  >
                  > Has anyone here used scopes like the one I bought? I'm trying to
                  > download the manuals from Agilent, but they seem to be having issues
                  > with their documentation server.

                  I used a 54501 for a long time...a good bit earlier but the same basic
                  flavor.

                  This being a digital scope...be careful. Be absolutely certain that
                  you understand the Nyquist limit and aliasing! People will say "that's
                  not a problem with modern scopes!" ...but in fact it is.

                  I've gone over the specs; it should be a damn fine instrument.
                  Congrats on the acquisition! Take the time to learn its capabilities
                  and limitations, well beyond what you might think (and some might say)
                  is "enough", and it will serve you well.

                  -Dave

                  --
                  Dave McGuire, AK4HZ
                  New Kensington, PA
                • J. Alexander Jacocks
                  ... Thanks, Dave! I ended up buying 4 Agilent N2863a probes, again following your advice to get quality probes. I m trying to download the manuals for the
                  Message 8 of 18 , Dec 26, 2012
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                    On Wed, Dec 26, 2012 at 3:15 AM, Dave McGuire <Mcguire@...> wrote:
                     

                    On 12/22/2012 03:24 PM, J. Alexander Jacocks wrote:
                    > So, I've finally picked up a scope. Don't have it, yet, as it's an eBay
                    > purchase, but hopefully will, soon.
                    >
                    > I did take some of the advice given, here, and got an HP 54506 300 MHz
                    > scope. The size looks to be about right, and it appears to be in good
                    > condition. Now, I just have to hope that the delivery courier doesn't
                    > destroy it.
                    >
                    > Dave suggested that I get Tektronix P6104 probes. However, since I
                    > bought a 300 MHz scope, I assume that the equivalent probe would be
                    > theTektronix P6131 probe?

                    >
                    > Has anyone here used scopes like the one I bought? I'm trying to
                    > download the manuals from Agilent, but they seem to be having issues
                    > with their documentation server.

                    I used a 54501 for a long time...a good bit earlier but the same basic
                    flavor.

                    This being a digital scope...be careful. Be absolutely certain that
                    you understand the Nyquist limit and aliasing! People will say "that's
                    not a problem with modern scopes!" ...but in fact it is.

                    I've gone over the specs; it should be a damn fine instrument.
                    Congrats on the acquisition! Take the time to learn its capabilities
                    and limitations, well beyond what you might think (and some might say)
                    is "enough", and it will serve you well.

                    Thanks, Dave!

                    I ended up buying 4 Agilent N2863a probes, again following your advice to get quality probes.  I'm trying to download the manuals for the scope, from Agilent (thank goodness they keep docs online for 20 year old equipment!), but their documentation service seems to be down for the holidays.  Oh well, since I had to get the probes from Malaysia, I probably won't be able to use the scope for a month or so.  That'll give me plenty of time to read the docs, before I use the scope.

                    What do you think of the GPIB interface?  I know that you can use that to print from the scope, and it seems like it can be used to control the scope, but is it worth me trying to get a USB-GPIB interface?  The card based (PCI, and PCIe) interfaces are seriously expensive, so I'd rather not get those.  I'm also not sure what software (other than LabView, which is way beyond my price range) is capable of driving the scope, over GPIB.

                    Thanks!
                    - Alex

                     
                  • Dave McGuire
                    ... Excellent. ... Yes, they re great about that. What s even better is they ve been scanning paper-only manuals and are supplying, free of charge, scanned
                    Message 9 of 18 , Dec 26, 2012
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                      On 12/26/2012 02:18 PM, J. Alexander Jacocks wrote:
                      > I ended up buying 4 Agilent N2863a probes, again following your advice
                      > to get quality probes.

                      Excellent.

                      > I'm trying to download the manuals for the
                      > scope, from Agilent (thank goodness they keep docs online for 20 year
                      > old equipment!),

                      Yes, they're great about that. What's even better is they've been
                      scanning paper-only manuals and are supplying, free of charge, scanned
                      docs of FIFTY year old equipment. Very nice!

                      > but their documentation service seems to be down for
                      > the holidays. Oh well, since I had to get the probes from Malaysia, I
                      > probably won't be able to use the scope for a month or so. That'll give
                      > me plenty of time to read the docs, before I use the scope.

                      Weird; I've never seen their doc system go down.

                      > What do you think of the GPIB interface? I know that you can use that
                      > to print from the scope, and it seems like it can be used to control the
                      > scope, but is it worth me trying to get a USB-GPIB interface? The card
                      > based (PCI, and PCIe) interfaces are seriously expensive, so I'd rather
                      > not get those. I'm also not sure what software (other than LabView,
                      > which is way beyond my price range) is capable of driving the scope,
                      > over GPIB.

                      GPIB is very handy. If you want to drop some coin and do a LOT of
                      cool stuff, get one of the Prologix GPIB<->Ethernet adapters. Screw
                      USB...with Ethernet, you can control your equipment from across the room
                      or from a hotel room in Albuquerque!

                      With that, you can do basic stuff (managing settins, pulling out
                      digitized waveforms, etc) with just some simple scripting. I'll talk to
                      you offline about other software possibilities.

                      -Dave

                      --
                      Dave McGuire, AK4HZ
                      New Kensington, PA
                    • J. Alexander Jacocks
                      ... To conduct a bit of thread necromancy, I just got another scope, that I couldn t resist buying, because it was really cheap. I picked up a Tektronix TDS380
                      Message 10 of 18 , Apr 20, 2014
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                        On Wed, Dec 26, 2012 at 4:13 PM, Dave McGuire <Mcguire@...> wrote:
                         

                        On 12/26/2012 02:18 PM, J. Alexander Jacocks wrote:
                        > I ended up buying 4 Agilent N2863a probes, again following your advice
                        > to get quality probes.

                        Excellent.


                        > I'm trying to download the manuals for the
                        > scope, from Agilent (thank goodness they keep docs online for 20 year
                        > old equipment!),

                        Yes, they're great about that. What's even better is they've been
                        scanning paper-only manuals and are supplying, free of charge, scanned
                        docs of FIFTY year old equipment. Very nice!


                        > but their documentation service seems to be down for
                        > the holidays. Oh well, since I had to get the probes from Malaysia, I
                        > probably won't be able to use the scope for a month or so. That'll give
                        > me plenty of time to read the docs, before I use the scope.

                        Weird; I've never seen their doc system go down.


                        > What do you think of the GPIB interface? I know that you can use that
                        > to print from the scope, and it seems like it can be used to control the
                        > scope, but is it worth me trying to get a USB-GPIB interface? The card
                        > based (PCI, and PCIe) interfaces are seriously expensive, so I'd rather
                        > not get those. I'm also not sure what software (other than LabView,
                        > which is way beyond my price range) is capable of driving the scope,
                        > over GPIB.

                        GPIB is very handy. If you want to drop some coin and do a LOT of
                        cool stuff, get one of the Prologix GPIB<->Ethernet adapters. Screw
                        USB...with Ethernet, you can control your equipment from across the room
                        or from a hotel room in Albuquerque!

                        With that, you can do basic stuff (managing settins, pulling out
                        digitized waveforms, etc) with just some simple scripting. I'll talk to
                        you offline about other software possibilities.

                        To conduct a bit of thread necromancy, I just got another scope, that I couldn't resist buying, because it was really cheap.

                        I picked up a Tektronix TDS380 2 channel 400 MHz 2GSa/sec, with 2 Tek P6114B probes.  It's in beautiful shape, and has a recent calibration, which was why it caught my eye.

                        However, it doesn't have GPIB, though it has room for the option.  Does anyone have a GPIB option 14 interface that they'd like to part with?

                        Thanks!
                        - Alex 
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