Loading ...
Sorry, an error occurred while loading the content.

Re: [SPAM]Re: [midatlanticretro] Oscilliscope Question

Expand Messages
  • DuaneCraps
    Bill; On most of the old analog scopes there is a knob in the center of the range selector knob to make the volts per division variable. for calibrated reading
    Message 1 of 3 , Jun 6, 2014
    • 0 Attachment
      Bill;
       
      On most of the old analog scopes there is a knob in the center of the range selector knob to make the volts per division variable. for calibrated reading it must be in the full CCW  position (there is a detent there and you can feel it click). The same thing applies to the sweep speeds.
       
      Duane
       
      From: billdeg
      Sent: Friday, June 06, 2014 4:32 PM
      Subject: [SPAM]Re: [midatlanticretro] Oscilliscope Question
       
       

      http://vintagecomputer.net/cromemco/system_one/repairs/Tek-5103N_.settings.jpg

      This is a picture of the scope.  If you were to match my settings to what I was talking about in my original post turn the left knob counter clockwise until the -2 at "2 o'clock" is at "10 o'clock".

      this might be a "you'd have to be there" kind of thing.  there may be a clue from the fact that the input itself is 47pF which is unlike the other scope I have.  The 5A20N is custom or something.  I think Herb was asking me about this too.  whatever, no biggie.  I think the point here is get a good scope and don't mess with a bad one.

      ----


      About my other question, a cap that reads 841uF is just that, they do not degrade from a lower rating to a higher rating as they fail (a cap that is labeled 590uF does not typically degrade to 800uF eventually.  Instead, the ESR goes up and out of spec.

      BIll

       

    • billdeg
      I actually answered my own question - I generated a sine wave, and split the signal. One line to the grounded tektronix probe and one to a grounded bare wire
      Message 2 of 3 , Jun 6, 2014
      • 0 Attachment
        I actually answered my own question - I generated a sine wave, and split the signal.  One line to the grounded tektronix probe and one to a grounded bare wire "probe".  Each probe was inserted into its own jack on an amp of the scope.  The wave that appeared on the screen was identical when I set the tek probe to -5 volts/division and the other to 5 volts/division, everything else being identical.  The probe is thus 10x.

        Then I found this:

        http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%205A20N%20Instruction.pdf



        B
      • DuaneCraps
        Bill, In case of doubt measure the probe end-to end. For a standard 1 meg ohm input scope the 10X probe will read 9 meg ohms. This forms a voltage divider
        Message 3 of 3 , Jun 6, 2014
        • 0 Attachment
          Bill,
           
          In case of doubt measure the probe end-to end. For a standard 1 meg ohm input scope the 10X probe will read 9 meg ohms. This forms a voltage divider where 9/10 dropped across the probe and 1/10 at the input to the scope. The old  tektronics  probes  had a center conductor of resistance wire so that the resistance was distributed through the length of the cable. Sometimes  I would run in to one someone had tried to shorten and made into a unknown X probe. Most of the other companies had the whole resistance in the probe itself. The trimmer capacitor is 1/9 th the input of the scope. If the scope input is 35 pf then the probe trimmer would be adjusted for 3.5 pf.
           
          Duane
           
           
           
           
           
           
          From: billdeg
          Sent: Friday, June 06, 2014 9:24 PM
          Subject: Re: [SPAM]Re: [midatlanticretro] Oscilliscope Question
           
           

          I actually answered my own question - I generated a sine wave, and split the signal.  One line to the grounded tektronix probe and one to a grounded bare wire "probe".  Each probe was inserted into its own jack on an amp of the scope.  The wave that appeared on the screen was identical when I set the tek probe to -5 volts/division and the other to 5 volts/division, everything else being identical.  The probe is thus 10x.

          Then I found this:

          http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%205A20N%20Instruction.pdf



          B

        Your message has been successfully submitted and would be delivered to recipients shortly.