Hi,
I've recently bought a second hand Tektronix 2445A analog scope. I like it, have been playing around with it for a while now, read the manual and tried out different functions, but after a couple of measurements I got a bit confused.
Sometimes the read-out level the Tek is giving me (A1 in the upper left corner) differs from the level I measure with the Delta-V-measurement-knobs.
I've attached a picture as example: I measure an incoming alternating signal, triggered at lowest level (level-knob all the way to the left), division set to 500 mV/div and my Tek tells me the signal magnitude at trigger is .66V
However, if I measure it myself and put my delta-reference line (dotted line) on 0V, I get to read .5V if I put my delta-V-measurement line on the first division (which let's me assume these measurements are accurate, since division is set to .5V) , but when I move the measurement line up all the way to the actual signal , I get to read .78V. Which is something else than the trigger of the Tek is telling me in the upper-left corner (you can even see the difference quiet clearly here: my dotted measurement-line is at .66V, which is below the actual signal line, which, according to the trigger of my Tek, should also be .66V... )
So what IS the actual magnitude of my signal? What read-out should I trust? .66V as my trigger level tells me or .78V as I seem to measure? More important: can I "fix" this or what would be the correct workflow? Because when I have tow signals, both triggered and I'm interested in the difference between those signals, I'm confused, because when I align my measurement reference line to one of these signals, I get a different value to start with...
Thanks!
I've recently bought a second hand Tektronix 2445A analog scope. I like it, have been playing around with it for a while now, read the manual and tried out different functions, but after a couple of measurements I got a bit confused.
Sometimes the read-out level the Tek is giving me (A1 in the upper left corner) differs from the level I measure with the Delta-V-measurement-knobs.
I've attached a picture as example: I measure an incoming alternating signal, triggered at lowest level (level-knob all the way to the left), division set to 500 mV/div and my Tek tells me the signal magnitude at trigger is .66V
However, if I measure it myself and put my delta-reference line (dotted line) on 0V, I get to read .5V if I put my delta-V-measurement line on the first division (which let's me assume these measurements are accurate, since division is set to .5V) , but when I move the measurement line up all the way to the actual signal , I get to read .78V. Which is something else than the trigger of the Tek is telling me in the upper-left corner (you can even see the difference quiet clearly here: my dotted measurement-line is at .66V, which is below the actual signal line, which, according to the trigger of my Tek, should also be .66V... )
So what IS the actual magnitude of my signal? What read-out should I trust? .66V as my trigger level tells me or .78V as I seem to measure? More important: can I "fix" this or what would be the correct workflow? Because when I have tow signals, both triggered and I'm interested in the difference between those signals, I'm confused, because when I align my measurement reference line to one of these signals, I get a different value to start with...
Thanks!