i bought a used scope and am looking for probes for it. its my first scope and i mostly want to learn how to use it correctly and become proficient in basic measurements. its an old tektronix 5103N with a 5A21N diff amp, a 5A18N dual trace amp and a 5B10N time base amp. the connections on the instrument all say
1Mohm, 47pf.does that mean i need probes with those values? could i use probes with more or less capacitance?
thanks in advance for your help, dc
Yes....you need to match the time constant in the scope (R*C) with that of your probes. Most probes are 1Mohm and they have a small variable capacitance that you can adjust with a screw driver. If you have too much capacitance on the probe, the probe scope interface will act as a high pass filter and too little capacitance it will act as a low pass filter. Generally you calibrate the probes with what you know is good quality square wave so that you see straight sides and a flat top on your scope.
You can also get probes that you can switch between 1Megohm and 10Meg ohms which is a good idea....the higher the input impedance to the scope the less likely you are to effect the circuit being measured. Once you switch to 10Megohms you might need to recalibrate the probe though.
Nah. Just get a oscilloscope probe*. 1 Megohm 47 pF is the impedance of the scope. If you stick a ohmmeter to the inputs of your scope, 1 megohm is what you'll get.
*One end is a probe with a metal hook (the "red" lead), and a ground alligator clip/hook. The other end is BNC male connector to plug into scope. The cable shield is ground.Note that if your scope plugs into wall AC receptacle, the chassis is earth grounded. Therefore, the ground clip/hook is also earth grounded. So don't connect ground clip/hook to non-zero source/signal!
Steve Minshull wrote in news:e13dae$fnm$ snipped-for-privacy@hermes.shef.ac.uk:
It's the 10 Megohm probes (10X) that have the comp adjustment,1Meg probes(1X) are little more than coax with a fancy tip,and a lot of capacitance.
Yes,less resistive and capacitive loading on the circuit under test.
You adjust it at 10X,not at 1X.
-- Jim Yanik jyanik at kua.net
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