10 x probe vs 50ohm coaxial cable?

using a 50 Ω cable is ok under the following conditions:
you have a 50Ω source impedance (the point you are measuring is 50Ω), and the scope input has a 50Ω input impedance. You will see 1/2 of what the voltage would be with a high Z probe. In addition the point you are connecting to has to be capable of driving 50Ω.

But if the source is not 50 ohms, the cable will cause reflections and loading and distort the signal.


overall, the times you will use a 50 ohm cable are limited. Usually when you want to see the output of a signal generator directly, and it has a 50 ohm output jack. then you can use the 50 ohm cable, with a 50 ohm terminator at the scope end.

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There are different coaxial cable impedances as nicely 50 Ohm seventy 5 Ohm became already pronounced -- maximum regularly used to connect cable television interior your place (and to course cable television to families). a hundred Ohm controlled impedance twinax cable is utilized in some severe-end business instrumentation applications. sixty two Ohm coax is now and lower back used as RF feed to antennas. 50 Ohm cable is definitely one among the main user-friendly impedance for a vast variety of cable diameters and applicaions. .

If you use standard 50 ohm coax on a non-50 ohm cable, or if the length of your measurement cable is not an insignificant fraction of a wavelength, then your will run into problems with reflections or with the coax acting as an impedance transformer. The coax will load the device under test with a 50ohm characteristic impedance. The 10Mohm of the 'scope probe provides insignificant loading, and has high-frequency trimmer capacitor(s).

The attached article has great explanations. For really-high frequency work, there was a special 50 ohm coax measurement probe which has fallen from favor. See the reference for more details.