measuring threw touch probe vs measuring threw coax input

yefj

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Hello,i have a system of a oscilloscope and signal generator .I took the input and split it into two .
one side went straight to the scope while the other wen to an SMA connected PCB board.
I used a probe to measure the SMA central pin .
When i looked at the scope i saw that my probed amplitude differs the coax input amplitude although they got the same input signal.
I think its because the probe is 1Mohm and coax probe is 50Ohm.
i want to know to properly understand the result i got on the screen.
Suppuse my signal generator is 50 Ohm and i have 1M Ohm probe on the scope side.
1.What is the equivalent circuit being created between the generator and osciloscope ?
2.At what place on the "circuit" i see the measured scope data?
Thanks.


 

Please use commonly understood technical terms. I guess "touch probe" refers to a standard 10:1 passive oscilloscope probe?

What do you mean with "coax probe"? I guess you are splitting the signal with a simple unmatched BNC T-adapter, feeding one coax cable to your PC-Board and the other to the oscilloscope? If so, what's oscillocope input impedance setting, what's circuit input impedance? What's signal frequency?

Are you aware that T-adapter gives predictable results only a low frequencies, e.g. < 1 MHz because it involves signal reflections and standing waves?
 

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