I am having some problems trying to make some measurements. I am trying to measure some signals but an RF source keeps coupling into my oscilloscope lines. I even went so far as to put the device I?m trying to measure and the oscilloscope in an RF shielded box. It has cut down the RF a bit, but the problem is I have to connect the unit under test to the circuit outside the box, which is generating the RF. So no matter what I do there will still be some exposure inside the box traveling down the lines. I would like to measure a signal on the board without that RF creeping into the measurements but also be able to measure that same frequency on the on the signal in the circuit, if it is there.
With out the probe connected I see a significant signal. I can also connect the probe directly to a battery and see a significant signal. So it must be pretty powerful. Even using a differential probe brings no result. I know its not coupling into the scope itself because it does not trigger if the probe is disconnected.
Does anyone have any ideas?
Josh