Hi EEVblog forum members,
I just recently got a Tektronix AM503 amplifier and A6303 current probe on Ebay for a brushless motor driver project I am planning to start soon. The A6303, however, seems to have a DC offset that cannot be canceled with the DC level control on the AM503 at ranges below 0.1A/div, even after adjusting the DC offset pot on the probe. I have heard on the internet that there is a resistor on the probe that allows the DC offset to be further adjusted, but before I do that, I wanted to ask if it is normal for the probe to deflect ~100mA when a light pressure is applied at the end of the jaws (further with more pressure). If this is abnormal and indicates that the hall device is defective and unfixable I'll try to return the probe, but if it is normal I'm willing to just adjust the offset with the aforementioned resistor and call it a day (I got a very good deal on the probe, so even if I return it I would be paying double what I paid for this probe for an older probe in cosmetically worse condition). Other than this the probe seems to work fairly well, detecting DC and AC current with seemingly reasonable accuracy (although I cannot really measure accuracy until I head back home where I have a scope with 50 ohm termination). Also of note is that I don't have another probe to test the AM503 with, so it is possible that the problem lies with it instead. I have also been running the AM503 without a 50 ohm termination because I am away from home and don't have access to my normal scope with switchable 50 ohm termination.