Inaccurate Pk-Pk and 1 MOhm Impedence

Instruments HPS140 Handheld Pocket Oscilloscope
1

Hi,

I recently bought the HPS140. Before buying I called HPS140 US support to confirm if it has 1Mohm impedance input option and they said yes. I am not able to locate that setting.

Second, I see really inaccurate pk-pk measurement. For ex. when inputting an AC signal of +/- 20mV at 100 KHz I see pk-pk to be 60mV.

Please advice what I am doing wrong.

Thanks,
AK

2

Just wondering

Have you fully charged the battery on the scope?

3

The 1M input impedance is not a setting, it is a permanent feature of the input circuit.

20mV rms = 20 * 2 * sqrt(2) = 56.6 mV peak-to-peak so 60mV is pretty close.