I quote some older post about how was the noise related with the battery option or not.
There was differente results between me and rf-loop.
Now after my mods there is no any significant difference between battery or ac plug.
Unfortunately, mine situation is different from what we are expected!
With well charged battery from the worst to best the sequence is: battery (?400mV), battery+ac main(?300mV), ac main (?150mV) - Cheked by Owon Probe after Self Cal procedure and Probe adjustment.
Yes, this is unexpected result.
I have seen before:
(a) battery+ac most bad,
(b) ac without installed battery (battery out) less than a
(c) with battery alone without ac connected, less than b
It need some more investigation. I have some small suspects but too early to say.
Thanks Flash2light for this sharp photo.
TomC, you have a lot of improvement.
This was you have done after the psu changed and adapter mode, 68mV peak to peak and now you are 36mV about:
But I have some of questions-observations
1) you have different time set, the first was 1ms and now is 500us, normally there is no significant difference but if there is a periodic noise, the time makes the difference.
2) The back cover was closed at the two measurement of noise or they was different? Perhaps, this changed the noise.
3) some times the residues decrease the electricity of components. Personally, I have see some difference to noise after a good bath and very well drying with isopropylic alchool.
4) what you meaning with "Base line noise", from what I see there is no any BW limited or something else.
But please to all member, let us make measurements with same conditions like a protocol.
I copy the directions of rf-loop for comparisons reasons:
Procedure for measurent of GND Noise----------------------------------------------------
Make a Calibration procedure as manual refer (there is no nessesary if not the temperature variables ±5°C from the initial calibration)
Compensate the probe as manual described.
Change switch probe to 10x and set the same to the Probe Owon Menu (10X).
Connect together the probe tip and the probe aligator ground to Probe Comp GND.
Fix the cable of probe like the attachment photo.
Turn CH2 off.
CH1 to DC, 50mV/Div.
Push Trigger 50%
Set the Acquire Length to 1M and the Acqu. Mode to Peak
Set the Horizontal speed to 100us
Set the measurement to Voltage peak to peak (Vp to Owon) and write the value.