2nd picture, only a 10:1 probe connected on the scope, but not connected to any circuit.
The probe's tip is directly connected to the ground wire of the probe
You can see some 50Hz and HF
Note1: the amplitude of the 50Hz varries when I place the probe elsewhere
Note2: all the measurements have been made in storage mode, otherwise the camera would only take the spot and not the full screen
The probe's tip is directly connected to the ground wire of the probe
You can see some 50Hz and HF
Note1: the amplitude of the 50Hz varries when I place the probe elsewhere
Note2: all the measurements have been made in storage mode, otherwise the camera would only take the spot and not the full screen
Attachments
RFI?
Do you have any high pass filters that can be set?
It looks like the scope's sensitivity is set to maximum?
I have a 100 Mhz Hewlett Packard 'scope that does
have a visible internal noise floor with the input set
to the lowest range. I think that's normal.
Do you have any high pass filters that can be set?
It looks like the scope's sensitivity is set to maximum?
I have a 100 Mhz Hewlett Packard 'scope that does
have a visible internal noise floor with the input set
to the lowest range. I think that's normal.
What do you mean by RFI?
Yes the scope is set to its maximum sensitivity.
No I don't have any HP here, but I could build one it needed.
I didn't manage to measure the noise's frequency, since I can't get my scope to trigger on the signal 🙁
Yes the scope is set to its maximum sensitivity.
No I don't have any HP here, but I could build one it needed.
I didn't manage to measure the noise's frequency, since I can't get my scope to trigger on the signal 🙁
First of all: You won't hear this noise anyway, so why do you care ? 
2nd (and serious) try:
1.) The loop that you form with the ground wire will be able to pick up some noise and RF. If you a curious enough you might connect a shorted BNC to the input and see if there is an improvement.
2.) This small amount of noise isn't that bad at all with the scope set to its maximum sensitivity.
Regards
Charles
2nd (and serious) try:
1.) The loop that you form with the ground wire will be able to pick up some noise and RF. If you a curious enough you might connect a shorted BNC to the input and see if there is an improvement.
2.) This small amount of noise isn't that bad at all with the scope set to its maximum sensitivity.
Regards
Charles
Compared to the 150MHz Tek probe, my selfmade Kwak Probe (I hope elso won't mint if I call it this way 😉) that is made of a 1m RG58U coax cable with a 50R at the scope side, is dead quiet
You must probably make yourself a preamp with gain of 100 or 1000.Bricolo said:
AD797, LT1028 etc with batteries. Don't forget to a LP-filter so you only measure < 20 kHz.
Your GND cable is an antenna! You can twist it around the probe in order to get a smaller loop (=antenna).
Thank you for your help, guys
No I know how to get rid of this HF noise. But the 50Hz is still here, with the same amplitude 🙁
P-A: can you tell me more about this preamp? What's the advantage of using this?
No I know how to get rid of this HF noise. But the 50Hz is still here, with the same amplitude 🙁
P-A: can you tell me more about this preamp? What's the advantage of using this?
Just check the datasheets for the opamps. It's really simple and you can do a P2P or vero-board design.
The thing is that you have an environment with RFI noise and you cable picks it up. What happens if your short the inputs of the oscilloscope? Completely silent or still noise?
Don't forget that your scope also has digital noise with can be rather high. I used an old Tek 100 MSp scope with noise of 2-5 levels (of 256)!
Do you have your scope plugged in in an earthed mains outlet?
The thing is that you have an environment with RFI noise and you cable picks it up. What happens if your short the inputs of the oscilloscope? Completely silent or still noise?
Don't forget that your scope also has digital noise with can be rather high. I used an old Tek 100 MSp scope with noise of 2-5 levels (of 256)!
Do you have your scope plugged in in an earthed mains outlet?
Borrow someone else's 10x and see if the results are the same. I wonder if the shield in your probe has gone funny. This is a LOT more noise than I see with mine- on the 1 mV scale with the ground clip attached to the probe tip, I get an absolutely flat line.
- Status
- Not open for further replies.