Tektronix 6064 Differential Probe question

[moonlightbambi]

Hi,

I recently acquired a 6046 differential probe from tektronix.

I'm trying to use it measure current , across a .1 ohm resistor
current sensor.

I notice that there is over and under shoot. Coesn't really look real
to me.

I don't have a manual, unfortunately.
Looking for advice about how to adjust this thing, and what to expect
steps and results:
1. Turning a laser diode on and off at 3 kHz.
2. When I put it across the current sense resistor, I see an
overshoot on the rising edge, but shen I turn the probe around, I
don't see it. THe signal is about 50 mV It seems that the channels act
differently, not differentially.......
3. I adjusted the compensation on the .4 V square wave on the scope.
I left one side floating (or grounded) and adjusted the other to make
it square. It has a little overshoot too, and I can't get rid of it.
4. Strangly, when I turn the laser on, It ramps up, but the
"overshoot" is there even during ramp up.Perhaps it's pickup on some
other signal. But I don't see why a differential probe would do this.

Any ideas on the cause of this overshoot? I'm trying to measure in the
2 mv accuracy range.

Anyway, anyone have a manual?

thanks,

Adam

 

[Bob Koller]

Do you have a ground from the metal shell of the probe tip(s) to the circuit
ground?

This is necessary to prevent ringing.

bob
"moonlightbambi" <moonlightbamb@hotmail.com> wrote in message
news:62f73ca0.0404061230.66d60b44@posting.google.com...

Hi,

I recently acquired a 6046 differential probe from tektronix.

I'm trying to use it measure current , across a .1 ohm resistor
current sensor.

I notice that there is over and under shoot. Coesn't really look real
to me.

I don't have a manual, unfortunately.
Looking for advice about how to adjust this thing, and what to expect
steps and results:
1. Turning a laser diode on and off at 3 kHz.
2. When I put it across the current sense resistor, I see an
overshoot on the rising edge, but shen I turn the probe around, I
don't see it. THe signal is about 50 mV It seems that the channels act
differently, not differentially.......
3. I adjusted the compensation on the .4 V square wave on the scope.
I left one side floating (or grounded) and adjusted the other to make
it square. It has a little overshoot too, and I can't get rid of it.
4. Strangly, when I turn the laser on, It ramps up, but the
"overshoot" is there even during ramp up.Perhaps it's pickup on some
other signal. But I don't see why a differential probe would do this.

Any ideas on the cause of this overshoot? I'm trying to measure in the
2 mv accuracy range.

Anyway, anyone have a manual?

thanks,

Adam

 

[TekMan]

moonlightbamb@hotmail.com (moonlightbambi) wrote in message news:<62f73ca0.0404120934.4b59797b@posting.google.com>...

There is a ground from the probe ( a wire and an alligator clip) which
is grounded to circuit ground.

I, unfortunately, don't have the tip accessories, ( I'm working on
it). The tip of the probe does have a cylindrical ground around the
pointy tip. since I'm going directly from the tips to the circuit,
that point in the grounds isn't grounded.

Are you implying that they need to be grounded independently?

thanks!!!!!
adam

the p6064 needs to be grounded seperately.
And do not drive out the common mode voltage range (appr. 4 Volt
without tips, higher with 10:1 or 100:1 divider probe tips).


hth,
Andreas