Electronics > Metrology

Tektronix P6131 - Compensation


I got two of this probes with some equipment that I bought. I want to use them on my Tek 2465 but I cannot compensate them. The front end of the square wave droops a little and a lot. The cheap Chinese probe that I use is only good to 100Mhz, but compensates very good.
Is there something that can be done to fix this probe?

Can you test the probes on another scope?
The specs say that they are suitable for the 2465.

Yes, I tried on my digital Owon 60mHz scope and could not compensate either.

As I have a Tektronix 2465 and a p6131 probe I got all the manuals I could find, and maybe this could help you out?

For the manual with the pictures, click on link.

This is taken from the Tektronix P6131 manual.

This section contains procedures to adjust the P6131 probe low-frequency and
high-frequency compensations. Always perform the low-frequency compensation
adjustment before proceeding to the high-frequency adjustment.

To adjust the probe low-frequency compensation do the following:

1. Connect the probe output to the test oscilloscope vertical input.

2. Set the oscilloscope controls as follows:
Volts /Division 0.1 V (includes 10X probe attenuation)
Time/Division 1 ms
Input Coupling DC
Bandwidth Full

3. Connect the probe input with hook tip to the oscilloscope calibrator output.

4. Set the oscilloscope triggering for a stable display. The square wave should
be five cycles in length, four divisions in amplitude, and centered on-screen.

5. Using the low-reactance alignment tool, adjust C2010 to optimize the square
wave front corner edge. See Figure 6 for the adjustment location; see
Figure 7 for waveform optimization criteria.

6. Disconnect the test setup.

To adjust the probe high-frequency compensation do the following:

1. Connect the positive-going fast-rise output of the calibration generator to the
test oscilloscope with the precision coax cable and 10X attenuator.

2. Set the oscilloscope controls as follows:
Volts /Division 10 mV (includes 10X probe attenuation)
Time/Division 0.02 􀀀s
Input Coupling DC
Bandwidth Full

3. Set the calibration generator to produce a fast-rise output with a repetition
rate of 10 􀀀s (100 kHz). Adjust the output amplitude to produce a 5 division
display on the oscilloscope.

4. Adjust the oscilloscope triggering for a stable display and center the
waveform on screen.

5. Note the pulse shape and system aberrations for analysis in step 10.

6. Remove the precision coax cable from the test setup.

7. Remove the probe compensation box cover as described below.

Metal shell version: Unscrew the compensation box retainer nut
approximately two complete turns and lift the cover out and up. Press
the cable connector in firmly and retighten the retainer.
Plastic shell version: Pry off the darker portion of the plastic shell by
inserting your thumbnails into the seam between the two cover pieces;
then remove the lighter portion from the inner metal shield.

8. Connect the probe output to the oscilloscope vertical input.

9. Connect the probe tip through the probe-tip-to-BNC adapter and a 50 􀀀
termination to the positive-going fast-rise output of the calibration generator.
(The light gray probe-body shell must be removed before inserting the probe
tip into the probe-tip-to-BNC adapter.)

10. Verify that the high-frequency aberrations do not exceed +6% (5.30
divisions), –6% (4.70 divisions), or 9% (0.45% division) peak to peak, in
addition to the system aberrations noted in step 5 above.

11. If the probe aberrations are within tolerance, proceed to step 14 below. If the
probe aberrations are not within tolerance, continue with step 12 below.

12. Adjust R2021 for the best overall waveform flat response. See Figure 8 for
the location of all adjustments.

13. Adjust R2020, R2010, and C1010 for the best corner response without
ringing. See Figure 9 for the waveform area effected by each adjustment.

NOTE. High-frequency compensation adjustments affect probe bandwidth.
Following the compensation adjustments, verify the probe bandwidth specification
using the procedure on page 8. A small overshoot on the leading edge of
the pulse may be tolerated in order to meet the bandwidth specification. The
overshoot should not exceed the typical aberrations described in step 10 above.

14. Reinstall the compensation box cover by performing the procedure described
in step 7 above in reverse order.

15. Disconnect the test setup.

Thanks I will try this.


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