Tektronix P6131 - Compensation - Page 1
Forum section: electronics / general

author: dan3460
author_rank: Frequent Contributor
timestamp: February 29, 2016, 07:05:17 pm
content: 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?

author: Vgkid
author_rank: Super Contributor
timestamp: February 29, 2016, 11:44:11 pm
content: Can you test the probes on another scope?The specs say that they are suitable for the 2465.

author: dan3460
author_rank: Frequent Contributor
timestamp: March 01, 2016, 12:53:06 pm
content: Yes, I tried on my digital Owon 60mHz scope and could not compensate either.

author: Djinn
author_rank: Newbie
timestamp: March 01, 2016, 10:13:22 pm
content: 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.http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%20P6131%20INST.pdfThis is taken from the Tektronix P6131 manual.This section contains procedures to adjust the P6131 probe low-frequency andhigh-frequency compensations. Always perform the low-frequency compensationadjustment 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 msInput Coupling DCBandwidth Full3. Connect the probe input with hook tip to the oscilloscope calibrator output.4. Set the oscilloscope triggering for a stable display. The square wave shouldbe five cycles in length, four divisions in amplitude, and centered on-screen.5. Using the low-reactance alignment tool, adjust C2010 to optimize the squarewave front corner edge. See Figure 6 for the adjustment location; seeFigure 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 thetest 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 􀀀sInput Coupling DCBandwidth Full3. Set the calibration generator to produce a fast-rise output with a repetitionrate of 10 􀀀s (100 kHz). Adjust the output amplitude to produce a 5 divisiondisplay on the oscilloscope.4. Adjust the oscilloscope triggering for a stable display and center thewaveform 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 nutapproximately two complete turns and lift the cover out and up. Pressthe cable connector in firmly and retighten the retainer.Plastic shell version: Pry off the darker portion of the plastic shell byinserting 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 probetip into the probe-tip-to-BNC adapter.)10. Verify that the high-frequency aberrations do not exceed +6% (5.30divisions), –6% (4.70 divisions), or 9% (0.45% division) peak to peak, inaddition to the system aberrations noted in step 5 above.11. If the probe aberrations are within tolerance, proceed to step 14 below. If theprobe aberrations are not within tolerance, continue with step 12 below.12. Adjust R2021 for the best overall waveform flat response. See Figure 8 forthe location of all adjustments.13. Adjust R2020, R2010, and C1010 for the best corner response withoutringing. 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 specificationusing the procedure on page 8. A small overshoot on the leading edge ofthe pulse may be tolerated in order to meet the bandwidth specification. Theovershoot should not exceed the typical aberrations described in step 10 above.14. Reinstall the compensation box cover by performing the procedure describedin step 7 above in reverse order.15. Disconnect the test setup.

author: dan3460
author_rank: Frequent Contributor
timestamp: March 03, 2016, 01:03:50 pm
content: Thanks I will try this.