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Tektronix 2465A Oscilloscope Repair – Part 6

 

Tektronix 2465A Oscilloscope Repair – Part 6

Continuing on with our CAL 01 steps…

Step 2 – 6: Adjust timing markers for different sweep speeds

There are more timing adjustments in steps p – r. This time you are highlighting the 2nd and 10th markers, and overlapping the pulses.

 
CAL 01-r

Steps s – u are setting up a slower sweep, highlighting the 4th and 28th markers, and overlapping the pulses.

 
CAL 01-u

Steps v – x are a little different. You line up a marker on the left graticle, then use the Delta control to move the second marker where the first was at. Sorry for the blurry photos…

 
CAL 01-w

Steps y – aa appear to be setting up the x10 gain. You position the two cursors on the 2nd and 10th graticles, using the x1 gain control, then use the x10 gain control to set 10 markers in that space.

 
CAL 01-aa

Steps bb – dd work just like steps p – r.

Steps 7 -16: More Timing adjustments

Steps ee – ff runs you through a table of different periods, and using the “B” delay sweep to highlight and superimpose the indicated pulses like we did in one of the tests above.. That was all straightforward.

 
CAL 01-ff-07

When the table specified markers beyond the upper frequency of my function generator, I used my old trusty 8640B RF generator to send a sine wave at the specified period. Then I used the peaks of the sine wave as my markers.

 
CAL 01-ff-16 Generator

 
CAL 01-ff-16

 

Steps 17 – 29: x10 Horizontal Timing Adjustments

I don’t know exactly what steps gg – jj are doing. I could get the traces on my bench scope, but I don’t understand what they want me to do there, so I pretty much used the delta control to set the correct number of markers on the Tektronix scope, and left the Delay POS control where it sat, not affecting the bench scope with it. In the end, the timing seems good, so I’ll hope for the best…

For step jj-28, I set up a 50 Mhz signal from my generator and fed it through a BNC T connector to both channels. I don’t have the “Dual Coupler” called for in the procedure. But this is setting up timing anyway, so I just made sure to use equal lengths of coax to each channel.  It seemed to work, but I forgot to take pictures…

Remember, if you hit a “Limit” message on the screen, you have to redo the step until it is right, or the calibration will fail.  In all of my cases, if I hit a limit, it was because I was sending the wrong period or some other human error.

Step kk completes the CAL 01 procedure.

 

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