Tektronix S-6 Questions

[Electro Fan]

Here is wave form of S-52 from Rigol DS2202.

Thanks for the S-52 with Rigol DS2202 image.

Attached are images from the S-52 and a Rigol MSO2072A (running at stock 70MHz).

The first is terminated on the Rigol at 1M Ohms, the second at 50 Ohm (I think the S-52 output is 50 Ohms, or maybe that only applies to the pre-trigger output?).  Setting aside the impedance the waveforms still look different than yours.  It seems that the narrow pulse (at the trigger) might be a timing or interval marker and the wider pulse is the intended rise time measurement pulse?  These are just guesses, but the second pulse has a further spike beyond what your images show.  The frequencies shown in the counters are different also (2x) - this might account for the difference in the pulse width on the narrow "timing" markers as I referred to them.  Perhaps my S-52 is not operating properly?  Or maybe something else is at play?

Question:  any possibility that the S-52 pretrigger out plays any role?  Mine is not capped or terminated in any way.

I re-attached your image sandwiched between mine to make it easier to compare the images.  Thx

[EV]

The S-52 output is 50 Ohms. There is some problem with your S-52. I don't know what it is. The wave form should look like in the attached picture.

The amplitude is 560 mV to 1 MOhm input and 285 mV to 50 Ohm input.

[Electro Fan]

The S-52 output is 50 Ohms. There is some problem with your S-52. I don't know what it is. The wave form should look like in the attached picture.

The amplitude is 560 mV to 1 MOhm input and 285 mV to 50 Ohm input.

Thanks - I get that the pulse should be wider and that the frequency would change accordingly; just not sure which image you attached since it looks like mine but without the extra spike on the wide pulse (or if it is yours why does it have the narrow "timing pulse" and the incorrect frequency)?  Thx again

[EV]

Thanks - I get that the pulse should be wider and that the frequency would change accordingly; just not sure which image you attached since it looks like mine but without the extra spike on the wide pulse?  Thx again

Yes it is yours picture which I Photoshopped!

[Electro Fan]

Oh....   

Thanks 

(That was about the only answer that could have made sense - I just didn't think of it when I asked)

[Electro Fan]

EV, thanks for all your help.   Just checking to see if you might be up for a next phase in my sampling system project ?

As mentioned, I have a 7S11 and a 7T11 and the S-1; I realize you don't have a S-1 on hand but are there any tests you might suggest that I could do to confirm whether the 7S11, 7T11, and S-1 are working properly?  (And the 7S12 too.)  Unfortunately I don't seem to have a working S-52 or S-6 but I have other gear (pulse gen, function gen, Rigol scope, etc.) in case you could recommend some tests for the sampling plug-ins.  (I'm very confident the 7000 frame, 7A29, and 7B92A are working -- knock on wood some more).

My original intent was to use the sampling plugins to measure sub 100ps or so risetimes.  Before I chase more S-X heads I'd like to confirm if the 7S11, 7T11, S-1, and 7S12 are working ok.  Thanks for any suggestions.  EF

[EV]

I can try. Let's try first this 7s12 with S-1 and S-52. You can maybe get the correct pulse despite the extra pulse there. Connect S-1 to S-52 with short 15 cm cable. Set:
- time distace to zero
- multiplier to X10
- TME/DIV to 1 us
- REP pushed in
- LOCATE pushed in (you have it out in your pictures)
- mV/Div to 100
You should now see on the scope screen text:
100 mV    1 uS

The wave form is there also. The pulse should now be near the right side of the screen. Look at the attached picture. Take picture and put it here. I am now going to bed.

[Electro Fan]

Here is the 7S12 with S-1 and S-52 as per your settings plus one at 50mV (it shows the rise to the far left side of the screen).  Done with a 22cm cable - shortest I have.

[EV]

The wave forms look quite good. Now Multiplier to X1 and X.1 and take new pictures.

[Electro Fan]

Thanks - question:  what is the trick to getting a rising or falling edge that displays well on say 1ns on 1x to also display well (at the same time/distance) with 1ns on .1x?  Seems like if you can get an edge on 1x the same horizontal location should display the edge at .1x if the same time base (for example, 1ns) is used on both "magnifications".  Maybe something needs to be calibrated or adjusted to bring 1x and .1x into alignment? 

---

For example, I can get this falling edge at 200ps per Time Div on 1x but I can't get it at 200ps per Time Div on .1x ...?

[EV]

Let's look first if you get the pulse when the time distance is zero and multiplier X1 and X.1. The pictures should look like these.

[EV]

For example, I can get this falling edge at 200ps per Time Div on 1x but I can't get it at 200ps per Time Div on .1x ...?

Time distance is also multiplied by multiplier (10, 1 or 0.1). So it is 100 times shorter with X.1 than with X10. It means that you can see with multiplier X.1 only 1/100 part of the wave which you see with multiplier X10.

[Electro Fan]

First photo is the original time distance zero with the multiplier at 10x.  Second photo is with no changes except that the multiplier is changed to 1x.

[Electro Fan]

For example, I can get this falling edge at 200ps per Time Div on 1x but I can't get it at 200ps per Time Div on .1x ...?

Time distance is also multiplied by multiplier (10, 1 or 0.1). So it is 100 times shorter with X.1 than with X10. It means that you can see with multiplier X.1 only 1/100 part of the wave which you see with multiplier X10.

This is very helpful info - Thx!  But if the time/distance knob is working properly with the full range that would seem to imply that I should be able to duplicate your photos; in other words, I should be able to show the extreme left hand side of the waveform at both 10x and 1x (and also .1x), right?

I think I need to find the "easiest" part of the waveform to zoom in on from 10x, to 1x, to .1x - not sure where that is yet...  left size, middle, or right size.  (Normally I think it wouldn't matter but I think something is off with some adjustment on my setup.)

Or, are you saying that at the 0 time/distance setting the view of the edge should be retained at all 3 settings (10x, 1x, and .1x)?  Thx

Question:  is the amplitude also multiplied by the multiplier?  Or only the time/distance?  Thx

[Electro Fan]

Maybe slight progress

Here are two images at 10x and 1x - both were taken at the same time-distance:  .9925us

It looks like (in answer to my earlier question) that the multiplier does not effect the amplitude, only the distance.

Now I just need to find some time-distance position where I can display an edge using all three multipliers.

Note that the edge moved one time div between 10x and 1x - so either I have a calibration/adjustment problem or I'm not using the system quite right (operator error).

Update:  exciting find!  I lined up 10x on a time distance of exactly 1us; when I changed to 1x (which changed the time div from 1us to 100ns the edge moved over 1 tim div (100ns) - which I think is the time-distance relationship you said occurs with the multiple - so it's good!  Now I just need to find a way to shift from 10x to 1x to .1x without getting navigationally lost

EV, thanks for the hand holding / teaching on this stuff!!  EF

[EV]

Or, are you saying that at the 0 time/distance setting the view of the edge should be retained at all 3 settings (10x, 1x, and .1x)?  Thx

Question:  is the amplitude also multiplied by the multiplier?  Or only the time/distance?  Thx

You should see the left edge of the pulse with all 3 multipliers. It is the interesting part of the pulse. I can not see it in your picture 2 with 100ns time base. I don't know why the wave form in the picture has not same intensity. There are darker and lighter parts.

Try to rotate TIME/DIV knob clockwise with the same settings as in picture 2. Can you see the left edge of the pulse.

[EV]

Maybe slight progress

No progress! I think that they are not correct pulses. You must see left pulse edge by all 3 multipliers with time distance zero! Look at my pictures. The wave forms in these new pictures also don't have same intensity all over the wave. Why not?

[Electro Fan]

Ok, maybe not so much progress - but I think we're getting somewhere..... just not sure where - but it's fun trying to get there 

On a related matter, I think there is something goofy with either the DC Offset on the 7S12 or some part of the triggering system.  When I turn the multiplier from 10x to 1x the waveforms appear as in the last set of images; but when I change to .1x nothing appears on the screen.  However, when I then change the DC Offset significantly I can get a horizontal trace to display at .1x (but not some part of the waveforms as displayed at 10x or 1x).

Overall, I think there is some alignment that is needed for both the horizontal and the vertical.  As I recall from the manual there are some startup alignment steps.  I will revisit those to see if those steps might help.  I think I have to go to sleep so I will probably be signing off shortly.  Thanks again for all the deluxe help.

[Electro Fan]

Maybe slight progress

No progress! I think that they are not correct pulses. You must see left pulse edge by all 3 multipliers with time distance zero! Look at my pictures. The wave forms in these new pictures also don't have same intensity all over the wave. Why not?

OK, I will take it as the objective to get all three multiplier settings to display the left pulse edge.  Not sure what's up with the intensity - will try to figure that out too.

[EV]

If you can not you can not get left edge to the screen with all multiplier settings there is problem with S-52 or 7S12. There are calibrating instruction in the manuals but you need extenders for it.

However you can not use S-52 to see external wave forms. You need for it S-53 triggering module.

You can also use this S-52 to see rise time of your Rigol. Look at attaced picture

[EV]

Maybe there is no problem with the wave form you got from S-52 to your Rigol. The multiplier has not been X10. It has been X1 or X.1. Here is my picture when multiplier is X1. There is now also exra pulse.

[EV]

OK, I will take it as the objective to get all three multiplier settings to display the left pulse edge.  Not sure what's up with the intensity - will try to figure that out too.

There is also Fine Zero Set knob on 7S12 plug in. Ratate it fully clocwise!

[Electro Fan]

Maybe some progress now.

I think I had not set the Fine (Zero Set) knob properly.  Using that and the Horiz Pos, Sweep Cal, and Vert Gain adjustments and using your images as references I made some changes.  Still not quite right but for the first time all three settings X10, X1, and X.1 are rendering images.

(There is some intensity variation on the display but not nearly what you see in the photos - the significant intensity spots in the photos are caused - I think - by the particular time the camera takes the photo relative to the sweep.)

[EV]

Yes now they look good! There is still lighter part in the wave form. Set the SCAN knob fully clockwise. It may help.

Now with the settings in the last picture rotate TIME/DIV knob clocwise and adjust the time distance knob so that the left pulse edge can be seen. So you can get the exact rise time.

[Electro Fan]

Hey EV - You are the Man 

Check this out - after all the tweaking we finally have the original mission at hand:  a sub 500ps rise time

The whole purpose of this project was to get the scope running to push the limit on rise time measurements.  For the time being the limit is the S-1 but with a S-6 or S-4 it should now be possible to reach sub 50ps on rise time.

Thank you very much for all the help in getting the Tek 7000 and various plugins and sampling components running so well!

275 Trillionths of a second - how cool is that?   
And headed for about 30 Trillionths of a second 

PS, Major Thanks to EV and Special Thanks to All the Folks at Tektronix Who Designed this Equipment About 45 (Tek 7904) to 50 (Tek S-1) Years Ago