Tektronix S-6 Questions

[Electro Fan]

Anyone happen to know what the proper configuration is for the back of a Tektronix S-6?

In the photo there is a 1cm long pin at location "1"; other Tek sampling heads simply have a Philips head screw in that location.  What is the function of this pin?  Does it clear or make contact with the insides of a 7S11 or 7S12?  (Is it for one or the other or both?).  Also, in location "2" there doesn't seem to be the usual copper or brass pin receptacle that is found in other S sampling heads - is that normal?

Thanks

[Electro Fan]

Not sure exactly what is happening here but it looks like even with a S-1 in the 7S12 using a S-52 Pulse Gen that the Tek 7000 is showing a pretty fast rise time.  Any suggestions on how to set things up / measure stuff is welcome.

[PA2HK]

Your picture shows a normal S-6 configuration. Sampling heads that offer internal triggering have a coaxial connector at that back that carries a high frequency triggering signal to the sampling plugins. Actual sampling is done at max 50kHz and those low frequency signals are carried via the card edge connector, high frequency signals being sampled never leave the sampling head. The S-6 sampling head has a spring loaded pin (marked 1 in your picture) and 3 screws at the back. Coaxial connector (hole marked 2 in your picture) is not required as the S-6 does not support internal triggering; triggering is normally done in a TDR setup via a pulse generating head like the S-52. That spring loaded pin is unique to the S-6 head and offers an additional ground/shielding connection to the plugin.

[Electro Fan]

Your picture shows a normal S-6 configuration. Sampling heads that offer internal triggering have a coaxial connector at that back that carries a high frequency triggering signal to the sampling plugins. Actual sampling is done at max 50kHz and those low frequency signals are carried via the card edge connector, high frequency signals being sampled never leave the sampling head. The S-6 sampling head has a spring loaded pin (marked 1 in your picture) and 3 screws at the back. Coaxial connector (hole marked 2 in your picture) is not required as the S-6 does not support internal triggering; triggering is normally done in a TDR setup via a pulse generating head like the S-52. That spring loaded pin is unique to the S-6 head and offers an additional ground/shielding connection to the plugin.

Thanks - The S-6 pin is indeed spring loaded! 

Back on the S-1/7S12/S-52 combination - the outer ring on the 7S12 has 3 settings 10x/1x/.1x.  With the S-1 the length of the pulse doesn't seem to change on the screen as the inner knob is changed - what seems to change is the intensified region of the waveform, along with the associated time div read out; does that seem correct?  And the knob with the fold out handle seems to also control the intensified region, yes?  (It behaves like the "Master Lock" tumbler knob on a 7B92A - but without the nice distance readout dial).

Thanks again!   

[Electro Fan]

Ok, need some help to determine if the multiple plugins are working properly - Please/Thanks.

Too many variables with too many unfamiliar products with too little knowledge and experience - so the plan is to isolate some variables.

Here is an image of a S-52 in a 7S12 outputting to the input of a 7A29.  Any chance this waveform looks like something that would be expected?  Something looks off to me but I don't know what I'm looking for   

I'm pretty confident the 7A29 and the 7B92A (which is out of sight but in use) and the Tek 7904 are all working properly, so I think we're down to seeing if we should have confidence in the S-52 and the 7S12.  If those are working A-OK than I'll try to tackle the S-6 next. 

Questions, comment, suggestion all welcome!

[Electro Fan]

Here is a known good pulse generator sending a pulse into the S-6 with the loop thru taking the signal from the S-6 to the input of the 7A29.  Signal looks ok - so maybe the S-6 isn't doing any harm to it - but I don't know if the S-6 is actually sampling anything or simply passing the signal thru?  If I could confirm the S-6 is functioning properly then I'd be down to confirming the 7S12 and the S-52.  Kinda feel like the saying that goes "we're lost but we're making good time." 

[Alex Eisenhut]

That pin on the S-6 moves the decimal point on the 6R1 digital readout because it's more sensitive. This is used in the 3S5 unit.
And the S-3A head with its more modest 1GHz bandwidth has the same pin, since I guess the probe attenuates.
The coax is a trigger pickoff, a copy of the front panel signal, but only for certain heads, the slower ones.

[Alex Eisenhut]

Here is a known good pulse generator sending a pulse into the S-6 with the loop thru taking the signal from the S-6 to the input of the 7A29.  Signal looks ok - so maybe the S-6 isn't doing any harm to it - but I don't know if the S-6 is actually sampling anything or simply passing the signal thru?  If I could confirm the S-6 is functioning properly then I'd be down to confirming the 7S12 and the S-52.  Kinda feel like the saying that goes "we're lost but we're making good time." 

The S-6 is pass-through, there is no trigger pickoff, so its best used for TDR with the S-52, at least that seems to be the most useful setup in the 567 and 6R1 read out.
Basically the S-52 triggers the scope and fires into the S-6, and you put your JUT (junk under test) on the other SMA and look for what comes back.

I wouldn't hang that much stuff off the S-6 connectors myself, there's a hybrid module in there and those SMAs make friction contact to the ceramic thingyjiggy inside.

Seems fragile. Maybe I'm too cautious, but it doesn't look fixable in there.

[Electro Fan]

Alex, thanks.  Just checking to see if you think this waveform looks normal?  EF

[Alex Eisenhut]

No, looks bad. Tunnel diode pulsers really make a step. You should see 0V, then a few nanoseconds of "feed through": a gentle rise, then the step, then it holds the level for a few microseconds then it slowly decays for the next cycle.

If that cable that goes off the picture really just connects the head to the vertical, that's a bad waveform. Bad amplitude too.

Here's the S-52 manual

http://w140.com/Tek_S-52_Manual.pdf

And might as well get the S-6 manual, it's tricky to find since I guess the OCR got the S wrong...

http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%2056%20Instruction.pdf

[Electro Fan]

Thanks Alex - I'm coming to the conclusion that the S-6 is not working properly.  I have one last idea though - I discovered the Bridge Balance adjustment.  The photo below happens to show it for a S-1 in an older scope but I believe the Bridge Balance adjustment is on most or all of the S heads including the S-6.  It looks like in this older scope it might have been adjustable with the scope covers off but it also seems like maybe this is something that was intended to be adjusted iteratively while the S head was outside the scope.  I'm going to try some settings through the range on the S-6 to see if it makes any difference.  Plz let me know if you have any experience with the Bridge Balance. 

I have all the manuals (S-1, S-6, S-52, 7S12, 7S11, 7T11) - they are pretty helpful but sometimes a bit hard to decipher; too bad they aren't pdf searchable but for decades latter beggars can't be choosers.

Also, just for the record I'm posting an image from the S-52 outputting to the S-1 in the 7S12 - look about right, right?  The image I posted looks pretty similar to the (A) image from the 7S12 manual - but maybe inverted?  I think the manual probably is showing a S-52 pulse sampled with a S-6 vs. my image which is the S-52 pulse sampled with a S-1.  I'm inclined to think the image shows that the S-52, S-1, and 7S12 are working (but so far the S-6 is not).  What do you think?  Thanks again.  EF

[Alex Eisenhut]

Yeah, that might be better; you have a ~200mV step in there, I don't know why there is a smaller step after. I'd have to set up my 567 to try it, can't do that right now.

I'd recommend picking the brains over at TekScopes at Yahoo.

[Martin.M]

Oh, there is an insider for Sampling Heads 

If possible I will have also some questions.
Here is a 564 in the collection, arrived with 3T2, 3S2, S1, S2, S3 complete set and S4

greetings
Martin

[EV]

Here are 2 pictures from my R7633 scope with 7S12 plugin and following modules S-6 and S-52 installed. Loop is terminated with 50 Ohm terminator and time distance is 0 in picture 7.

[Alex Eisenhut]

Here are 2 pictures from my R7633 scope with 7S12 plugin and following modules S-6 and S-52 installed. Loop is terminated with 50 Ohm terminator and time distance is 0 in picture 7.

Super good. The bottom trace is pretty much perfect IMO for a tunnel diode step. At least it looks like what all my other pulsers look like too. The feedthrough just before the step is normal for TD pulsers.

You should head over to Tekscopes for the real scoop on these things, I'm just a dabbler.

[Electro Fan]

Here are 2 pictures from my R7633 scope with 7S12 plugin and following modules S-6 and S-52 installed. Loop is terminated with 50 Ohm terminator and time distance is 0 in picture 7.

Mighty fine rise time.

Just noticed that the R7633 displays the "7S12" plugin as being plugged-in (and it also shows "Tek R7633"); is this a feature unique to the 7633 or is it something any 7S12 should do in any 7000 mainframe?

Also, you wouldn't happen to have a S-1 you could put in place of the S-6 to see what type of trace it would show with the S-52 in the 7S12 and R7633?  Thx

[dom0]

Just noticed that the R7633 displays the "7S12" plugin as being plugged-in (and it also shows "Tek R7633"); is this a feature unique to the 7633 or is it something any 7S12 should do in any 7000 mainframe?

Also, you wouldn't happen to have a S-1 you could put in place of the S-6 to see what type of trace it would show with the S-52 in the 7S12 and R7633?  Thx

Looks like 7M13 to me

[Electro Fan]

Oh -
http://w140.com/tekwiki/wiki/7M13
didn't know of this previously, Thx

[EV]

...
Just noticed that the R7633 displays the "7S12" plugin as being plugged-in (and it also shows "Tek R7633"); is this a feature unique to the 7633 or is it something any 7S12 should do in any 7000 mainframe?

Also, you wouldn't happen to have a S-1 you could put in place of the S-6 to see what type of trace it would show with the S-52 in the 7S12 and R7633?  Thx

Yes the left texts are made By 7M13 plugin. R7633 is rack model of 7633. Sorry I don't have S-1 any more. I had it some years ago but it was not working and I have teared it down.

[dom0]

Yeah, neat little documentation tool. Kind of sad that only few DSOs(*) have similar functionality. It would be quite handy to be able to annotate screens, just connect a keyboard to the USB port that all scopes now have and write away, or use an OSD and the knobs. But, no, let's not have that. Would be too easy, I guess.

(*) Windows scopes can do this of course

[Electro Fan]

Yep, a USB port for keyboarding on any scope would be good - for annotating and even just saving/writing file names. Could be wired or wireless.  Or maybe Bluetooth.

[EV]

I changed the cable between S-6 and S-52 to a semi rigid 15 cm cable. Here are 2 pictures about the rise time. It is now about 30 ps.

[EV]

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

[EV]

Here is picture about the rise time when S-4 and S-52 are installed to 7S12. S-4 and S-52 are connected with semi rigid 15 cm cable. Rise time is now a little under 30 ps ( about 28 ps).

[dom0]

Looks like both are very well inside their specs. If they had both identical rise times 28 ps system rise time would work out to ~20 ps component rise time, neglecting the cable.

[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

[EV]

You are wellcome! The rise time looks to be about 250 ps measured with S-1. S-52 is working correctly!

[EV]

By the way is that lighter part in the wave form only in the picture or can you see it also on the screen?

[Electro Fan]

By the way is that lighter part in the wave form only in the picture or can you see it also on the screen?

The lighter part is visible as being lighter (brighter) but it's perhaps 10 times more pronounced in the photo than what you would see in person.

[EV]

Are you sure that your S-6 is not working? You can try to use it like S-1 but install a 30 cm cable to upper sma connector and 50 Ohm terminator to the other end of the cable. I read the earlier posts but not noticed any evidence that it does not work.

You have also 7B92 installed? Maybe it generates that brighter part of the wave form???

[Electro Fan]

Are you sure that your S-6 is not working? You can try to use it like S-1 but install a 30 cm cable to upper sma connector and 50 Ohm terminator to the other end of the cable. I read the earlier posts but not noticed any evidence that it does not work.

You have also 7B92 installed? Maybe it generates that brighter part of the wave form???

Tried the S-6 with the upper cable and 50 Ohm terminator with the S-52 on the lower connector but no luck - just lots of noise and strange amplitudes.

Also tried the S-1 with the S-52 with the 7B92A removed (in the photo below) - the intensity still shows up - I'm pretty sure that it just a combination of the camera shutter speed and the rate of the sweep.

[EV]

Tried the S-6 with the upper cable and 50 Ohm terminator with the S-52 on the lower connector but no luck - just lots of noise and strange amplitudes.

Also tried the S-1 with the S-52 with the 7B92A removed (in the photo below) - the intensity still shows up - I'm pretty sure that it just a combination of the camera shutter speed and the rate of the sweep.

It looks that S-6 is broken, sorry!

You are probably right about the intensity variation. You are taking pictures when lights are on and the shutter open time is short. I take the picures when the lights are off and the room is quite dark.

[EV]

When I changed the cable which came with the 7S12 plugin to the semi rigid cable the rise time dropped from 38 ps to 28 ps. I think it is quite big drop. Picture about the cables attached.

[Electro Fan]

Do you know the part numbers for the original slower cable (Tektronix 61697?) and/or the faster semi rigid cable (also Tektronix?)?  How long are the cables?  Thx

38ps is great, another 10ps is really strong - nice work!

[EV]

Do you know the part numbers for the original slower cable (Tektronix 61697?) and/or the faster semi rigid cable (also Tektronix?)?  How long are the cables?  Thx

It is told in the manual that it is 1 ns semi rigid cable. I have not seen it but 1 ns cable is about 10 cm long.

In part list reads:
part number is 015-1017-01 and that it is 0.75 ns cable.

I used this: http://www.ebay.co.uk/itm/15cm-RF-Pigtail-SMA-Male-to-SMA-Male-Straight-Jumper-Cable-RG402-M-M-Connectors-/251800327928?hash=item3aa07816f8:g:6VQAAOSwm8VUtOij

[EV]

There is one on eBay which is 6 inch:

http://www.ebay.co.uk/itm/Tektronix-TEK-RF-Coaxial-Cable-015-1017-01-/172056078113?hash=item280f576721:g:YmEAAOSwJkJWkLLY

[Electro Fan]

Sorry, just to clarify, the number for the slower (38ps) cable that you used is 015-1017-01?

And this is the faster cable (that gave you 28ps)?
http://www.ebay.co.uk/itm/15cm-RF-Pigtail-SMA-Male-to-SMA-Male-Straight-Jumper-Cable-RG402-M-M-Connectors-/251800327928?hash=item3aa07816f8:g:6VQAAOSwm8VUtOij

[EV]

Sorry, just to clarify, the number for the slower cable that you used is 015-1017-01?

No, the slower cable is what I got with 7S12 plugin. It is not semi rigid and not Tektronix part.

[Electro Fan]

Sorry, just to clarify, the number for the slower cable that you used is 015-1017-01?

No, the slower cable is what I got with 7S12 plugin. It is not semi rigid and not Tektronix part.

Ok, your slower cable was something else.

But the faster cable was this?
http://www.ebay.co.uk/itm/15cm-RF-Pigtail-SMA-Male-to-SMA-Male-Straight-Jumper-Cable-RG402-M-M-Connectors-/251800327928?hash=item3aa07816f8:g:6VQAAOSwm8VUtOij

[EV]

Ok, your slower cable was something else.

But the faster cable was this?
http://www.ebay.co.uk/itm/15cm-RF-Pigtail-SMA-Male-to-SMA-Male-Straight-Jumper-Cable-RG402-M-M-Connectors-/251800327928?hash=item3aa07816f8:g:6VQAAOSwm8VUtOij

Yes, that is right!

[Electro Fan]

Theoretically with an S-4 you could squeeze out another 5ps for 23ps

Not sure how we get into the femtosecond range though

[EV]

I measured the Chinese semi rigid cable with 7S12 TDR (S-52 and S-6). It is 0.75 ns cable. Look at attached picture.

[Electro Fan]

I measured the Chinese semi rigid cable with 7S12 TDR (S-52 and S-6). It is 0.75 ns cable. Look at attached picture.

That includes your baseline 28ps?  If you remove the cable and terminate the pass through what does the otherwise same waveform look like?  Do the screen markings correlate to the poly markings on the 7S12 Time Distance scale?  Is your TD scale marked in meters or feet (I think Tek offered an option)?

[EV]

Here is picture when the upper SMA connector is empty. There is no cable or terminator.

[EV]

Here is picture when the upper SMA connector is terminated with 50 Ohm terminator.

[EV]

You can read the time from screen ar from Time Distance window. There are values time and length for Air and Poly isolations (I think). There is in the manual Fig 2.8 you can see that 1 us corresponds  492 feet in air and 324 feet in poly.

It means that:
1 ns corresponds 492 / 1000 x 12 x 2.54 = 15.00 cm in Air
1 ns corresponds 324 / 1000 x 12 x 2.54 =  9.88 cm in Poly

[EV]

Here I have connected to the upper SMA connector first 30 cm cable and to its other end 30 cm airline. You can see the difference in time betveen cable and airline as I calkulated in the previous thread.

[Electro Fan]

You can read the time from screen ar from Time Distance window. There are values time and length for Air and Poly isolations (I think). There is in the manual Fig 2.8 you can see that 1 us corresponds  492 feet in air and 324 feet in poly.

It means that:
1 ns corresponds 492 / 1000 x 12 x 2.54 = 15.00 cm in Air
1 ns corresponds 324 / 1000 x 12 x 2.54 =  9.88 cm in Poly

Supposedly light travels about 300 meters (~299.7 meters?) in air in 1us and 300 meters is about 984.25 feet - which is about twice 492 feet.  What accounts for the difference between 984 and 492?  Thx

[Electro Fan]

Hi EV,

I posted your image below to use as reference to adjust the 7S12.  (Before trying to fully figuring out how to read the TDR dial I thought it would make sense to align the scope traces as precisely as possible.)

Is line A intended to be just to the right of the boundary line or should it be exactly on the boundary line?  If to the right, how far?  (Or is that first pulse intended to be exactly 1us, and be aligned in the first time div?)

Was B intended to be at 100%?

Assuming B is at 100% should F be 50mV down from the 50% line (ie, at -50mV)?

Going for maximum precision, should the top of the E trace be just barely touching the bottom of the -100mV line or should the trace be centered vertically on the -100mV line?

Following the diagonal rise, should C intersect the 50% line at .4us into it's division - and should the width of that pulse be .8 us?

Thanks, EF

[EV]

Hi EV,

I posted your image below to use as reference to adjust the 7S12.  (Before trying to fully figuring out how to read the TDR dial I thought it would make sense to align the scope traces as precisely as possible.)

Is line A intended to be just to the right of the boundary line or should it be exactly on the boundary line?  If to the right, how far?  (Or is that first pulse intended to be exactly 1us, and be aligned in the first time div?)

Was B intended to be at 100%?

Assuming B is at 100% should F be 50mV down from the 50% line (ie, at -50mV)?

Going for maximum precision, should the top of the E trace be just barely touching the bottom of the -100mV line or should the trace be centered vertically on the -100mV line?

Following the diagonal rise, should C intersect the 50% line at .4us into it's division - and should the width of that pulse be .8 us?

Thanks, EF

The calibration instructions are in the 7S12 manual. Vertical calibation is done with scope 400 mV output. Horisontal calibration is done with scan button and Horiz pos and Sweep cal screws. You can read the there.

[Electro Fan]

Hi EV,

I posted your image below to use as reference to adjust the 7S12.  (Before trying to fully figuring out how to read the TDR dial I thought it would make sense to align the scope traces as precisely as possible.)

Is line A intended to be just to the right of the boundary line or should it be exactly on the boundary line?  If to the right, how far?  (Or is that first pulse intended to be exactly 1us, and be aligned in the first time div?)

Was B intended to be at 100%?

Assuming B is at 100% should F be 50mV down from the 50% line (ie, at -50mV)?

Going for maximum precision, should the top of the E trace be just barely touching the bottom of the -100mV line or should the trace be centered vertically on the -100mV line?

Following the diagonal rise, should C intersect the 50% line at .4us into it's division - and should the width of that pulse be .8 us?

Thanks, EF

The calibration instructions are in the 7S12 manual. Vertical calibation is done with scope 400 mV output. Horisontal calibration is done with scan button and Horiz pos and Sweep cal screws. You can read the there.

Yeah, yeah, read the manual - why read the manual when you can ask the teacher?   Just kidding; actually I have read the manual and I like your explanations a lot better

Regarding the vertical calibration is it your experience that each plugin should be calibrated or have you found that once you calibrate one plugin the others generally line up?  Thx

[EV]

Supposedly light travels about 300 meters (~299.7 meters?) in air in 1us and 300 meters is about 984.25 feet - which is about twice 492 feet.  What accounts for the difference between 984 and 492?  Thx

I think it goes forward and backward. So it goes 2 times 492.

[EV]

Regarding the vertical calibration is it your experience that each plugin should be calibrated or have you found that once you calibrate one plugin the others generally line up?  Thx

It is good to check the vertical and horizontal calibration. Check also 400 mV output. The s-52 pulse form is not critical in rise time and TDR measurements. You can adjust vertical gain to suitable value with fine adjustment.

[EV]

Here is delay line of 7M11 plugin measured with 7S12 (with S-52 and S-6). 7M11 has 75 ns delay line and 2X attenuator. Measured result is 150 ns but it must be devided by 2. So the measured delay is 75 ns as it should be.

[Electro Fan]

EV, Thanks for the additional timing posts.

I'm still trying to figure out what's up with the S-6.  Attached is an image from the signal generated by the S-52 using the pass through of the S-6 to the Rigol.  I had an attenuator in the path but it looks pretty normal on the Rigol - but when the S-6's sampled signal is viewed on the Tek 7904 it looks very different with lots of noise and distortions.  So I guess the pass through is independent of and before the sampling process. 

I'm on the lookout for another S-6 or maybe a S-4; if they were the same price would you go for the S-6 to get the pass through or would you prefer the S-4?  Thx, EF

[Electro Fan]

Inside the S-6 are five pots:

R30, R45, R50, r70, and C20 (I think it's C20).   R30 is accessible from the outside of the case - I turned that one down and it helped mildly, but still too much gain and plenty of distortion.

I know it's a long shot, but if the gain is dramatically too high - any of the remaining four pots a candidate for being turned down?

[EV]

I know it's a long shot, but if the gain is dramatically too high - any of the remaining four pots a candidate for being turned down?

What I have read about these S-6 the most common failure is that diode has been burnt. It is very sensitive for static electric shock. I have also one S-6 which does not work correctly. The wave form is distorted. I have not tried to fix it.

[EV]

Here are pictures about the wave forms from my faulty S-6 plugin. Upper SMA connector is free. Two first pictures don't look good. Next two look quite good but the last one is blurry. The rise time looks to be correct on the last picture.

If somebody knows what is wrong with this S-6 I am very interested.

[EV]

I'm on the lookout for another S-6 or maybe a S-4; if they were the same price would you go for the S-6 to get the pass through or would you prefer the S-4?  Thx, EF

If you are interested of timing (TDR) measurements S-6 is only possible. If you want to see external wave forms S-4 is good. Then you need also S-53 module instead of S-52.

[EV]

Here are pictures about the wave forms from my faulty S-6 plugin. Upper SMA connector is free. Two first pictures don't look good. Next two look quite good but the last one is blurry. The rise time looks to be correct on the last picture.

If somebody knows what is wrong with this S-6 I am very interested.

I installed a new hybrid assembly to this S-6 and now it works fine. It needs only a little adjustment. The hybrid has 6 diodes and some resistors inside.

[EV]

Here are 3 pictures about this hybrid. In the last picture the hybrid is opened.