Tektronix S-6 Questions

[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