Yet another fast edge pulse generator

[Jwalling]

Got mine a week or so ago. Build quality is excellent and it works great!

Results:
Agilent   54832D   1000         331   
Tektronix   TDS784A   1000         270   
Tektronix   TDS3052     500           620   
Tektronix   TDS694C   3000         106   
Agilent   54855A   6000         68

[HighVoltage]

Got mine a week or so ago. Build quality is excellent and it works great!

Results:
Agilent   54832D   1000         331   
Tektronix   TDS784A   1000         270   
Tektronix   TDS3052     500           620   
Tektronix   TDS694C   3000         106   
Agilent   54855A   6000         68

I had to look up the Agilent model number 54855A.
It is a real-time scope with a bandwidth of  7 GHz?
Nice result of 68 ps!

[grumpydoc]

Keysight DSO1024A



2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.

[Howardlong]

Keysight DSO1024A



2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.

Is the scope 50-ohm terminated?

[grumpydoc]

Keysight DSO1024A

2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.

Is the scope 50-ohm terminated?

No and I suspect that might have something to do with the response.

Disappointingly though for a 200MHz 'scope the DSO1024A has no built in 50 ohm termination.

However the path from Leo's pulser to the front end is so short that I suspect putting any external termination in will make things worse, not better.

I have a home made 50 ohm pass-through somewhere - I might dig it out and see if my suspicion is correct.

[grumpydoc]

I have a home made 50 ohm pass-through somewhere - I might dig it out.....

OK, so, makes a huge difference! 1.24ns

Trying to get my head around the interaction of the termination resistance and the input capacitance of the 'scope (18pf, so about 8.8 ohms at a GHz).



Fair bit of ringing though, similar with a T piece and the usual crappy 50 ohm terminator.



The data sheet gives 1.8ns but that is just a calculated figure (using 0.35/BW)

[WastelandTek]

hey Leo

Are you thinking the design iterations are pretty much done now?

[Leo Bodnar]

hey Leo
Are you thinking the design iterations are pretty much done now?

Hiya,
Pretty much so. 
Pulser performance went beyond what I originally wanted it to do. It even has an LED now.
Cheers
Leo

[WastelandTek]

hey Leo
Are you thinking the design iterations are pretty much done now?

Hiya,
Pretty much so. 
Pulser performance went beyond what I originally wanted it to do. It even has an LED now.
Cheers
Leo

right on, I think I am deserving a Christmas present 

[FriedLogic]

It's not that the performance of the BNC connector is unacceptable in itself, it's that the whole idea behind a fast pulser is to test fast hardware.  Having to use a BNC-to-SMA adapter with a fast DUT is certainly worse than having to use an SMA-to-BNC adapter with a slower DUT.

I accept your reasoning but I had problems with people not being able to find suitable USB cable locally.
Looks like I'd have to make and stock SMA version as well at some point.
Leo

Has anyone come across any readily available good and cheap SMA(f) - BNC(m) adaptors? (not surplus expensive ones, but cheap when bought new)

The main problem with most of the cheap BNC adaptors and plugs that I've seen is that they are missing the raised flange around the end of the ground connection on the plug, so don't connect well with the socket. The plating on a lot of them does not help much either.

I've sometimes bent the contacts out a little so that they connect better, but that's certainly not ideal.

[Leo Bodnar]

Has anyone come across any readily available good and cheap SMA(f) - BNC(m) adaptors? (not surplus expensive ones, but cheap when bought new)

The main problem with most of the cheap BNC adaptors and plugs that I've seen is that they are missing the raised flange around the end of the ground connection on the plug, so don't connect well with the socket. The plating on a lot of them does not help much either.

I've sometimes bent the contacts out a little so that they connect better, but that's certainly not ideal.

I use these https://www.digikey.co.uk/products/en?keywords=314-1184-ND when testing the pulsers.

[Berni]

I would buy another one of these if a SMA version becomes available.

I would guess that most people would still prefer it to be BNC since that makes it a great scope speed testing tool. But with the sort of speeds this thing is going at makes the rated few GHz frequency on a BNC seam a bit lacking. While SMA on the other hand goes in to the low 10s of GHz and is pretty widespread so i'm sure anyone that dabbled with RF has some SMA cables and adapters laying around.

You can probably make the PCB compatible with both SMA and BNC, then just solder BNCs on most of them while leaving a few without connectors. That way you can make small quick runs of the SMA version, but if there is not enough interest you can still go ahead and put BNCs on those too. Guess it would make sense to make the SMA version a few dollars more expensive for the extra trouble.

[HighVoltage]

I would buy another one of these if a SMA version becomes available.

Same here.
if you make the SMA version available, I will take one too.

[WastelandTek]

OK Leo, order 23042 in

Thank you and have a good holiday!

[EEngo]

Leo, thank you very much, my order arrived today.

the Lecroy DDA125 (aka LC684, 1.5GHz analog bandwith) was mentioned in your very first post with 295ps  , here are some additional measurements (see attachments):

Channel A: 248 ps
Channel B: 245 ps
Channel C: 249 ps
Channel D: 241 ps

perhaps someone with access could update the list, some more scopes will hopefully follow tomorrow (HP54616B, HM2008,Rigol MSO2202)

[Leo Bodnar]

OK Leo, order 23042 in
Thank you and have a good holiday!

Thank you for your order, it has shipped today.

Leo, thank you very much, my order arrived today.

the Lecroy DDA125 (aka LC684, 1.5GHz analog bandwith) was mentioned in your very first post with 295ps  , here are some additional measurements (see attachments):

Channel A: 248ps
...

My pleasure!  That was the older pulser model based on ADCMP***, its design has changed since then.  Amplitude increased too.
Leo

[Converter]

Hello, Leo,
Order Number is: 23079
Please send the latest version of the design.

Sergey.

[EEngo]

another measurements (see attachments):

HP 54616B (500 MHz): 540 ps 
Hameg HM2008 (200 MHz): 1,5 ns 
Rigol MSO2202 (200 MHz): 1,3 ns 

cool project, thanks leo! 

[Leo Bodnar]

cool project, thanks leo! 

You are welcome!
Thanks to everyone who ordered one.
All the orders have been shipped - usually within one working day from placing them.
Leo

[H.O]

The list has been updated, 94 entries this far.

[grumpydoc]

The list has been updated, 94 entries this far.

The DSO1024A entry needs correcting to 1240ps. It turns out that termination does matter after all**


** In other news: Pope is Catholic etc.

[richnormand]

Nice work H.O.
For the very fast systems (sampling scopes et al) you might have to note if the pulser is the early or the late version.
I would think that 40ps compared to 50ps  Tr will make a difference on a system with a 20ps risetime and such...

[H.O]

I'm sure it does but I can only put in the list what the user reports here, I unfortunately don't know which user has which version.

I usually have to Google scope sample rate and look at the attached photos/screenshots to figure out if internal/external/no termination has been used. When I don't know I leave that entry blank.

And, as you can see, for the very fast system the formula fails so the list is far from perfect.

I'll fix the DS1204A entry on the next round.

[texaspyro]

My TDS3034->3054 hack and THS730A measurements were done terminated at 50 ohms.

[EEngo]

thank you H.O. 

all my measurements (DDA125, HP54616B, HM2008 and MSO2202) were done with internal 50 Ohm termination.