Yet another fast edge pulse generator

[Mechatrommer]

got it! unfortunately i guess our country needs to recover from covid pandemic thats probably why i got taxed + charges extra $40 for a tiny device anyway, i think this device is real... 100ps on SDA6000+LPA_BNC and 1.5ns on terminated Rigol DS1054Z. next.. i'll need to find a way to improve connection to my SDA6000's BMA input. my diy BMA-BNC shows similar performance as the Original Lecroy LPA-BNC

[exe]

LPA_BNC

What does LPA_BNC do?

[Mechatrommer]

LPA_BNC

What does LPA_BNC do?

BMA (ProLink) adapter for probes with BNC (ProBus) output https://www.digikey.my/product-detail/en/teledyne-lecroy/LPA-BNC/LPA-BNC-ND/4732810

[Converter]

got it! unfortunately i guess our country needs to recover from covid pandemic thats probably why i got taxed + charges extra $40 for a tiny device anyway, i think this device is real... 100ps on SDA6000+LPA_BNC and 1.5ns on terminated Rigol DS1054Z. next.. i'll need to find a way to improve connection to my SDA6000's BMA input. my diy BMA-BNC shows similar performance as the Original Lecroy LPA-BNC

Rise time should be measured in equivalent mode, not real time.

[Vestom]

Hi,
Just came across this interesting little device. Looks very useful, however, I wish it had a couple of extra features:
- Configurable frequency and duty cycle (e.g. by using the timers of the MCU). Will make it much more useful for TDR and other uses.
- USB-C instead of USB-B. USB-B is a bit bulky and old-school...

But I will likely buy one soon anyway :-)

[rhb]

Unfortunately, variable frequency and duty cycle would increase the jitter making them less useful for the primary use case.  USB-B has the great virtue of durability and there is no need to make these smaller.

I was able to get a couple of BNC units at 1 MHz instead of 10  MHz for TDR, but the nanoVNA has largely obsoleted them for TDR.  I think you can still get 3.5 and 2.48 mm pulsers at 1 MHz by request.

For the price it's the best assessment of a scope front end you can get.

Have Fun!
Reg

[Vestom]

Unfortunately, variable frequency and duty cycle would increase the jitter making them less useful for the primary use case. 

It would still meet its jitter specification by far (since there is none...) Why would jitter make it less useful for scope characterization? It should not impact jitter betwen trigger output and pulse output anyway.

Also wished:
- Dual balanced inverted/non-inverted SMA output for precise skew measurement/compensation and 100 Ohms balanced TDR.

[Berni]

When used on a sampling scope the jitter will mess up the waveform since the scope needs to sample the exact point on multiple pulses. Same reason for the SMA on the back of it, it provides a easy to get at trigger signal for these sampling scopes.

If you need differential then you could connect a balun to the output of it.

[Vestom]

When used on a sampling scope the jitter will mess up the waveform since the scope needs to sample the exact point on multiple pulses. Same reason for the SMA on the back of it, it provides a easy to get at trigger signal for these sampling scopes.

Yes, jitter between trigger and pulse will mess up the waveform on a sampling scope. But jitter on the clock before the trigger output should have no effect. It will only matter when performing clock recovery and trigging on the recovered clock instead of the signal itself.

What is the jitter performance of the current pulse generator?

[rhb]

Leo will have to answer that.  I should be able to measure it, but have not done so.  And Leo is  an EE.  I'm not.

Each unit comes with a plot of the step response using a CSA803A & 40 GHz SD-30 sampling head.  This is a very evil thing to do.  It provoked me to get an 11801.  I'm a retired seismic guy, so TDR is my natural environment.  I've had more fun with the 11801 and an SD-24 than any other piece of T&M kit.  After a year or two I finally broke down and bought an SD-30 which came Thursday.

Have Fun!
Reg

[Vestom]

It provoked me to get an 11801.  I'm a retired seismic guy, so TDR is my natural environment.  I've had more fun with the 11801 and an SD-24 than any other piece of T&M kit.  After a year or two I finally broke down and bought an SD-30 which came Thursday.

Have Fun!
Reg

Indeed, fun is what it is all about Nice piece of kit!

Most of the TDRs I have done have been 100 Ohm balanced, and I have fooled around with baluns, hybrids and whatnot. An expensive 4 channel VNA helps alot... But I can see that a "pocket pulse transmitter" could have been a nice and simple addition for measuring cable runs  . Maybe I will get around to make one myself - it doesn't have to be 40ps rise time

[rhb]

The nanoVNA has TDR capability now.  Hugen's new version, the H4, uses a '303 instead of the '103 part so there is more memory for features in addition to the 4" screen.  I haven't installed DiSlord's FW yet, but will eventually.

I built a pulser long ago using an ECL line driver.  I thought I'd failed miserably at the time, but I later discovered when the EE who gave  me access to a 485 at work and I measured it, we forgot to terminate it with 50 ohms.  IIRC when I measured it recently it was about 1.5 ns.  That was my introduction to how critical layout is at RF.

Have Fun!
Reg

[WORP3]

I've tried this new pulser from Leo which is just looking great. But during test I noticed that the pulse is negative going. This is not ideal as my scope is only DC coupled and only positive. Is there a simple way to invert the output of this pulser to a positive DC pulse?

[Tantratron]

Hello Europeans,

I was about to order one set to Leo but realized suddenly a possible higher cost issue due to BREXIT for my small french company. Has anybody (Germany, Spain, France...) purchased after 1st january 2021 the pulser, how did your country dealt with VAT, import duty taxes since the good comes from UK ?

Another question since I need to only test some of my TDSxxx oscilloscope (tekProbe-BNC input), it seems the BNC version is out of stock for a few months so if I decide to buy one generator, I need to pay quite an extra to get the SMA model then buy-add a SMA-BNC adapter provided by Leo.

Does anyone would have been any change done testing to check the different rise time difference of SMA model directly connected then with BNC adapter inserted from the SMA-pulser ?

Merci, Albert

[2N3055]

Hello Europeans,

I was about to order one set to Leo but realized suddenly a possible higher cost issue due to BREXIT for my small french company. Has anybody (Germany, Spain, France...) purchased after 1st january 2021 the pulser, how did your country dealt with VAT, import duty taxes since the good comes from UK ?

Another question since I need to only test some of my TDSxxx oscilloscope (tekProbe-BNC input), it seems the BNC version is out of stock for a few months so if I decide to buy one generator, I need to pay quite an extra to get the SMA model then buy-add a SMA-BNC adapter provided by Leo.

Does anyone would have been any change done testing to check the different rise time difference of SMA model directly connected then with BNC adapter inserted from the SMA-pulser ?

Merci, Albert

Albert,

Shariar did :



Maybe that answers your question.. Although result will highly depend on quality od adapter...

Regards,

[Tantratron]

Shariar did :



Maybe that answers your question.. Although result will highly depend on quality od adapter...

Many thanks @2N3055 where the adapter would be ordered as well from Leo's website http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=125_126&products_id=304 so no idea on how this matches with the SMA pulser but I'd expect or suspect loss or slower speed hence my hesitation to order besides the BREXIT nightmare now if we purchase T&M from UK

[Berni]

Unless it is a high performance >1GHz scope the adapter probably won't matter very much at all since the scopes own rise time will still dominate.

[Tantratron]

Well I do own a TDS794D which supposed to offer 2 GHz plus now I see one detail about Leo's SMA-BNC adapter, it will require another adaptor to actually fit my TDSxxx's BNC input. Maybe wisdom is wait for new stock of fast pulse with BNC and in the meantime, I'll figure the new import rules between UK and France.

[Berni]

Ah 2 GHz might get into it a bit if the adapter is a particularly bad one. I do have both the BNC and SMA versions of this pulse generator. But i probably wouldn't be fair to compare them since the BNC one on mine is the older revision that is slightly slower.

Maybe i will dig them up sometime and compare, can do it on a 3.5GHz scope or a 20 GHz sampling scope.

[2N3055]

Shariar did :

Maybe that answers your question.. Although result will highly depend on quality od adapter...

Many thanks @2N3055 where the adapter would be ordered as well from Leo's website http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=125_126&products_id=304 so no idea on how this matches with the SMA pulser but I'd expect or suspect loss or slower speed hence my hesitation to order besides the BREXIT nightmare now if we purchase T&M from UK

That adapter is good quality, but wrong gender for direct plug in to a scope...

Maybe something like this :

https://hr.mouser.com/ProductDetail/Pomona-Electronics/4288/?qs=4luskHXVU9Z9%252BIyNoZZ24Q%3D%3D

[Kibabalu]

Here results from a Keysight DSO-X 2014A (100MHz, 2GS/s) hacked to a Keysight DSO-X 2024A (200MHz, 2GS/s). Measurements made by using the SMA version of Leo's pulser with a rise time of approx. 28ps and a SMA to BNC adapter:

With 50 Ohm termination 1.5ns (2nd and 4th picture), without 50 Ohm termination 1.8ns (1st and 3rd picture).

The device meets its spec regarding the analog bandwidth, even without a proper termination. 

Sorry for messing around the sequence of the pictures 

[Kibabalu]

And here the result from a Tektronix TDS3034 (300MHz, 2.5GS/s) hacked to a Tektronix TDS3054 (500MHz, 5GS/s). Measurements made by using the SMA version of Leo's pulser with a rise time of approx. 28ps and a SMA to BNC adapter:

Rise time 603ps

The device clearly outreach its spec regarding the analog bandwidth. 

[Kibabalu]

and last but not least the spectrum

[natman69]

Hi, I am an EE but I worked only in IT field for decades. Now I have gray hairs and I want to spend time (for hobby) on my first love: electronics.

Last week I received the fast pulse generator.
First practical use: I want to use it to determine the real bandwidth of an oscilloscope using the BW (GHz) = 0.35 / rise-time (ns) formula.

Reading previous posts in this thread I have learned two hints to measure rise-time correctly:

1) set input impedance to 50 Ohm (if oscilloscope can change input impedance) or use a BNC 50 Ohm impedance adapter on oscilloscope input channel
2) don't use real time sampling. Instead, because the impulse is a 10MHz repetitive waveform try to use equivalent time sampling

Do I forgot something? Can someone put me in the right direction to do this measurement in the correct way?

Thank in advance.

[Kibabalu]

I'am using for digital scopes the formula BW = 0.4/Tr

If sampling time is small enough, there's no need for equivalent sampling, but usually it's necessary. At the end you need at least 5 to 8 sampling points within the rise time. But you should use averaging to remove effects of jitter and noise.