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Pocket-Sized 6 GHz 1 TS/s ET Scope

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joeqsmith:
Thank you for taking the time to document the command set.   I had a short conversation with the designer of the LibreVNA.  They also use USB but with a custom class.  Because I never ended up getting one, I spent minimal time looking into it.  I can tell you that your simulated serial interface is a LOT simpler to implement.  The basic command set suggests it would be fairly easy to develop custom software for it. 

joeqsmith:
After looking at so many low cost VNAs, I am curious what you have done for the connectors.  The  How many mate cycles are they rated for?  Are there concerns about torquing the SMAs? 

Left, my original NanoVNA.  Center, Mini-Circuits attenuator.  Right, my original LiteVNA.    Even though these are inexpensive, I still clean the connectors and minimize how much I touch them.  I also tend to keep the cables attached to them so these have not had a lot of mate cycles.  It does appear that the LiteVNA used a higher quality part.  When you are trying to sell a product for under $150, it is difficult to make a profit using 3.5mm end launch connectors.   

I have never broke a connector by torquing them with normal use.   I've had several people write me suggesting otherwise.  Any concerns on your product?

SJL-Instruments:
Thanks for asking. The exact connector we use is 901-10512-1 from Amphenol, rated for 26.5 GHz and min 500 cycles (full torque). This is about the best quality you can get for a brass SMA connector.

Torquing the SMAs (with a torque wrench) is not a concern. The aluminum housing is machined to close tolerances, so that the torque is transferred through the housing and does not flex the PCB more than a few thousandths of an inch.

However, if you open the case, torquing against the bare PCB may cause damage.

If anything does occur, worn/broken connectors are also a free warranty repair. Connector savers are always an option if you're paranoid.

joeqsmith:
My Signal Hound uses USB 3.  It reminds me of Longfellow, There was a little girl.  When she was bad she was horrid.  That pretty much sums up my experiences with USB. 

While I typically like headless equipment, the main problem all of them seem to have, they are headless..  :-DD   What happens is my PC is on my desktop and what I want to look at is on the bench.   The cable supplied with my Signal Hound was maybe 2' long.  They recommend a direct connection to the PC and warn against   extension cables or use of powered hubs.   How do I use it?  With a powered hub and extension cable.  Took some trial and error to get it stable, or as stable as USB can be. 

Looking at your manual to see what is included, I see no mention of cables.  Assuming you provide one, how long is it?  What interface connector is provided to connect to the PC?  My two PCs for example support USB3.0 type A connectors.  If you don't supply adapters/cables, and if it is critical, what guidelines do you offer? 

joeqsmith:
How about adding some basic measurements beyond what you have.  P-P for example.   Maybe have a look at what other scopes offer for basic measurements.   I like how even my 80's LeCroy can at the touch of a button throw up a hand full of parameters.   If you don't like those, they offer a pretty broad spectrum of measurements they can make. 

I think John's comment out his 11GHz $1000 DSO
--- Quote ---I find it difficult to use, mainly because of the software.
--- End quote ---
is a case where the UI is VERY important and can brake a product.  Limited features to achieve a simple interface is not IMO a good solution.  I want something feature rich, just easy to drive.   As you said, your software is easy to drive and doesn't require a users to read a novel to run it.  But it also lacks a lot of basic functions.   

****
Let me give you an example of what I consider a problem with your UI.  Say I have some signal that I want to look at.  I have some pre-trigger and want to find the falling edge.  I can't just capture unlimited data so I need to change the delay (timebase position) manually to hunt for it.   In order to do this, I have to type in the delay I want.  There is no inc/dec key.  No way to select how much to inc/dec by.... All manual and very painful.   That, or I am not understanding how it works.   I would expect all of the controls to have an easy way to adjust then outside of typing in the values.  Your trigger level for example allows me to set it by dragging the pointer.

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