US$200 VNA kickstarter launched

[xaxaxa]

Is it possible to bypass the filter?

That's only half the problem; you also need a synthesizer that can reach near DC, and those are nearly nonexistent. The max2871 has one of the widest frequency coverage and even then it only goes down to 23.5MHz.

It is possible to use a prescaler or DDS solution; if i use a lower IF as well i might be able to do <1MHz. That is what I might consider for the next version once i get the main product delivered.

[xaxaxa]

Looks like my kickstarter has flatlined;

If anyone could help me spread the word or give me some suggestions about where else to advertise it I would really appreciate it!

[TheSteve]

It is probably too late but one option is to send a prototype to someone who produces youtube content. Dave is an option, or Shahriar from the Signalpath (if they are interested of course). They are obviously very busy though and don't produce instant content. The biggest thing you have going for yourself is the price. I have two network analyzers already or I'd likely be interested. Either way I am routing for you as you're local to me.

[Jay_Diddy_B]

Hi,

You can see a chart of the progress on this website:

https://www.backerkit.com/projects/1759352588/xavna-a-full-featured-low-cost-two-port-vna

This is their prediction at the moment:



I would keep the screenshots and the progress reports coming. I think you need a few more points on some of the measurements to get smoother curves.

Regards,

Jay_Diddy_B

[xaxaxa]

Hi,

You can see a chart of the progress on this website:

https://www.backerkit.com/projects/1759352588/xavna-a-full-featured-low-cost-two-port-vna

This is their prediction at the moment:

I think that graph might be a bit overly optimistic 
Currently it's already dropped off to less than one backer per day which means I need a wider distribution channel if it is to reach goal.
Any suggestions?

[trevwhite]

Hi,

You can see a chart of the progress on this website:

https://www.backerkit.com/projects/1759352588/xavna-a-full-featured-low-cost-two-port-vna

This is their prediction at the moment:

I think that graph might be a bit overly optimistic 
Currently it's already dropped off to less than one backer per day which means I need a wider distribution channel if it is to reach goal.
Any suggestions?

You could tag it as an Internet of Things tool for everyone who wants to tune their antenna? Get it mentioned in hackaday? See if Elektor mag would do a comment on it?

Can you do a video of you tuning an actual Wi-Fi board antenna or a Bluetooth board antenna? That might tag some interest/generate traffic. It would show a really useful example of how people can use it and experiment with it.





Thanks

Trev

[phil]

+1 on the video.

You could try and submit it to https://www.rtl-sdr.com. All this cheap(ish) SDR stuff is very popular with the maker/hacker folks. There are quite a few out there building their own front ends or antennas and looking for an affordable VNA.

[usagi]

+1 on the video.

You could try and submit it to https://www.rtl-sdr.com. All this cheap(ish) SDR stuff is very popular with the maker/hacker folks. There are quite a few out there building their own front ends or antennas and looking for an affordable VNA.

lack of <140mhz is going to dampen interest in this device by the sdr crowd.

[TK]

In my opinion, Antenna tuning can be done using a spectrum analyzer with noise generator or tracking generator and it is top priority for most HAM and SDR users.  VNA is a desired equipment but not top priority.  So, they will first buy a nice spectrum analyzer, then more HAM equipment, and lastly a VNA.   You need to show them they NEED one so it makes it top priority.

Your project is open source and if you make it attractive for the the user community to hack and improve it, you will have a differentiation.  But you need to be prepared for the clones from China if you are successful.

You can take a look at HACKRF (Great Scott Gadgets) and how they promote the item online.  There are lots of clones now selling on eBay as it is also open source.

[homestea]

I think if it had a nice enclosure (sheetmetal, molded, etc) to make it look more like a finished product it would have way more appeal.  I know that this will add cost but you could make it a higher cost tier backing for including the enclosure.   If you need help I’m a Mechanical Engineer with extensive experience with designing enclosures.  I’d be willing to help in return for a free kit or something like that. 


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[trevwhite]

I think if it had a nice enclosure (sheetmetal, molded, etc) to make it look more like a finished product it would have way more appeal.  I know that this will add cost but you could make it a higher cost tier backing for including the enclosure.   If you need help I’m a Mechanical Engineer with extensive experience with designing enclosures.  I’d be willing to help in return for a free kit or something like that. 


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I think that Is a good idea and a decent offer if the enclosure can be made cheap enough. Might be cheaper to drill an off the shelf enclosure though  if numbers are low.

Maybe something could be 3d printed?

Thanks

Trev

[xaxaxa]

I've submitted the project to hackaday and rtl-sdr blog;

@homestea is helping me with the enclosure, and I plan to introduce a version with a proper metal enclosure. The default version will most likely have an acrylic case too, but I didn't promise that on the campaign just in case it doesn't fit in the budget. It is mentioned on the kickstarter page.

The hardware and software are both open source and community involvement is welcome; especially on the fpga hdl part there are a lot of possibilities (maybe a sdr mod?)

The video is a good idea; will do that when I have a good lab environment (i'm currently out of town).

[rhb]

A VNA in a plastic box is an oxymoron.  You should design the board around a suitable standard enclosure taking into account cooling and shielding.  I very much doubt that someone who would be interested in owning a VNA would be willing to house it in a plastic box.  They certainly *ought* to know better.

I bought a LimeSDR and am still struggling with the problem of packaging it properly.  I'd be much more interested in a more capable unit than a VNWA 3E in a well designed enclosure at the same price point than a $200 board that will require considerable thought and effort to package properly.  You can always sell the board without the enclosure, but at least offer a suitable extruded enclosure with punched and screened end panels.

The LimeSDR enclosure offerings were ridiculous, the acrylic was stupid and the metal was absurdly expensive and not suited for general experimentation.

I think your $200 price point is too ambitious.  For a prospective buyer the difference between $200 and $400 is less important than getting a usable product.  It needs to become a regular product which means you need to factor in a reasonable profit margin for whomever is going to sell them.  If it's an orphan product there won't be any bug fixes.

[xaxaxa]

As mentioned, there will be a version with a metal enclosure. Bare board with standoffs and cover is also perfectly usable since the product will come in a cardboard box that you can easily carry it around in. The terasic fpga dev boards are a good example of this.

Not everyone can afford or justify $400+ and to some people (like me) it is a huge difference. Plus, the main selling point is not the price but the much improved accuracy and temperature drift compared to existing products. I'm not going to quote specific numbers here but you can be assured that my profit margin is not razor thin.

A VNA in a plastic box is an oxymoron.  You should design the board around a suitable standard enclosure taking into account cooling and shielding.  I very much doubt that someone who would be interested in owning a VNA would be willing to house it in a plastic box.  They certainly *ought* to know better.

I bought a LimeSDR and am still struggling with the problem of packaging it properly.  I'd be much more interested in a more capable unit than a VNWA 3E in a well designed enclosure at the same price point than a $200 board that will require considerable thought and effort to package properly.  You can always sell the board without the enclosure, but at least offer a suitable extruded enclosure with punched and screened end panels.

The LimeSDR enclosure offerings were ridiculous, the acrylic was stupid and the metal was absurdly expensive and not suited for general experimentation.

I think your $200 price point is too ambitious.  For a prospective buyer the difference between $200 and $400 is less important than getting a usable product.  It needs to become a regular product which means you need to factor in a reasonable profit margin for whomever is going to sell them.  If it's an orphan product there won't be any bug fixes.

[xaxaxa]

mini-update: iteration 2 prototype ready to be sent to the fab. Attached is the top view of the PCB.

[HalFET]

Why would a VNA in a plastic box necessarily be worse? If you manage to shield the critical signal paths within the inner layers of the PCB I don't see why you couldn't get an acceptable performance level? Don't expect a $200 unit to perform like a $2000 one. But realistically speaking, do you need it to? There's no need to beat Keysight's FieldFox units I think. But actually, another question: Did you check prices at any other board house? Most of the EU and US outfits charge quite a bit extra, we've gotten pretty far by just going to the Chinese board houses directly. Might be worth shopping around once you got the design finished.

[xaxaxa]

Why would a VNA in a plastic box necessarily be worse? If you manage to shield the critical signal paths within the inner layers of the PCB I don't see why you couldn't get an acceptable performance level? Don't expect a $200 unit to perform like a $2000 one. But realistically speaking, do you need it to? There's no need to beat Keysight's FieldFox units I think. But actually, another question: Did you check prices at any other board house? Most of the EU and US outfits charge quite a bit extra, we've gotten pretty far by just going to the Chinese board houses directly. Might be worth shopping around once you got the design finished.

All the sensitive signals are routed as a stripline between two ground planes; the directional coupler balun will have a shield can over it as well.

A vna isn't particularly sensitive to outside interference because the receivers are extremely narrowband (with the exception of those cheap analog phase comparator based ones) and the signal levels involved are fairly high compared to e.g. a spectrum analyzer; in my tests you can even transmit 100mW into the S11 measurement port and not affect measurements much unless your signal coincides with one of the measurement frequency points.

I've looked at all the major pcb fabs and will be using a fairly reputable one from china to ensure quality.

[HalFET]

Sounds very reasonable to me. Additionally if people are so worried about noise they can always line the plastic case with copper or aluminium tape 

Mhhh, Elecrow isn't very cheap in my experience though, or did you switch over to someone different?

[xaxaxa]

Sounds very reasonable to me. Additionally if people are so worried about noise they can always line the plastic case with copper or aluminium tape 

Mhhh, Elecrow isn't very cheap in my experience though, or did you switch over to someone different?

I have a quotation from elecrow but I'm looking into a few other manufacturers as well; I might actually make some test boards to see how good their impedance control is, and then decide.

[krazatchu]

I'm tempted to pull the trigger on the xaVNA two port but the lower end wouldn't cover the 13MHz RFID design I sometimes do.

Any chance we will see an xaVNA two port with a lower bottom range?

Michael

[xaxaxa]

I'm tempted to pull the trigger on the xaVNA two port but the lower end wouldn't cover the 13MHz RFID design I sometimes do.

Any chance we will see an xaVNA two port with a lower bottom range?

Michael

In the far future (several months) I'm planning to develop a "lite" version that covers LF to 150MHz using DDS, since I personally also need to use it for some stuff around 100MHz. It will most likely be T/R or one-port though, and cost less, since the main users of this frequency range are hams and it makes the hardware significantly more complicated to do full two port support. I'll put clock input/output ports to make it possible to lock two of them together to form a two port VNA.