VNA-nuts ? Show your VNA

[PA4TIM]

I'm a bit VNA addicted. I have 3 of them. One I build a few years ago as a kit, the VNWA from SDR-kits. a 0-1300 MHz digital vna/lcr meter/ SA/ signal generator/counter/powermeter. But there are people who run it over 2GHz. And one user I know, uses some simpe extra HW to get over 10GHz. The software has that option so that makes it easy. The second I have is a newer version from the kit and came ready for use. The first is build in a 19"cabinet and in my lab, the second I have build in a shielded old RF amp housing together with a PSU. Together with all accesoiresand laptop  it fits in a small suitcase.

I also wrote a series of tutorials for newby's VNA-nuts.
The 3rd one is the grandfather of VNA's. The HPO-8704+8601 1-110 MHz VNA. I have the CRT and analog dB meter plugin.

The vnwa, small but very capable In the link more pictures and on an other page of my side there are pictures from building it
http://www.pa4tim.nl/?p=1546 (in Dutch but there are pictures for the monolingual.

http://www.pa4tim.nl/?p=676 The portable one, pictures of accesoires, suitcase etc (in English)

http://www.pa4tim.nl/?p=1594 My tutorials (in English, some also in German and French.

http://www.pa4tim.nl/?p=646 the HP-8407 made in 1968.

[DonRon]

I have the minivna plus from miniradiosoliutions. Very nice and small - use it mainly to check antennas.
Great to use via bluetooth in combination with an android-tablet and the android-app bluevna from YO3GGX.

[PA4TIM]

A friend of my has the miniVNA, that is also a very nice vna. We have tested it here because he was curious how good it was and that was very usable. Like you he uses it only for antennas.
I know some users of the VNWA also use it remote via Wifi (if I remember well) but I do not know how. I have used mine once as a test through  vnc but for my use that is not handy. I use it for the strangest things but not often on antennas. My dipole is 50 meters and static allready killed a transceiver so if I measure it I use the HP with a 40 dB directional coupler and 100 K bleeders.

I also like to read about network analyses. I have the books from Hiebel (R&S) and Joel Dunsmore (HP) My first book that made me interested in network analyses was the book from Hans Nussbaum about the Funkamateur analyser. I wanted to buy that because my Russion SNA died beyoind repair (and believe me, I have tried, and I had some wobbulators too)
But just at that time a usb interface for the VNWA was anounced. I liked it allready but I had no PC with parallel port (only laptops)
So I ordered a kit that was delivered 1 day befor my holyday .

[DonRon]

I bought that book "HF-Messungen mit dem Netzwerktester" from Hans Nussbaum at the last year ham meeting in weinheim. Even if he relates to the FA network analyzer in this book it is from great value for me - I wanna learn more about measuring coils and capacitors, LC-circuits .... And this is well written in this book for a newby like me.
I wanted to buy the Funkamateur kit - but I waited too long. They are sold out and they will not offer the kit any longer.

Concerning BOOKS:
I too have the book from R&S and several App Notes from HP/Agilent.

Greet's
Ronald

[KJDS]

My 6GHz HP8753C. It's a little worn but works well enough. At some stage I'll upgrade it to an ES.

[Jay_Diddy_B]

Hi,

I ONLY have two, does that qualify me for this thread? 

I have an HP8753C the 3 GHz version with an 8502A T/R test set.

I also have 3577A with both S-parameter test sets 50 Ohms and 75 Ohms. 35667A and 35667B

Regards,

Jay_Diddy_B

[DL8RI]

A VNA is still on my wishlist... (numer one )

Right now I use a R&S ESVP and a HP 8502A Opt H26 for transmission/reflection. But maybe I go for the SDR-Kits this year until I get a real one (R&S ZVRE or somthing of that caliber).

[G0HZU]

I have an old HP8714B 3GHz VNA. It's only a T/R VNA but I've developed a method to get good 2 port s parameter data from it. However, this involves mucho swapping of connections and use of attenuators for the S21 and S12 measurements.
I get the raw vector data via GPIB and then gradually build up a 2 port s parameter file for S11, S21, S12, S22. I've also created my own user cal files for it to enhance the accuracy when taking 2 port data.

It takes a few minutes to do it all.

It has the biggest/nicest smith chart display of any VNA I've used but I do want to upgrade it to something like a 6GHz 8753ES. I will miss the nice display of the 8714B when I upgrade and I've been using it for so many years (at work and now here at home) that I've grown quite attached to it

I have also recently bought an old HP8405A vector voltmeter and I sometimes also use a simple 2 channel scope and a sense resistor or a coupler to make vector measurements with a scope.

I'm playing around with negative impedances at the moment eg negative capacitor and negative resistor circuits and the  HP8405A VVM is an ideal tool for this

[Mr Simpleton]

Have the VNWA v 2.3 and love it. Almost finnished the N2PK v4.3 just need attach power and start debugging the PCB's and the I do have the HP 85046A S-parameter testset for HP 8753A/B... still would love to have the whole machine though. Daytime I do use the HP 8753ES...

[nctnico]

Its a pity the SDR-kits website is such an uncomprehensible pile of words. I tried to look for the kit, a simple explaination on how to use it or specs but they don't seem to exist. If it can be tricked into going over 3GHz at reasonable sweep speeds I might consider buying one. I just have to get my head around to read those Smith charts.

[Mr Simpleton]

The VNWA is not offered as a kit anymore...
Just had a look at the SDR Kit webpage and it's not that bad, really 
There are a number of links to external sites offering documents, including one from PA4TIM

Now, some have been able to run the VNWA above the 1.3GHz, but the dynamic range will suffer. If you do have to make serious measurements on 2-3 GHz this instrument may not be the best for you!

[DonRon]

concerning SDR-Kit VNWA:

http://sdr-kits.net/VNWA3_Description.html

u will find some infos - also u can download the Help-File (pdf) and the software to check

There is a yahoo-group too:

http://groups.yahoo.com/neo/groups/VNWA/info

But I think it is not possible to work up to 3 GHz. It is specified up to 1.3 GHz with limited dynamic range, so going > 1.3 GHz performance will decrease extremely.

[PA4TIM]

It is remarkable that many VNA-nuts also work with a vna professional.

The VNWA is indeed not as kit for sale. I think the last kit was 2 years ago. When the sales increased Jan could not make enough kits for the demand. I build two kits and they were very complete. All smd parts color coded by Jan and strips cut to the right number. That must be a hell of a job. And Tom spend so much time in supporting the builder problems that the software development went a bit slow. After the kits stopped the number of software updates and new functions increased.

I have never used a modern Agilent or R&S (I have not even seen on in real) But I am very curious to how they work. But I think the digital ones are far out of my league and the VNWA does everything and more as I need. But the 3GHz the
HP's mentioned here is a very nice and usable bandwidht for the higher HAM bands. My first VNA was the HP. A friend bought a 8405 for 25 euro and got the 8407 for the same money. He did not wanted it but I did. But I had no clue about VNA's other then the fact that they are cool and can  do more things as my wobbulators. But the first drawback was that it was just part of a setup. I needed a display, cables, calkit and a sweeper. I found a dead 8601 sweeper for 100 euro (the seller told me it was perfect working) and later I found a second 8407 with a display. It should be in working condition but the attenuators missed some parts so I save iot as a parts mill vor my working version.

Today I made a GR call kit. I allready had an Original GR load and now I made a short and open. The GR connector is briljant for VNA user. No male/female calkit, no portextentions for a tru.
When I got the russian analyser it took me weeks to get useable results because nobody told me I need a diodedetector.

[Po6ept]

I recently picked up an unbuilt N2PK VNA kit and am wondering if it is worth building because it has a parallel port interface.  Does anyone have one?  If so, does it work well?

[Mr Simpleton]

The N2PK is extrememly powerful, and if you only have to measure up to 60 MHz the dynamic range goes up to roughly 120 dB! You may be able to find a supplier for a USB to parallell too. I am almost certain you can get one of those cheap logic analyzers (i.e. Saleae knock-offs at $10) and use these. Same chips and you may only to have to program an EE-Prom to get it operative. I am about to put my N2PK in operation, it has been assembled for a number of years but never got round to start using it (for a number of reasons, not for missing performance though)

When you say unbuilt kit, you should really think about getting the latest PCB i.e. version 5.2 (www.makarov.ca), mostly uses the same components, but refined design. You will have two detectors which speed up measuring and make sure you use the newer A/D as they are vastly faster the the old ones! You need to tell us more what is included in your unbuilt kit.

[Rufus]

I also own an SDR VNWA - no point showing it you know what it looks like.

[G0HZU]

It would be nice to see some critical side by side comparison tests of these mini VNAs against a classic HP/Agilent VNA.
I did find a few quick comparisons online but they all seem a bit crude and clumsy and some tests make even the HP VNAs look poor (obviously they are not poor).

Has anyone here done a direct and critical comparison?

[Po6ept]

...You need to tell us more what is included in your unbuilt kit.

The kit was shipped March 2011.  I have the board shown at this web site but he doesn't mention the version: http://www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/N2PKVNA/BoardsAndParts.htm

It's kind of hard to figure out exactly what I have but there are a lot of parts in the bag.  There is no ADC in the kit so I can elect to buy the LTC2440 instead of the LTC2410.  I do have the 148.344 MHz oscillator module, so I don't need to find a substitute for that part.  There is no T1-6T reflection bridge board in there. 

[Mr Simpleton]

Had a quick look at the W8WWV page, and it looks pretty much as the original N2PK pcb layout... but with the improvements added.
Still it depends on what you want, I would rather save up for the makarov.ca pcb set which is what most people do use now.
Still, I am sure you will be able to put it all together! It is a marvellous thingy 

BTW It seems your kit is a carbon copy of the N2PK by looking at this page: http://www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/N2PKVNA/Kits.htm

[Rufus]

It would be nice to see some critical side by side comparison tests of these mini VNAs against a classic HP/Agilent VNA.

You could read SP4SKR's comment here http://www.eham.net/reviews/detail/10893 on the SDR Kits/DG8SAQ VNWA.

VNAs have the property that you can obtain very precise results with very little in the way of precision circuitry. It is mostly down to calibration. People spending a few hundred on a VNWA are not going to spend a few thousand on a cal kit. The cheap VNWA's calibration will likely drift more and be less repeatable. The dynamic range is limited especially above 400MHz (or whatever) because it is running on spuria from a DDS generator. The 'dirty' excitation means it may not play well with non-linear or active devices.

Of course they are not going to be as good as the 'real thing' but they really are very capable at a small fraction of the price. I love the way they manage to get so much out of cheap circuitry by being clever.

[Po6ept]

Had a quick look at the W8WWV page, and it looks pretty much as the original N2PK pcb layout... but with the improvements added.
Still it depends on what you want, I would rather save up for the makarov.ca pcb set which is what most people do use now.
Still, I am sure you will be able to put it all together! It is a marvellous thingy 

BTW It seems your kit is a carbon copy of the N2PK by looking at this page: http://www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/N2PKVNA/Kits.htm

Thanks for letting me know about the makarov.ca boards.  I would much rather build the dual detector one with a USB interface instead of the parallel port.  The PC boards are a small part of the overall cost and at $36 are a bargain. 

This is one of the reasons I enjoy this forum so much.  No matter how unusual the project, someone on here knows about it and is willing to share what they know.  I appreciate the help, Mr Simpleton.

[G0HZU]

You could read SP4SKR's comment here http://www.eham.net/reviews/detail/10893 on the SDR Kits/DG8SAQ VNWA.

It's a very positive review but I was kind of hoping to also see some critical test data. None of the test data I've seen seems to have much in the way of control so you end up not knowing the limits of each instrument.

I mostly use my VNA (and the ones at work) for generating n port models of components or small circuits to allow me to simulate as accurately as possible on a PC. So the accuracy of vector based measurements is very important to me.

I like the fact the VNWA3 goes down to 1kHz and obviously it is also very portable. But it's really frustrating that nobody on the planet seems to review these mini VNAs critically. You get a few half baked and poorly controlled tests that don't really stretch any of the instruments and (to me) they just demonstrate the limits and flaws of the test procedure rather than any of the VNAs on test.

[Rufus]

It's a very positive review but I was kind of hoping to also see some critical test data.

You could join the yahoo group (if you can - yahoo changes made such a mess I couldn't log on any more so gave up and haven't been there for ages). There are a lot of files in the group I think I remember some comparison plots. The best place to make enquires about the SDR Kits version anyway.

[G0HZU]

OK thanks, I'll have a look at the yahoo group tomorrow.

I have to agree that yahoo groups are generally not very well organised and I have had similar problems as yourself with other yahoo groups but I'll give it a try

[PA4TIM]

The vnwa, when calibrated carefull and the right way gets a very good result on the R&S T-check. Some members of the yahoo group have tested it against professional VNA's and it scores very good. It gives very good results upto 800-1000 MHz, above that it is usable but in that case you need a very good documented calkit. My kit is usable upto 1300, my V3 gives usable results upto 1500 MHz.

But even if it does not performs as good as a >10k or > 100k  analizer it is still a real bang for bucks and not in the way that counts for the cheap scopes and meters. (low performance/low price)

I do not get notifications for my own topic ??