[time-nuts] DIY VNA design

Wes wes at triconet.org
Sun Aug 21 10:59:32 EDT 2016

I built an original N2PK, that interfaced via a parallel port.  I did a minor 
upgrade that changed to an improved DAC.  I still have a Win XP laptop with a 
parallel port so can still use it.  Later it was refined to USB but I never 
upgraded, although I still have the unpopulated circuit boards for the later 

The reason for not finishing the project, other than time, is the fact that I 
bought the other ANA under discussion, the VNWA-3.

As someone who started using a grease pencil on the CRT for "calibration" of a 
waveguide reflectometer, graduated to an HP8410 then an HP8510, I never cease to 
be amazed that I can hold something with similar accuracy (albeit less frequency 
range) in the palm of my hand.


On 8/20/2016 11:37 PM, Bob Albert via time-nuts wrote:
> Well that's a start.  Thanks for the link!  I would need more information, as this project goes into areas that are new to me.  And there is no clue as to the cost of construction.
> But I'll study what's there and if nothing else, learn something.
> Bob
>      On Saturday, August 20, 2016 10:46 PM, Orin Eman <orin.eman at gmail.com> wrote:
>   To 60MHz: http://n2pk.com; PCBs available here: http://www.makarov.ca/vna.htm
> To 500MHz, lower dynamic range to 1.3GHz: http://sdr-kits.net/VNWA3_Description.html
> OK, so the latter isn't build it yourself anymore.
> I have version 2.6 of the latter and it works really well to about 575MHz.  Traces can get noisy after about 575MHz.
> Remember these VNAs are only as good as the calibration kit you use with them!
> Orin.
> On Sat, Aug 20, 2016 at 9:46 PM, Bob Albert via time-nuts <time-nuts at febo.com> wrote:
> I was interested in this, but my needs are mostly below 100 MHz.  I wonder what could be done similarly for this lower range...
> Bob
>      On Saturday, August 20, 2016 8:54 PM, Richard (Rick) Karlquist <richard at karlquist.com> wrote:
>   Another great posting, Attila.
> When I was with Agilent, we looked at all kinds of
> simplified network analyzer architectures, and I
> would have to say the author is really well informed.
> One issue he doesn't seem to be aware of is that the
> ADL5801, when driven single ended, has some quirks
> below 100 MHz that I discovered experimentally.
> (The data sheet is silent on this).  IMHO, it
> would be worth 7 Euro's to use a balun, however,
> I would like to know the part number of this
> supposed component.  I am not so sure about MCL
> actually covering 30 MHz to 6 GHz in the same
> balun.  Sometimes their advertising is confusing,
> and when they say .03-6 GHz baluns, they mean
> that the range can be covered in several bands
> by several model numbers.
> Still, quite impressive work by an individual
> practitioner.
> Rick
> On 8/20/2016 7:19 PM, Attila Kinali wrote:
>> Moin,
>> I stumbled over a new open hardware/source VNA design:
>> http://hforsten.com/cheap- homemade-30-mhz-6-ghz-vector- network-analyzer.html
>> Unlike other designs out there, this one is very well done and has very
>> little room for improvement, without increasing the price considerably.
>> About the only things i would do different is to use two receiver
>> channels, one fix connected at the TX source to be able to do a
>> difference measurement between TX and the RX channels and thus
>> improving precision. And the other would be to use a dual ADC
>> with an FPGA for the data processing, again in order to increase
>> performance.
>> But as I wrote, both changes would increase complexity and price.
>> Other than being a well thought through design, the website also
>> explains all the big design choices and why this or that has been
>> done instead of one of the many alternatives. That alone makes it
>> worth reading, IMHO.
>>              Attila Kinali

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