What I understand Nano Vnas cannot directly measure all S-parameters. Like S22 and feedback from output to input. Are there coaxial switches which could swap two NanoVna ports/channels?
Too bad there are no GPIOs to handle external devices.

On 3/29/23 8:06 AM, Leif M wrote:
> What I understand Nano Vnas cannot directly measure all S-parameters.
> Like S22 and feedback from output to input. Are there coaxial switches
> which could swap two NanoVna ports/channels?
> Too bad there are no GPIOs to handle external devices.

What you want is known as a Coax Transfer Switch - they're available
surplus for <$100 (sometimes a lot less).
Yes,it would be nice to have GPIOs, but the surplus switches are often
24V, so you need some drive electronics. And since the firmware doesn't
do both measurements, you're running from a computer and it's easy to
find a USB to relay control box of some sort.

I think that Joe Smith’s software has provisions for controlling an
external transfer switch.

On Wed, Mar 29, 2023 at 9:41 PM Jim Lux <jimlux@earthlink.net> wrote:

> On 3/29/23 8:06 AM, Leif M wrote:
> > What I understand Nano Vnas cannot directly measure all S-parameters.
> > Like S22 and feedback from output to input. Are there coaxial switches
> > which could swap two NanoVna ports/channels?
> > Too bad there are no GPIOs to handle external devices.
>
> What you want is known as a Coax Transfer Switch - they're available
> surplus for <$100 (sometimes a lot less).
> Yes,it would be nice to have GPIOs, but the surplus switches are often
> 24V, so you need some drive electronics. And since the firmware doesn't
> do both measurements, you're running from a computer and it's easy to
> find a USB to relay control box of some sort.
>
>
>
>
>
>
>

On Wed, Mar 29, 2023 at 09:00 AM, Leif M wrote:

>
> Are there coaxial switches which could swap two NanoVna ports/channels?

As Jim Lux mentioned, what you want is a transfer switch.  There are a lot of places you can buy them, new and used.  New prices are generally outrageous.  There is a gentleman named Lothar who parts out microwave gear and often announces what he has available on the North Texas Microwave Society groups.io and maybe some of the other groups who often has good deals on used but tested microwave relays.  I have bought from him several times and been satisfied with my purchases.  I have seen transfer switches on ebay also, but make sure you know what you are buying if you buy on ebay.  A relay with 3 SMA connectors is not a transfer switch.  Neither is a box with a knob on the front of it and 2 BNC connectors on the back of it.  You will find both being sold as transfer switches on ebay.  Let the buyer beware.

Why not simply measure then reverse the DUT and measure again? A transfer
switch is needed if you are building an automatic test system, but you do
lose a bit of dynamic range and accuracy when calibrating through an
external transfer switch.

On Thu, Mar 30, 2023 at 11:31 PM Jim Allyn - N7JA <jim@allynelectronics.com>
wrote:

> On Wed, Mar 29, 2023 at 09:00 AM, Leif M wrote:
>
> Are there coaxial switches which could swap two NanoVna ports/channels?
>
> As Jim Lux mentioned, what you want is a transfer switch. There are a lot
> of places you can buy them, new and used. New prices are generally
> outrageous. There is a gentleman named Lothar who parts out microwave gear
> and often announces what he has available on the North Texas Microwave
> Society groups.io and maybe some of the other groups who often has good
> deals on used but tested microwave relays. I have bought from him several
> times and been satisfied with my purchases. I have seen transfer switches
> on ebay also, but make sure you know what you are buying if you buy on
> ebay. A relay with 3 SMA connectors is not a transfer switch. Neither is
> a box with a knob on the front of it and 2 BNC connectors on the back of
> it. You will find both being sold as transfer switches on ebay. Let the
> buyer beware.
>
>
>

I am building the cabling for one right now.  My fingers get worn out from switching between highpass and lowpass and moving a termination to the unused port.  My application is usually for tuning vhf/uhf  filters and I am hoping that the repeatability and accuracy is good enough.  I will know soon

I am in the process of building the cabling for a variation of that.  My application is usually vhf/uhf duplexers/filters and my fingers just cant handle much switching between lowpass and highpass as well as moving a termination to the unused port.  Transfer switch does that nicely. Hopefully, the accuracy and repeatablity doesnt suffer too much.  I will know soon