On Wed, 2 Oct 2019 at 04:52, mike watts via Groups.Io <wy6k=
[email protected]> wrote:
Some readers of my Tips for New Users document pointed out that there was
some ambiguity about the type of SMA adapter that should be installed onto
the calibration standards. It depends upon whether or not you intend to
use coax jumpers to connect the DUT to the VNA. If you use jumpers, the
adapters should be female SMA to female SMA. If you like to attach the DUT
directly to the VNA, then the adapters for the calibration standards should
be female SMA to male SMA.
I have attempted to clear up the issue, and have included some pictures to
illustrate the options.
Thanks,
Mike WY6K
If you add a female-female adapter onto the supplied short you will really
mess up its properties. The short supplied has a *very* small negative
delay. As far as I am aware, that¡¯s not accounted for in the firmware, but
it really is so small to be of little practical significance. If you then
and a female-female adapter onto the short standard, it will introduce a
one-way delay of about 42 os, or two-way delay of around 84 ps. (The exact
amount depends on the adapter.) That will add a significant error, which
can not currently be compensated for in the firmware.
Additionally, you will get more stable results if you don¡¯t use cables. ALL
cables will introduce some amplitude and phase instability as they are
flexed or their temperature changes.
I would suggest that you advise people to put m-f adapters on the NanoVNA.
The delay of such adapters will be a but longer, but the calibration should
remove that.
I really can¡¯t see how your advice is good.
Dave.
--
Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...
Telephone 01621-680100./ +44 1621 680100
Registered in England & Wales, company number 08914892.
Registered office:
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