Sam Reaves 2023/12/02 22:57
Hi Joe,
I suggest a sanity check first.
Set the unit to sweep the full band 50KHz to 900MHz
Initiate a calibration sequence.
Run through the Open, Short, Load calibration with the cal kit supplied
with the NanoVNA. Set the unit to display the Smith chart and verify that
with the open the dot is to the far right, the short it's to the far left
and 50 ohms should be dead center in the chart. If you turn on the yellow
trace and set it to SWR with the open or the short, the unit should display
a very high SWR and with the 50 ohm load it should be 1:1.
If that works the unit is operational. If not you have either not done the
calibration correctly or you have a bad cal kit or you have a defective
NanoVNA. The Cal kit Short and Load can be verified with a DMM. Typically
the load has a silver colored nut on the SMA connector. The open is
obvious, it has no pin. The short when you look at it is obvious as well.
Assuming that it passes, narrow the frequency range to the range of
interest. For example if you are in the 40 meter band set the frequency so
that it covers 6.5MHz to 7.5MHz. You want to set the start and stop
frequency so that it is close to the center of the band. Re-run the
calibration so that it will cover the change in frequency span.
As above check the calibration with the open/short/load on the smith chart.
The readings should be the same as before. Open far right, Short far left
and load dead center. Note that if you change the start and stop
frequencies you should always redo the calibration for best results.
Now before connecting your antenna ground connect a temporary short between
the coax center conductor and the shield ground to discharge any static.
This step is necessary to keep static discharge from damaging the front end
of the NanoVNA. Note also that you should never be transmitting on any band
(even on another antenna) with the NanoVNA connected to an antenna as the
RF input to the NanoVNA is broadband and will not tolerate large signal
levels without damage. It is also not recommended to leave the NanoVNA (or
spectrum analyzer for that matter) connected to an antenna when not in use.
That should get you started.
73,
Sam
Sam Reaves
ARS W3OHM
Owner / Moderator of:
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Staff Scientist Andritz Rolls Global Research Center (RETIRED)
On Sat, Dec 2, 2023 at 10:29 PM Joe in Missouri <joe@tittiger.com> wrote:
> What a frustrating as Hades experience this has been....
> Anyhow I can not get SWR to display anywhere on the screen.
> I have watched a handful of YouTubes and do exactly as instructed but no
> SWR is
> on the screen anywhere at all!
>
> Thanks in advance
>
>
>