This is one of the big advantages of a small, self contained, unit. One
can connect it to a balanced load or coax with little influence from
surroundings ofr connection to a power source. During CAL. and making the
measurement, let the NANOVNA dangle, do not hold on to it as your body will
introduce variables. If you are measuring at HF frequencies, especially on
our lower bands, the introduction of a very small instrument intelligently
connected to the open wire line will have negligible impact on your
ultimate measurements.
To form the connection between the VNA and the open wire transmission, I'd
first find just the right size bare tinned wire that will snugly fit the
center of the s11 SMA connector (CH 0). Then,, make yourself two *very
short* clip leads using the small alligator clips. Clip the wire to one
end of one clip and run the other between the SMA backshell and one side of
your open wire line. Clip the other clip lead that holds the wire in the
center of the SMA connector to the other side of the open wire line. Make
your measurement. Be sure in both calibration and making the measurement
to NOT HOLD the VNA.
Measurements at HF are reasonably accurate with this method. 6-Meters on
upward, not quite so....
Dave - W?LEV
On Sat, Dec 28, 2019 at 1:19 PM entilleser via Groups.Io <entilleser=
[email protected]> wrote:
How would you do it?
I'm thinking that first, I'd need to construct an adapter for the VNA -
sma connector, short length of coax, with clips on the center conductor and
shield to clip to the two sides of the ladder line (but, the quality of the
connection between the clips and the ladder line wires (among other things)
is going to introduce variables, right?)
Second, I should calibrate for the desired frequency range using the
adapter as described above, in order to "calibrate out" as much of the
peculiarities of the measurement system as I can - I would clip my adapter
to my QRP-Labs dummy load for the load part, leave the clips dangling for
the open, and clip them together for the through.
What kind of trouble am I going to be getting myself into?
--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
