I direct connected my HT whip to the VNA when tuning some "Tiger tail"
ground radials for my HT antenna.
The antenna was a dual-band whip about 15" long, and I swept it attached to
nanoVNA-F which has a metal enclosure. The enclosure is just a little bit
larger than my HT, but results seem to have worked out pretty good.
I set it on edge of a table, but did not notice much of any variation when
grabbing hold of the VNA enclosure with my hand. That might be something to
watch out for if device isn't shielded.
I attached two separate radial wires to a single crimp ring connector under
the HT antenna screwed directly underneath the SMA connector, and then
trimmed one radial for 2m dip in band and the other for 440MHz dip in band.
Signals are now much better with the radials attached to the HT under the
antenna than the antenna alone had.
Maybe this removed the radio from the equation somewhat by providing a
"better alternative" return counterpoise path? I dunno.
I'd think that for adjusting the antenna itself, you could still get close
with it directly attached that way, but adding some tuned radials might
help.
I did notice resonant frequencies changed depending what counterpoise was
attached though, so the antennas may be only approximately tuned (if
they're tuned) assuming an "average" handheld as the counterpoise.
--
--Bryon, NF6M
BryonB