I agree that it leads to a different measurement. My claim is that it leads
to a more accurate measurement than using the supplied "open", since the
software does not compensate for the characteristics supplied open, but
rather assumes a near-perfect open.
The fully characterized cal kit I recently received also uses an open
connector (with suitable compensation values) as open, not an SMA cap like
supplied with the NanoVNA.
--
Rune / 5Q5R
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On Wed, 18 Sep 2019 at 12:13, <qrp.ddc@...> wrote:
[Edited Message Follows]
Rune Broberg, the problem with "nothing connected to CH0" case is that it
has different geometry configuration than usual SMA connector. It leads to
different capacitance and inductance than usual SMA connector and also
leads to different delay line, which leads to incorrect measurement. But it
depends on what you needs. If you're work in 1-30 MHz range, you may keep
"nothing connected to CH0" it will not affect result much. But if you want
to use frequencies above 30 MHz, you're needs to use proper open terminator.
