开云体育

On Mon, 9 Dec 2019 at 07:56, <erik@...> wrote:

Kurt,

It appears (in my limited understanding) the poor matching to Z0 of CH1
(port 2) is the biggest reason why the T-check is not performing well on
the nanoVNA.

I would not say the matching is poor on port 2. I measured it using my HP
VNA. At least on the NanoVNA sample I have, the return loss on port 2 is
better than the specification on my HP 8720D VNA. I did post some data on
the NanoVNA Facebook group.

I was unable to measure the source match at port 1 well due to the power
coming out of port 1. I had set my HP VNA source power to -20 dBm in an
effort to not cause any non-linearities. Testing at +10 dBm might have been
possible, but I don't know if the results could be trusted. Certainly
switching the NanoVNA off showed excellent match on port 1, and on port 2
is was quite reasonable, and largely independent of whether the unit was
powered on or not.

Erik, PD0EK

Dave