Bob,
I think you are mixing messages but I just purchased the NanoVNA-H-4 with the 4 inch screen. If you're considering another I would get this unit.
Mike N2MS
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On January 20, 2020 at 1:31 PM "Bob Albert via Groups.Io" < bob91343@...
wrote:
Mike,
Thanks for the information.? I did not buy the device because I have a
second nano that does okay.? But after reading your latest suggestion I
guess I'll buy the thing and see if I can upgrade without bricking the
unit.? It should also be a door to future upgrades.? Perhaps I can upgrade
the second nano via its USB port but that unit is flaky and turns itself
off without provocation.? It won't even turn on while the port is
connected, and sometimes even when not connected it fails.? Once on, I can
connect the port.? Then suddenly it behaves properly.
I did have thoughts of replacing the USB connector but it takes ability
that I lack.? I think over a dozen tightly spaced pins and limited access
and tools.
Bob
On Monday, January 20, 2020, 10:13:05 AM PST, n2msqrp < mstangelo@...
wrote:
Bryan,
Thanks. I thought it had to do with the mismatch between the coax and S11
port. I had a length of RG-6 handy and see the same effect with that 75
ohm cable and see the same effect. Since the loss of the Rg-6 is higher
the step responses is decreasing at a faster rate.
I have a 75 to 50 ohm pad. If I have time I may connect the pad to the S11
port, run a calibration using a 75 ohm load and run the test again.
Mike N2MS
Mike,
You need to think about what you are seeing in the time domain.? What the
software produces is the impulse response (the positive going blips) and
the step response (the steps in your plot) of the network attached.? The
steps are the result of multiple trips of a wave traveling through your
cable.? The part you are asking about is the step response of your cable.?
Consider the following.
