开云体育

If i correct understand problem in loaded from NanoVNA start/stop range?

NanoVNA Saver not correct do this if not detect VNA:
Here this code:
def _get_running_frequencies(self):
'''
If possible, read frequencies already runnung
if not return default values
Overwrite in specific HW
'''
return 27000000, 30000000

This function not defined for H4 ?:
def _get_running_frequencies(self):

if self.name == "NanoVNA":
logger.debug("Reading values: frequencies")
try:
frequencies = super().readValues("frequencies")
return frequencies[0], frequencies[-1]
except Exception as e:
logger.warning("%s reading frequencies", e)
logger.info("falling back to generic")
else:
logger.debug("Name %s, fallback to generic", self.name)

return VNA._get_running_frequencies(self)

Original NanoVNA 2.8" screen

Linux Mint 19.3
Python 3.7.5
NanoVNA Saver 0.3.9

When NanoVNA Saver connects to device Sweep Range always defaults to 27 -
30MHz.
After manually setting Sweep Range 1 - 100MHz NanoVNA Saver behaves
normally.

Sweep Range does not appear to be stored in
~/.config/NanoVNASaver/NanoVNASaver.ini.

Using putty

ch> clearconfig 1234

Recalibrated device and NanoVNA Saver. No change.

Flashed problem
disappears.
Reflashed
problem returns.

Problem does not occur when SimSmith 18.3 is used to connect to
NanoVNA+hugen79 1.0.45

Any ideas please?

Original NanoVNA 2.8" screen

Linux Mint 19.3
Python 3.7.5
NanoVNA Saver 0.3.9

When NanoVNA Saver connects to device Sweep Range always defaults to 27 - 30MHz.
After manually setting Sweep Range 1 - 100MHz NanoVNA Saver behaves normally.

Sweep Range does not appear to be stored in ~/.config/NanoVNASaver/NanoVNASaver.ini.

Using putty

ch> clearconfig 1234

Recalibrated device and NanoVNA Saver. No change.

Flashed problem disappears.
Reflashed problem returns.

Problem does not occur when SimSmith 18.3 is used to connect to NanoVNA+hugen79 1.0.45

Any ideas please?

David, I have been following this thread and thought I might add something
that might help you. This link that I have attached should give you an
easy way of making your Short/Open/Load standards using SO-239 connectors.

Fred - N4CLA



On Fri, Jul 16, 2021 at 12:12 PM David Kozinn, K2DBK <dkozinn@...>
wrote:

Thanks for all the replies. It sounds like for the frequencies I'm

looking

at, there won't be much of a difference no matter which method I use.

@Lou W7HV: Could you point me to where I could pick one a low-power 50

ohm

PL-259 as you mentioned? I looked and all I've found so far were dummy
loads with a minimum rating for 10W, which is way more than what's needed
for me. Same with looking for resistors, except for industrial supply
places where I could get a resistor for $0.50 plus $7.00 shipping.

73,
David, K2DBK

HELLO ALL

As of July 16th:

I gave the Nano VNA talk in two installments to the Leicester Radio
Society (UK) but I did not record it and I did not post it. I'll contact
the person who did post it and see what happened to it.

I only reference this (recorded) video as the latest talk I have given on
the Nano VNA

Part I was the basic stuff - very low math but I do mention Smith Chart
I treat the nano VNA as just another tool in your ham radio toolkit
I show how you can use the Nano VNA to check out coax, filters, and
antennas.
All of the graphs were produced by NANO VNA SAVER software (free,
Win 10).
THANK YOU to the author of that app.

Part II Uner the Hood - looks at all of the measurements and calculated
parameters in more detail.
You can Calibrate the Nano VNA via software (Nano VNA SAVER) and do a
lot more with the tool.
I then go into gory detail about the Smith Chart - but not assuming
one is already familiar with it.
Part II ends with looking at resistance, reactance, and impedance and
how these plot on Smith Charts.
How do antenna tuners "cancel" the reactance on your feedline by
introducig a CONJUGATE match?
There is a bit of magic and fancy math, but I try to avoid that.
Warning: there is a Smith Chart quiz in the talk and in the PDF.

Conclusion: antennas do not "need to be resonant" to work well
(i.e. 43 ft vertical) but the entire antenna system (including feed line)
needs to present a reasonable load to your rig. The typical SWR meter gives
you a reading (2:1) but gives no information as to what you can do to
improve your antenna.

Thus, the Nano VNA is a much better "tool" at analyzing your antenna than
a mere SWR meter.

This is the best I've been able to do and explain (as a non-engineer)
after one year experience with VNA.

If I can get it posted again, feel free to share both the video and the
extended PDF with others.

This has been and continues to be a learning challenge for me.
There are many ways to "see" a concept. I'm looking for a 9th grade level
right now.
I hope my video Zoom and the PDF is aiming at the right audience.

73
K3EUI Barry
Philadelphia
K3euibarry@...

The need for calibration and how frequently, varies with the measurement. If you need great precision, like accurately measuring a 40-db return loss, you might need to carefully calibrate several times a day. If you only need to know the frequency of an S11 dip, like tuning a small loop antenna in the field where there is only a single adjustment, you don't even need to calibrate at all.
73, Don N2VGU