开云体育

On Aug 25, 2023, at 11:18 AM, W0LEV <davearea51a@...> wrote:

?When connected to the PC or laptop, the effective counterpoise is much
longer than when not connected. The counterpoise consists of anything
connected to the measuring unit, including the laptop/PC through the USB
cable. There is nothing wrong with either measurement. You must
electrically remove the "extension" of the counterpoise when connected to
the PC/laptop.

Dave - W?LEV

On Fri, Aug 25, 2023 at 3:05?PM Bob Watson via groups.io <kn4hhptc=
[email protected]> wrote:

I am using a NanoVNA H4 and NanoVNA-App for SWR display. I connected my
end fed half wave antenna to the CNA and compared the two graphical
displays. Both the NanoVNA and H4 displays were set for identical SWR and
frequency ranges (1:1 to 3:1 and 1-30Mhz).
The difference in displays is dramatic (ie 3Mhz. 2.1:1 vs over 3:1 SWR).
Has anyone observed a difference between the H4 and external display
software.

I would appreciate any comments.

Bob, KN4HH

--

*Dave - W?LEV*


--
Dave - W?LEV

QUOTE: Consider this a benefit of the tiny battery powered Nano VNA. A
measurement can be made with minimal impact on the device under test.

Indeed. You hit the nail on squarely on the head. Consider the HP 8753C
with the S-Parameter test set. It weight in around 100+ lbs. I can not
use it with anything that requires a counterpoise or isolation from the
instrument as its too large, sits on a metal shelf, and is connected to the
power grid: a MAJOR increase in any counterpoise. The NANOVNAs allow me
to make measurments that the 8753C really can not make.

However, when one needs to measure at or above our 70-cm band, the size of
the NANOs become significant.

Dave - W?LEV

On Fri, Aug 25, 2023 at 3:50?PM Greg Strickland <greg@...>
wrote:

Last night I was measuring a high Q resonant circuit on the bench with
Nano VNA on battery. The battery was getting low and without physically
moving anything I connected a USB cable from Nano VNA to laptop a few

feet

away. The measurement moved just a bit. Not a cause for concern because
it makes sense. Consider this a benefit of the tiny battery powered Nano
VNA. A measurement can be made with minimal impact on the device under
test.

--

*Dave - W?LEV*


--
Dave - W?LEV

On Aug 25, 2023, at 3:50 PM, Stan Dye <standye@...> wrote:

?If the displays are different while doing a measurement, it is very likely
a calibration issue. Nanovna-app allows you to select the vna calibration
or the app calibration. Make sure that is set to vna to compare traces.
Note that the app receives the same exact s11 data that the nano uses for
display, so if the displays are different, there is a difference in the
calibration or display settings between the two.

On Fri, Aug 25, 2023, 10:42 AM W0LEV <davearea51a@...> wrote:

QUOTE: Consider this a benefit of the tiny battery powered Nano VNA. A
measurement can be made with minimal impact on the device under test.

Indeed. You hit the nail on squarely on the head. Consider the HP 8753C
with the S-Parameter test set. It weight in around 100+ lbs. I can not
use it with anything that requires a counterpoise or isolation from the
instrument as its too large, sits on a metal shelf, and is connected to the
power grid: a MAJOR increase in any counterpoise. The NANOVNAs allow me
to make measurments that the 8753C really can not make.

However, when one needs to measure at or above our 70-cm band, the size of
the NANOs become significant.

Dave - W?LEV

On Fri, Aug 25, 2023 at 3:50?PM Greg Strickland <greg@...>
wrote:

Last night I was measuring a high Q resonant circuit on the bench with
Nano VNA on battery. The battery was getting low and without physically
moving anything I connected a USB cable from Nano VNA to laptop a few

feet

away. The measurement moved just a bit. Not a cause for concern because
it makes sense. Consider this a benefit of the tiny battery powered Nano
VNA. A measurement can be made with minimal impact on the device under
test.

--

*Dave - W?LEV*


--
Dave - W?LEV