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Hi John, Mike,

Several folks have done various measurements including myself.
Measurements and records between big box VNA and the nanoVNA would be of
interest. However, that said, my best guess is that the agreement below a
few hundred MHz will be excellent. For the most part that is what I have
found although I did not bother with making recordings of the sweeps
between instruments. I expect as you approach 900 MHz that the deviation
between measured on big box vna and the nanoVNA will be larger. The simple
fact is due to the accuracy and records stored for the calibration pieces.
The SMA short, open and 50 ohm load, I SUSPECT are treated as ideal
elements. They are certainly not ideal. I am in the process of finding out
from the developer how these calibration pieces are handled. Regards, Alan

Hi Mike,

Here is a 3 pole helical filter centered at 465 MHz. The filter is "C"
coupled so the skirt on the high side rolls more gentle than low side. The
insertion loss and return loss as well center freq are pretty spot on with
expected. The DR on the second pix shows we can see down at least 65 dB and
if I set the reference point to the screen top, perhaps 70 dB. Next, I'll
try the big box. I expect very similar results although if I were to read
the R+jX values at each and every frequency point there will be delta
values. Alan

Hi Alan

You've obviously got a good one there. I have been finding odd calibration
issues and finally worked out it mine is happier up to 450 MHz and not
going too low either, although the issue may be the span rather than the
frequencies. I currently have it set to 1.5 to 450 MHz and am seeing
repeatable results.

I was able to quickly compare mine with a MiniVNA Pro (which works up to
200 MHz) earlier - another budget VNA that costs GBP 380. I wasn't able to
capture screen shots but on the couple of things we tried the results
looked fairly close.

I've attached a photo showing what mine thinks of a dual band handheld
antenna, which looks plausible.

73

Mike


On Sat, 20 Jul 2019, 16:28 alan victor, <avictor73@...> wrote:

Hi Mike,

Here is a 3 pole helical filter centered at 465 MHz. The filter is "C"
coupled so the skirt on the high side rolls more gentle than low side. The
insertion loss and return loss as well center freq are pretty spot on with
expected. The DR on the second pix shows we can see down at least 65 dB and
if I set the reference point to the screen top, perhaps 70 dB. Next, I'll
try the big box. I expect very similar results although if I were to read
the R+jX values at each and every frequency point there will be delta
values. Alan

Is the 4 trace a firmware thing, or hardware thing
Frank

On 7/20/2019 1:49 PM, Mike Brown wrote:

Hi Alan

You've obviously got a good one there. I have been finding odd calibration
issues and finally worked out it mine is happier up to 450 MHz and not
going too low either, although the issue may be the span rather than the
frequencies. I currently have it set to 1.5 to 450 MHz and am seeing
repeatable results.

I was able to quickly compare mine with a MiniVNA Pro (which works up to
200 MHz) earlier - another budget VNA that costs GBP 380. I wasn't able to
capture screen shots but on the couple of things we tried the results
looked fairly close.

I've attached a photo showing what mine thinks of a dual band handheld
antenna, which looks plausible.

73

Mike


On Sat, 20 Jul 2019, 16:28 alan victor, <avictor73@...> wrote:

Hi Mike,

Here is a 3 pole helical filter centered at 465 MHz. The filter is "C"
coupled so the skirt on the high side rolls more gentle than low side. The
insertion loss and return loss as well center freq are pretty spot on with
expected. The DR on the second pix shows we can see down at least 65 dB and
if I set the reference point to the screen top, perhaps 70 dB. Next, I'll
try the big box. I expect very similar results although if I were to read
the R+jX values at each and every frequency point there will be delta
values. Alan