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Re: V2 Design #nanovna-v2

 

Re: edy555 release 0.7.0-20200223 #firmware

 

Hello,

If one uses *nanovnasaver*, what do you think it will be the best firmware?

I am fortunate to have a small PC at my desk to use with the VNA.




*73 de Lu¨ªs, CT2FZI*





<>

On Mon, 16 Mar 2020 at 21:59, hwalker <herbwalker2476@...> wrote:

Hot on the heels of his beta 0.8 firmware release for the NanoVNA,
DiSlord has followed it up with an additional beta firmware release which
adds user selectable averaging via a "DISPLAY->BANDWIDTH" menu. Bandwidth
can be set to 1 kHz, 300 Hz, 100 Hz, 30 Hz or 10 Hz. As any who has used a
commercial VNA can tell you, using averaging can smooth out your data but
at the expense of sl-o-o-owing down sweep rates. Truly no such thing as a
free lunch.

Latest beta is located at
.
This is a preview of where the next edy555 firmware release is headed.

I thought there were no more tricks in the firmware developers bags to
add more features to the limited flash space of the NanoVNA-H. That was t
the main reason I begin gravitating towards the NanoVNA-H4 and NanoVNA-F.
DiSLord's re-write and optimization of the NanoVNA's firmware, shows the
NanoVNA-H is not quite ready to relinquish its crown. Looks like the -H4
and -F will be behind the curve until the upcoming edy555 firmware releases
are ported to them.

Per DiSLord:
"When you drop below 1kHz, the scanning speed is significantly
reduced, and the responsiveness of the menu drops, but is generally
workable."

Also as previously noted, this beta firmware release is not for the
NanoVNA-H4 or NanoVNA-F.

- Herb
Re: can't make a Thru calibration? #calibration

 

clearconfig 1234 did not seem to help

To calibrate I:
Connect open to CH0, OPEN
Connect short to CH0, SHORT
Connect 50 ohms load to CH0, LOAD
Remove 50 ohms load from CH0 and connect to CH1, ISOLN
Connect CH0 to CH1, THRU

I tried both connecting the loads directly to the VNA, and through male-male cables with female-female adaptors in the ends (then remove one of the adaptors to perform THRU).
Re: Wich one the get ? nanoVNA F or H4

 

In fact this issue is not a big deal to fix it by adding washer. However, it would be frustrated when happens. I did encounter the issue with my 2.8 inch H version so that I simply go back without the enclosure.

VR2XHQ

On Mon, Mar 16, 2020 at 08:53 AM, Larry Rothman wrote:


Yup, the issue with the plastic housing is a 'potenial' problem but almost all
H4 units are just fine.?



On Sun, 15 Mar 2020 at 8:14 PM, Ben Yuen<benyuenkc@...> wrote: I
have 2.8 and 4.3 inch version. They can do TDR with updated firmware.?
Personally I would prefer the F version with metal case which is free from the
potential problem of "plastic case" issue at this moment.

VR2XHQ



IMG_20200302_115421.jpg

Re: Analysing Input Impedance Matching Circuit for the NE602

 

Kerr,

I don't how you are winding or measuring these transformers but something is definitely not right. The coefficient of coupling K is very close to 1 with binocular cores and the core losses are not very high. You should only have a dB or so of insertion loss as I showed you in the W8JI link and from my own measurements. I assume you are using insulated wire or you will get shorted turns due to Mix 73 low resistivity.

Possible errors:
- Winding wrong way. 1 turn is going through one hole and back through the other
- Not using insulated wire
- S21 not set up correctly on your nanoVNA

Does your S21 read close to 0 dB when CH0 is connected to CH1 with the SMA cables?

Take a picture of your setup and maybe we can help.

Roger
Re: Analysing Input Impedance Matching Circuit for the NE602

 

On Tue, Mar 17, 2020 at 12:21 PM, David Eckhardt wrote:

Physically, yes. Circuit-wise and considering magnetics, its is a full
turn.
I have never heard of anyone counting a pass through one hole of a binocular core as a full turn. Fair-rite states:

"The 61 and 67 material multi-hole beads are tested for AL value. The test frequency is 10 kHz at < 10 gauss. The test winding is five turns wound through both holes."

Note: both holes.

TDK says:

"Magnetic characteristics and AL value are based on winding of center leg."

A winding around the center leg is a winding through both holes.

If you look at the graphic posted in post number 11791,you will see that it says:

"2 passes = one turn" and "6 passes = 3 turns"

and the graphic illustrates that.

You can count turns any way you like, but if you want to use the manufacturer's data, or anybody's instructions for winding a certain inductance value, then one turn is a pass through both holes. A pass through one hole of a binocular core is a half turn.
Re: Analysing Input Impedance Matching Circuit for the NE602

 

So, the good match is likely mostly due to loss. Of course, since you have
two transformers in the measurement, the loss through one is half the S21
values. Still, most of the good match is due to losses. A 2:1 SWR is 10
dB return loss. Most of your earlier plots and SWR indicated at or less
than 1.5:1. This is certainly in line with the loss measurement. 1.5:1
SWR is return loss of 13.98.

Dave - W?LEV

Dave - W?LEV

On Tue, Mar 17, 2020 at 10:47 PM Kerr Smith <kerrsmithusa@...> wrote:

So, the match is good over HF. Thinking after I hit send: Why not
connect
the secondaries together as you did for the S11 measurement and do an S21
measurement to assess loss? That way, both ports are in a 50-ohm system.
I have just removed the 50 ohm resistor off the second transformer and
attached CH1 of the NanoVNA instead. The attached image is the S21 plot of
the sweep from 1 to 30MHz. At 7.15MHz the gain shows as -22dB.



--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
Re: Analysing Input Impedance Matching Circuit for the NE602

 

Here are some tests I did with 1 full turn on primary with 5 full turns on
secondary. Primary wire comes out one side and secondary out the other.
Ratio of 5 turns gives impedance transformation of 5 square = 25 so 50:1250

First graph is impedance with transformer terminated in 1200 ohms. Second is
VSWR with 1200 ohm termination. Tests were done on another type of analyzer.
Below are S11 plots of R + jX and |Z|, these look quite similar to yours I think - the Y-axis scales on mine are zoomed in a bit (I did try to set them from 75 to -75 on the Y-axis to match your scale but this caused NanoVNA Saver to crash).

Both these plots have CH1 of the NanoVNA attached to the second transformer's output (with a 50 ohm load the results are identical).

50 ohm transformer back to back S11 R_jX.png
50 ohm transformer back to back magnitude of Z.png

Re: Analysing Input Impedance Matching Circuit for the NE602

 

So, the match is good over HF. Thinking after I hit send: Why not connect
the secondaries together as you did for the S11 measurement and do an S21
measurement to assess loss? That way, both ports are in a 50-ohm system.
I have just removed the 50 ohm resistor off the second transformer and attached CH1 of the NanoVNA instead. The attached image is the S21 plot of the sweep from 1 to 30MHz. At 7.15MHz the gain shows as -22dB.

50 ohm transformer back to back S21.png

Re: Analysing Input Impedance Matching Circuit for the NE602

 

So, the match is good over HF. Thinking after I hit send: Why not connect
the secondaries together as you did for the S11 measurement and do an S21
measurement to assess loss? That way, both ports are in a 50-ohm system.

Dave - W?LEV

On Tue, Mar 17, 2020 at 8:22 PM David Eckhardt via Groups.Io <davearea51a=
[email protected]> wrote:

Looks pretty darn good to me. However, I must pose the question: how much
of that good-looking SWR and centered on the Smith Chart is due to loss?

Dave - W?LEV

On Tue, Mar 17, 2020 at 7:30 PM Kerr Smith <kerrsmithusa@...> wrote:

I have removed the two transformers from my test circuit and attached the
NanoVNA to the primary of the first one, the two transformers secondaries
(8 turns) are connected together and a 50 ohm resistor is attached to the
other end of the second transformer.

The results of this test are attached.



--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*



--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
Re: Analysing Input Impedance Matching Circuit for the NE602

 

Looks pretty darn good to me. However, I must pose the question: how much
of that good-looking SWR and centered on the Smith Chart is due to loss?

Dave - W?LEV

On Tue, Mar 17, 2020 at 7:30 PM Kerr Smith <kerrsmithusa@...> wrote:

I have removed the two transformers from my test circuit and attached the
NanoVNA to the primary of the first one, the two transformers secondaries
(8 turns) are connected together and a 50 ohm resistor is attached to the
other end of the second transformer.

The results of this test are attached.



--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
Re: Wich one the get ? nanoVNA F or H4

 

On Mon, Mar 16, 2020 at 02:51 PM, Lee wrote:

... but when I use polarized
sun glasses I can turn the nanoVNA 90 degrees from normal and get improved
contrast.
On a NanoVNA-H, a linear polarizer, like most polarized sunglasses, has relatively little affect on intensity, regardless of the orientation. But in conjunction with pair of "3D" glasses, crossed with the sunglasses, one can get complete extinction as the display is rotated, and increased transmittance relative to the sunglasses, with optimum orientation.

Awkward position for the polarizers, though, so leave it to a mechanical wizard to devise a contraption. Complete the fashion ensemble with an aluminum hat!

--
I_B_Nbridgema
Re: Analysing Input Impedance Matching Circuit for the NE602

 

Kerr,

Here are some tests I did with 1 full turn on primary with 5 full turns on secondary. Primary wire comes out one side and secondary out the other. Ratio of 5 turns gives impedance transformation of 5 square = 25 so 50:1250

First graph is impedance with transformer terminated in 1200 ohms. Second is VSWR with 1200 ohm termination. Tests were done on another type of analyzer.

Imp 1T to 5T transfomer 1200 ohm load.png
SWR 1T to 5T transfomer 1200 ohm lad.png

Re: Analysing Input Impedance Matching Circuit for the NE602

 

I have removed the two transformers from my test circuit and attached the NanoVNA to the primary of the first one, the two transformers secondaries (8 turns) are connected together and a 50 ohm resistor is attached to the other end of the second transformer.

The results of this test are attached.

50 ohm transformer back to back smith chart.png
50 ohm transformer back to back VSWR.png

Re: Analysing Input Impedance Matching Circuit for the NE602

 

Physically, yes. Circuit-wise and considering magnetics, its is a full
turn.

Dave - W?LEV

On Tue, Mar 17, 2020 at 6:16 PM Jim Allyn - N7JA <jim@...>
wrote:

The BN cores aren't actually toroids, they are "balun" cores or
"binocular" cores that have two holes through them. So, if you wind
through only one hole, you have a half turn.



--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
Re: Analysing Input Impedance Matching Circuit for the NE602

 

Try measuring VSWR and insertion loss by
making two transformers and connecting them back to back with a 50 ohm load
on the second core.
I will try this now and see what it looks like.
Re: Analysing Input Impedance Matching Circuit for the NE602

 

Hi Roger,

When I do one full turn on the primary (through the first hole and back down the second) I get the results as shown in the attached images.

This is why I removed part of a turn to see what would happen.

When I measure the inductance of one turn I get 7.38uH which is as close as I can get to my calculated value of 4.5uH (using 4 x 50 ohms for the impedance).

If I have a full turn I get about 12.5uH inductance which is about three times too large when compared to the calculated value.

1 turn VSWR.png
1 turn smith chart.png

Re: Analysing Input Impedance Matching Circuit for the NE602

 

Kerr,

Here is a link with actual tests of transformers made with 73-202 binocular cores. Make sure you use insulated wire because 73 Mix material has low resistivity compare to Mix 43.



Roger
Re: Analysing Input Impedance Matching Circuit for the NE602

 

Kerr,

Something is off with your results. I don't know how you are winding the binocular cores. You need full turns and one turn is a complete loop through one hole and back again. Try measuring VSWR and insertion loss by making two transformers and connecting them back to back with a 50 ohm load on the second core.

tr.png

Re: Analysing Input Impedance Matching Circuit for the NE602

 

Ok, understood, but a picture would help to clarify it.

El 17/03/2020 a las 19:16, Jim Allyn - N7JA escribi¨®:
The BN cores aren't actually toroids, they are "balun" cores or "binocular" cores that have two holes through them. So, if you wind through only one hole, you have a half turn.

--
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