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I am thinking to build discrete circuits for a specific non-resonant antenna to operate on HF bands without a remote tuner. I managed to snag one of the last MFJ-948F Versa Tuner II left in stock. (But, that's an indoor tuner. I want the tuning done at the base on a non-resonant antenna.) On a nice day thinking to bring the new tuner right to the base, tune it up for a few frequencies within each band. How could a NanoVNA gather values set on the tuner? Seems so possible to use a few parts and do this outdoor tuning in advance and for increased power. Smith charts are used for this matching. But, I don't know how to read discrete values from the Smith Chart on my NanoVNA. I suppose I could also open up the tuner, use meters for the measurement and build the same. Whatever, I am sure that my NanoVNA will confirm whether the tuning is correctly after an individual network is made. Please lead me down an easy path? Maybe I just need to buy a book and learn this?

Paul - KY4XJ

This is an interesting problem - I was doing the same, to characterize an LDG autotuner (what *are* the actual L and C steps).

There's two problems you've identified here:
The first is "what is the behavior of the tuner when it's set correctly" - A VNA will give you S parameters (you might have to make two sets of measurements, swapping the input and output).

From that, you can come up with a set of L and C (as wired in the tuner) in any of a variety of simulation programs, and adjust the values so that the simulated S parameters (or Y parameters or ABCD) match those you measured. The tricky thing is that there are parasitics on all the components, so even if the tuner is a CLC you might need to have some more R or L or C.

I highly recommend ELSIE from tonne software - the free edition works well, and it's got an easy interface. Windows only.


But if you want to do a multiband network, then you've got multiple sets of S parameters (one for each band or frequency) and then you want to "synthesize" a network that has that response.

This is a bit more complex. Typically, what you do is pick a topology, and iterate component values in an optimizer, where the thing to be optimized is the response at the frequencies. There are tools that do this (it's sort of like the optimizer in 4nec2) but I'm not familiar with any off the shelf tools (HFSS or ADS probably can do it).

I usually wind up writing some code in Python or Matlab.

This is an interesting problem - I was doing the same, to characterize an LDG autotuner (what *are* the actual L and C steps).

There's two problems you've identified here:
The first is "what is the behavior of the tuner when it's set correctly" - A VNA will give you S parameters (you might have to make two sets of measurements, swapping the input and output).

From that, you can come up with a set of L and C (as wired in the tuner) in any of a variety of simulation programs, and adjust the values so that the simulated S parameters (or Y parameters or ABCD) match those you measured. The tricky thing is that there are parasitics on all the components, so even if the tuner is a CLC you might need to have some more R or L or C.

I highly recommend ELSIE from tonne software - the free edition works well, and it's got an easy interface. Windows only.


But if you want to do a multiband network, then you've got multiple sets of S parameters (one for each band or frequency) and then you want to "synthesize" a network that has that response.

This is a bit more complex. Typically, what you do is pick a topology, and iterate component values in an optimizer, where the thing to be optimized is the response at the frequencies. There are tools that do this (it's sort of like the optimizer in 4nec2) but I'm not familiar with any off the shelf tools (HFSS or ADS probably can do it).

I usually wind up writing some code in Python or Matlab.

OK...Easy Path.

1) For one, the NANOVNA can not "read" tuner settings. You will have to
record those yourself.

2) The NANOVNA should be connected to the "rig" side of the tuner with a
SHORT piece of good 50-ohm coax (less than 2-feet long).

3) The antenna, itself, should be connected to the "antenna" side of the
tuner with a SHORT piece of good 50-ohm coax (less than 2-feet long).

NOTE: If you are interested only in 160 throughj 20 meters, the coax
lengths can be up to 3 or 4 feet long.

4) Diagramatic "tutorial" on the Smith Chart to determine resonance:

[image: image.png]
A) Anything above the "PURE RESISTIVE AXIS" is inductive and NOT RESONANT.

B) Anything below the "PURE RESISTIVE AXIS" is capacitive and NOT RESONANT.

C) Anything ON the "REAL RESISTIVE AXIS" is purely resistive and IS
RESONANT but may not be
at 50-ohms which you desire for a match to your 50-ohm coax.

D) ONLY THE CENTER marked in the center with the circle "50 ± j 0 OHMS" is
purely resistive and
50-ohms. This is where you need to adjust your tuner when connected
to your antenna
through the tuner to the NANOVNA. It will be a different setting of
the tuner and
NANOVNA for each frequency.

Let me know if this isn't clear enough. If you have questions, please
email.

Dave - W?LEV





On Tue, Jan 7, 2025 at 6:32?PM Paul Wolf KY4XJ via groups.io <xyroto=
[email protected]> wrote:

I am thinking to build discrete circuits for a specific non-resonant
antenna to operate on HF bands without a remote tuner. I managed to snag
one of the last MFJ-948F Versa Tuner II left in stock. (But, that's an
indoor tuner. I want the tuning done at the base on a non-resonant
antenna.) On a nice day thinking to bring the new tuner right to the
base, tune it up for a few frequencies within each band. How could a
NanoVNA gather values set on the tuner? Seems so possible to use a few
parts and do this outdoor tuning in advance and for increased power.
Smith charts are used for this matching. But, I don't know how to read
discrete values from the Smith Chart on my NanoVNA. I suppose I could also
open up the tuner, use meters for the measurement and build the same.
Whatever, I am sure that my NanoVNA will confirm whether the tuning is
correctly after an individual network is made. Please lead me down an easy
path? Maybe I just need to buy a book and learn this?

Paul - KY4XJ

--

*Dave - W?LEV*


--
Dave - W?LEV

OK...Easy Path.

1) For one, the NANOVNA can not "read" tuner settings. You will have to
record those yourself.

2) The NANOVNA should be connected to the "rig" side of the tuner with a
SHORT piece of good 50-ohm coax (less than 2-feet long).

3) The antenna, itself, should be connected to the "antenna" side of the
tuner with a SHORT piece of good 50-ohm coax (less than 2-feet long).

NOTE: If you are interested only in 160 throughj 20 meters, the coax
lengths can be up to 3 or 4 feet long.

4) Diagramatic "tutorial" on the Smith Chart to determine resonance:

SEE ATTACHMENT, PLEASE BEFORE PROCEEDING

A) Anything above the "PURE RESISTIVE AXIS" is inductive and NOT RESONANT.

B) Anything below the "PURE RESISTIVE AXIS" is capacitive and NOT RESONANT.

C) Anything ON the "REAL RESISTIVE AXIS" is purely resistive and IS
RESONANT but may not be
at 50-ohms which you desire for a match to your 50-ohm coax.

D) ONLY THE CENTER marked in the center with the circle "50 ± j 0 OHMS" is
purely resistive and
50-ohms. This is where you need to adjust your tuner when connected
to your antenna
through the tuner to the NANOVNA. It will be a different setting of
the tuner and
NANOVNA for each frequency.

Let me know if this isn't clear enough. If you have questions, please
email.

Dave - W?LEV

On Tue, Jan 7, 2025 at 6:32?PM Paul Wolf KY4XJ via groups.io <xyroto=
[email protected]> wrote:

I am thinking to build discrete circuits for a specific non-resonant
antenna to operate on HF bands without a remote tuner. I managed to snag
one of the last MFJ-948F Versa Tuner II left in stock. (But, that's an
indoor tuner. I want the tuning done at the base on a non-resonant
antenna.) On a nice day thinking to bring the new tuner right to the
base, tune it up for a few frequencies within each band. How could a
NanoVNA gather values set on the tuner? Seems so possible to use a few
parts and do this outdoor tuning in advance and for increased power.
Smith charts are used for this matching. But, I don't know how to read
discrete values from the Smith Chart on my NanoVNA. I suppose I could also
open up the tuner, use meters for the measurement and build the same.
Whatever, I am sure that my NanoVNA will confirm whether the tuning is
correctly after an individual network is made. Please lead me down an easy
path? Maybe I just need to buy a book and learn this?

Paul - KY4XJ

--

*Dave - W?LEV*


--
Dave - W?LEV

Since the OP wanted to make antenna matching circuits that are remotely switched, he should measure the antenna impedance at the desired frequencies with the nanovna then synthesize matching networks for those impedances to 50 Ohms. Seems the simpler path than measuring a tuner.
Gary
W9TD

Maybe I misinterpreted his intention. I thought he was going to mount the
(indoor tuner with protection) at the antenna base and manually adjust
recorded settings as he desired. Sorry about my misread. I made it more
complicated that it needs to be.

Dave - W?LEV

On Tue, Jan 7, 2025 at 8:30?PM Gary W9TD via groups.io <w9td=
[email protected]> wrote:

Since the OP wanted to make antenna matching circuits that are remotely
switched, he should measure the antenna impedance at the desired
frequencies with the nanovna then synthesize matching networks for those
impedances to 50 Ohms. Seems the simpler path than measuring a tuner.
Gary
W9TD

--

*Dave - W?LEV*


--
Dave - W?LEV

On Tue, Jan 7, 2025 at 12:29 PM, Gary W9TD wrote:

Since the OP wanted to make antenna matching circuits that are remotely
switched, he should measure the antenna impedance at the desired frequencies
with the nanovna then synthesize matching networks for those impedances to 50
Ohms. Seems the simpler path than measuring a tuner.

Great answer...

Roger

Many YouTube vids on the Smith Chart and tutorial PDFs are available also. Have a look. A few hours and you'll know how to use the chart...