Man, have I learned a lot about analyzers vs. vna's since yesterday.
All of you folks in this group who have responded have given me a wealth
of information.
Yes it seems few or none of the typical analyzers have the capability
to do the SOL compensation.
I see that the new(er) RigExpert Match for about $300 can do it
after purchasing a "license" for an additional $80.
There is also the FA-VA6 by Funk Amateur in Germany for a little less money.
Amazon lists a big pile of nano-vna's starting at about $80 and
up to around $700. I'm a little leary of them due to the made in
China factor, but could be convinced otherwise by someone who
has owned one for a while.
Anyway thanks a bunch to all who have weighed in on this.
Hopefully I am not the only one who received some benefit from
y'all.
Tom
K0SN
On Wed, Feb 11, 2026 at 2:57 PM Richard Karlquist <richard@karlquist.com>
wrote:
> What you are looking for is the "port extension" feature, which is "only
> software" but nevertheless is missing from many implementations. (Back
> in the stone age, port extension was a hardware feature implemented with
> a mechanical line stretcher, but now is pure mathematics). It's not as
> good as actually doing SOL at the end of the coax of coarse and depends
> on knowing the physical length of the coax and its velocity factor.
> Some implementations have a TDR function that allows you to determine
> these numbers for coax that is already up on the tower. Then you can
> enter them into the port extension feature.
>
> In a prior life I designed network analyzers for Agilent.
>
> ---
> Rick Karlquist
> N6RK
>
> On 2026-02-11 12:32, Jim Lux wrote:
>
> > Almost all of the current inexpensive VNAs can do this.
> > It's the de-embedding of the coax that might not be automated (unless
> > you cal at the end of the coax, which is inconvenient if the end of the
> > coax is at the top of the tower). Not all the VNAs have the ability to
> > "subtract out" the transmission line. Most of the programs that run on
> > a computer that talk to the NanoVNA and its ilk can do this.
> >
> > On Tue, 10 Feb 2026 11:40:20 -0800, Jim Brown
> > <jim@audiosystemsgroup.com> wrote:
> >
> > On 2/10/2026 11:03 AM, Jim Lux wrote:
> >
> >> This is where tools like the NanoVNA are really nice - you can
> >> calibrate at the end of the coax. Or, if you've measured the coax
> >> once, you can save it, and post process your data in one of the apps
> >> that takes VNA data (I use NanoVNA-Saver, but there's lots of others).
> >
> > A common use of analyzers is to simply use the SWR as a rough indicator
> > or resonance. The best can export a measurement as a data file (plain
> > text) that can be imported by freeware like SimSmith, which can then
> > "tune out" the coax by inserting a length of coax and varying its
> > length
> > until we see the normal Smith Chart view of resonance. I've used that
> > model to design switchable stub matching networks for my 80 and 40M
> > dipoles on the CW and SSB portions of the band. I've also used the
> > model
> > to optimally place along the line stubs to suppress power amp
> > harmonics,
> > and to eliminate interaction between harmonically related antennas in
> > close proximity. See k9yc.com/7QP.pdf for an example.
> >
> > For more than ten years, I've used the VNWA, built by hams in the UK
> > based on a design by German EE prof DG8SAQ, and using his control
> > software. That software can do that transformation and a lot of other
> > math, like transforming a measurement of an antenna fed by 75 ohm line
> > to show its true impedance.
> >
> > 73, Jim K9YC
> >
> > _______________________________________________
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
> > _______________________________________________
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|