[TowerTalk] MFJ226 / SARK110

[Jim Brown]

On Wed,7/8/2015 7:30 PM, Richard (Rick) Karlquist wrote:
> I am not sure what Jim means by a "full" VNA.  There are a growing
> number of low cost analyzers that have the same architecture as
> this one, which combines a 1 port network analyzer with a 2nd receiver
> port.  These devices can sort of measure S11 and S21, but do not
> offer full two port calibration with 12 term error correction like
> "real" network analyzers do.  Depending on what you are doing, these
> limited analyzers might make acceptable measurements.  Or they may
> have unexplained response ripples.

It's  not a $50K Agilent (or whatever they're called this week). But 
it's good enough that N0AX was going to give it a glowing review in QST 
(and buy one for himself) until WX0B yelled about patent rights. And 
it's good enough that when AC6P, a prof at UCSC, did a repair on mine by 
replacing some SMT parts, he liked it enough that he bought one for 
himself.

And -- the calibration routines seem to be well thought out. Take a look 
at the manual, which is online.

>
> Specific to VNWA3, the output level is only -17 dBm.  This weak drive
> level is unlikely to do well when measuring 160 meter antennas in
> the presence of BCB QRM.  Again, this may or may not be an issue
> depending on your circumstances.

Agreed.

>
> It goes to 1.3 GHz, but with reduced accuracy at high frequencies.

As I read it, it's reduced dynamic range.

> I don't like the axis scaling and labeling in the GUI.

Yes, it's typically German. I had similar issues with acoustic modeling 
and measurement software for which I was a beta tester. But the 
developers, who had become personal friends, implemented my suggestions 
for improvements.

> The competition in this space seems weak compared to this model,
> so it may be best in class, but realize its limitations. 

So far, the only limitation I've run into is that the I/O can't handle 
much RF. :)

73, Jim K9YC