Re: OT: Need Antenna Tuning Help

Posted by Ian Wilson on Mar 08, 2012; 7:15pm
URL: http://elecraft.85.s1.nabble.com/OT-Need-Antenna-Tuning-Help-tp7327188p7355992.html

The basic bridge in the MFJ - and lots of other impedance analyzers - is
insensitive to the sign of the reactive impedance. You can figure it out by
making a "small" change in frequency and seeing whether the reactance
increases or decreases. However, this takes additional software in the uP,
increases the measurement time, and guessing how large a small step
you can get away with is not trivial.

So I think that the original designer made a reasonable tradeoff. I wonder
who that was - the design was purchased by MFJ from Vectronics, I think).

73, ian K3IMW

On Thu, Mar 8, 2012 at 6:51 PM, Tony Estep <[hidden email]> wrote:

> On Thu, Mar 8, 2012 at 10:54 AM, WILLIS COOKE <[hidden email]> wrote:
> > I wouldn't have mentioned it Jim, except Tony's funny comment muddied
> the water...
> ===========
> Yeah, there's always some smart-aleck to confuse the issue. But
> seriously, I don't see why MFJ couldn't put a minus sign or something
> on the display. My cheapo Autek gadget (<$100 on ebay) tells you
> series and parallel reactance with sign, equivalent C, equivalent L,
> phase angle, and some other stuff as well as SWR. I'm not an
> MFJ-basher; I have been happy with all the MFJ stuff I have. But in
> this case IMHO they left out some worthwhile functionality.
>
> Tony KT0NY
>
>
> --
> http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352
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