Wayne gave us a way to read out what the ATU settings.
Does anyone have the formula or formulae for using "CT or CA and the L and C
values to determine the impedance presented to the ATU?
Thanks,
Ty, W1TF, K3 #696
--------------------------------------
Wayne wrote:
Most of the time you'll let the KAT3 automatic antenna tuner do its thing and
ignore it. It has a wide matching range and saves L-C information per-band and
per-antenna, so you'll rarely need to re-tune.
(We do plan to add multiple stored segments per band, too.)
If you're ever curious about the actual L and C values used in the matching
network, you can check them using a special setting of the KAT3 menu entry (in
the CONFIG menu). Just set KAT3 to LCSET, then exit the menu. Next, tap "ATU
TUNE". This will display the present L and C values.
For example, I just matched my K3 on a random wire antenna on 40 meters, went
into LCSET mode, and saw this when I tapped ATU TUNE:
CA 0.08 nF
L 0.25 uH
The "CA" means that the capacitance ended up on the antenna side of the
L-network. The other possibility is "CT", or capacitance on the transmitter
side. The capacitance is shown in nF (nanofarads) so it can fit into three
digits on the VFO A display even when the value is over 999 pF. The value
shown, 0.08 nF, could also be expressed as 80 pF.
Now, suppose you'd like to see what the effect of changing the L and C values
would be on the match. (Or you're troubleshooting the KAT3.) You can simply
rotate VFO A to change the C value, and rotate VFO B to change the L value.
Tapping "ANT" alternates between "CA" and "Ct". Having made a change, tap ATU
TUNE again to exit the L-C display. Then hold TUNE to go into transmit mode and
see the new SWR value.
Manual view/change of LC settings is certainly fun and educational. But it
could also be used to give me (your overworked firmware guy) feedback about a
difficult matching situation. I'm always open to fine-tuning the KAT3's
algorithm. So if you discover -- using LCSET -- that you're able to do better
than the KAT3 in auto-tune mode, just let me know.
73,
Wayne
N6KR
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