The ATU uses 10 kHz segments below 3 MHz. And then 20 kHz segments 3
MHz through 26 MHz. And 100 kHz segments from 38 MHz through 30 MHz.
And 200 kHz segments 38 MHz through 60 MHz.
The understanding regarding 80M would then be the segments are 20 kHz
wide and not 10 kHz wide.
73
Bob, K4TAX
On 12/10/2019 5:56 PM, K9MA wrote:
I understand that the ATU uses 10 kHz segments on 80, which was at
some point changed from 20 kHz. That means the center points are 3505,
3515, etc. There is some hysteresis when tuning, but I'm not sure that
consistently explains where it switches. It also won't switch until
you stop tuning for 1/2 second, or so.
Another factor is that the ATU only measure frequency to, I think, 8
kHz. The net result may be that sometimes it's not in the frequency
segment you think it should be in. Unless you have a very narrow band
antenna, it shouldn't make much difference.
73,
Scott K9MA
On 12/10/2019 17:03, [email protected] wrote:
After saving my KPA-1500 ATU impedance matching parameters on 80M at
20 Kc intervals (3.510, 3.530, 3.550, 3.570, etc, etc), I expected
that the KPA-1500 ATU would automatically switch to the next set of
L/C values at the midpoint of the 20 Kc segments (like 3.520, 3.540,
3.560, etc, etc), but I find that it switches randomly, sometimes
just 2 Kc away from the main tuning frequencies. Does anyone have
information on how the ATU is supposed to work when it is polling the
xcvr for frequency?
Thanks, K5UA
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