> I'm not talking about the difference in measurements in the chart
> vertically; I'm talking about the difference horzontally.
The measurement horizontally - at least min C/max L and max C/min L -
mean absolutely nothing because the tuner is not tuned properly.
What do you see with: 1) a 50 Ohm load connected to the antenna port
and the KAT3A bypassed, 2) a 50 Ohm load connected to the antenna
port and the KAT3A removed (KANT3 board installed), 3) a 50 Ohm
load connected to the antenna port and the KAT3A tuned for SWR =
1:1, 4) your "antenna" connected to the antenna port and the KAT3A
tuned for minimum SWR?
I do not have the tuner component values in front of me so I can't
calculate the impedance you are creating by min C/max L and max C/min L
but if the tuner has a 10:1 matching range you are running between
at least 5 and 50 Ohms or 50 and 500 Ohms depending on whether the
C is on the input output side of the inductor (basic L network).
The roughly 2:1 difference in current is believable for the 10:1
impedance mismatch - particularly if the controller is reducing
the drive (power output) as the mismatch exceeds 2:1 or 3:1.
73,
... Joe, W4TV
On 2020-05-12 3:08 PM, Nicklas Johnson wrote:
On Tue, 12 May 2020 at 11:51, Joe Subich, W4TV <[email protected]> wrote:
So I guess the question is this: is it expected to see such a large
variance in power consumption for the same output power based on the
values of C and L for the KAT3A?
Is the KAT3/KAT3A *tuned correctly*?
This came up because the rig is drawing a lot more current on 20m vs 40m,
when the KAT3A is tuned for the antenna (which is a better match on 20 than
on 40). For the dummy load, no, the KAT3A won't be tuned correctly when I
manually choose values for C and L; I just used it as a way to better
characterize the nature of the behavior that I was seeing and to reduce the
number of variables. However, as I mentioned, the behavior is similar when
running FT8 with the tuner correctly tuned for the antenna. If memory
serves, the difference in current draw was something like 6 amps between 40
and 20, though I can go measure that again if an exact value is useful.
You are comparing apples and oranges here. At 12W the 100 W amplifier
is bypassed. At 13W the 100W amplifier is engaged. The differene you
see is due to the 100W amplifier.
I'm not talking about the difference in measurements in the chart
vertically; I'm talking about the difference horzontally. I did the
measurements twice deliberately, specifically because PA is
bypassed/engaged, because I wanted to see if there was any relationship
there as well.
Nick
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