Scenario:
K3 + KAT-500 + KPA-500
All with latest firmware as of 1/1/2024
Prerequisites:
K3 ATU in Bypass.
Loop (wire) antenna tuned via KAT-500 "MAN" to 1.1 SWR.
Leave the KAT-500 in MAN not AUTO.
Goal:
To observe the KAT-500 and KPA-500 remain in a MAN (manual) tune configuration
without attempting to switch between BYPASS/MAN or BYPASS/AUTO as long as the
SWR Thresholds are satisfied.
Stimulus:
Operate the K3 in CW. As in a contest (CQ CALL or {EXCH} etc..)
Observations made:
Observed that the SWR on the KPA-500 is at the lowest value in the LED-file
(from left to right, left most LED is illuminated on the SWR meter)
Observed that the KAT-500 SWR LED meter only intermittently illuminates the
left-most (lowest) SWR indicator during CW transmission..
Expected Results:
The ATU-500 will not switch between bypass to memory based ATU settings.
Actual Results:
The ATU-500 clicks between Bypass and MAN (by "clicks", I mean only what I can
infer from the behavior -- it is as if the ATU-500 is either using the
memory-based ATU settings of the previously tuned settings and switching
between that and what seems like a Bypass mode) -- the clicking is rapid and
persistent at the onset of the CW message.
During CW transmission, at no time did the SWR in the KPA-500 SWR meter exceed
the left-most LED indicator and at no time did the KAT-500 SWR meter indicate
an SWR exceeding the left most (lowest) SWR indicator
Questions:
I am wondering -- is it a matter of difficult settings in the SWR Threshold?
I've perhaps chosen values that are causing this switch (clicking) to occur?
The impact is that when it is 'clicking' the power output to the amplifier
subsides for a fraction of a second -- and I can only guess that the actual
signal is effected while the KPA-500 and KAT-500 sort out what the tuner
settings ought to be -- in real-time.
What I'd like to know is -- if I manually tune the antenna with the KAT-500 and
leave it in "MAN" mode on the KAT-500 that the amplifier is NOT inhibited
unless the SWR exceeds a limit, but otherwise do not allow the KAT-500 to
signal the KPA to inhibit otherwise? Is that what is going on? The click into
Bypass and out of Bypass an edge case of the SWR Threshold handling ?
I've set the SWR Thresholds as follows:
Inhibit the KPA-500 if the SWR exceeds 1.6 SWR (act of paranoia to prevent the
KPA-500 to ever attempt to operate if the SWR is 1.6 or higher)
Force auto-tune if it exceeds 1.5 SWR
Bypass the KAT-500 if the SWR is below 1.1
By this setting, I am guessing that if the SWR during transmission (operation)
is above 1.1 and below 1.6 the KAT-500 will not a) Inhibit and b) not cause
Auto-Tune. And it also means to me that only if the SWR is below 1.1 (never
happens) that the KAT-500 will drop out of a MAN/AUTO mode and go into BYPASS
(I chose 1.1 specifically to prevent the drop into BYPASS -- an unattainable
SWR of 1.0)
Perhaps I'm doing it wrong. What kind of SWR Thresholds does Elecraft recommend
to literally prevent:
- The KAT-500 to drop into Bypass if the MAN setting is in force?
- Quell any attempt to do "Tune" while in MAN if the SWR is below X and above Y
SWR.
- Inhibit the KPA-500 if the SWR exceeds Z SWR.
For arbitrary X, Y and Z SWR levels.
Thanks. Ping directly if you need additional information.
HNY
---
73, Jeff W7BRS
https://blog.w7brs.com
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