[Elecraft] K3 TX power foldback with SWR

[Jack Brindle]

Mike;

You should perform a calibration on your K3. The best way is to use the K3 Utility to step through the process. Otherwise the process is described in the K3 manual.
This should resolve most, of not all, of the problem. 

Let us know the outcome.

73,
Jack, W6FB


> On Mar 3, 2025, at 8:10 AM, Michael Carter via Elecraft <elecraft at mailman.qth.net> wrote:
> 
> For the first time that I can recall, I experienced my K3/100 reducing its TX output power abruptly (from 95 watts down to maybe 5 watts) on first transmission on a new frequency close to the one where the internal KAT3 ATU was tuned.  This occurred on multiple bands in this past weekend's ARRL DX SSB contest.  Since I rarely operate on SSB, and have never experienced this behavior on CW in years of contesting, I was perplexed.
> 
> This morning,  I explored the archive on both the original Elecraft reflector and the Elecraft-K3 at groups.io forum, and I found several mentions of the power foldback behavior.  VE3KI in one old post pointed out that the SWR change due to tuning away from the ATU tuning frequency may be modest, but the change in PA current or voltage may trigger the output power foldback.  I understand the basis for that protection.
> 
> My question:  how does one reset the TX power to full output after such a foldback event?  I tried an ATU retune on the same frequency on which the foldback had just occurred, but that didn't seem to restore full power.  I tried rotating the POWER control knob up and down around the desired output level, and that did seem to reset the TX output power to its original setpoint.  I was just tinkering during the contest and feeling like I didn't fully understand a methodical way to restore full power output.  Guidance from those who have dealt with this issue long ago is most welcome!
> 
> Thanks, and 73,
> Mike, K8CN
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