I have found that power foldback for bad VSWR on SSB does not return to full
power after retuning the ATU. It takes a dot or two of CW to convince the radio
to return to full SSB power. (I have CW in SSB mode enabled, so it is not
difficult to do).
73 - Jim K8MR
On Thursday, March 6, 2025 at 10:18:04 AM EST, Dave New, N8SBE
<n8...@densbe.com> wrote:
Mike,
Maybe it was changing 'mode' or 'band' that did it?
On 2025-03-06 10:09, Dave New, N8SBE wrote:
> Mike,
>
> I've encountered this on my K3 and K3s in the past, and one thing is
> that the output power will recover after several seconds of
> transmission. I complained about this, and someone on the list pointed
> out that temporarily doing 'something' (sorry I don't remember what
> now, since I haven't touched my K3s since I upgraded to a K4D) would
> immediately clear the issue.
>
> Seems I remember that rebooting the K3 would do it, but that's a rather
> drastic measure to take in the middle of a contest, especially because
> some logging programs will complain quickly if the radio port is
> missing for even a couple of seconds.
>
> Not sure what search terms to use to find that conversation. Sorry I
> can't be more helpful. I feel your pain. I have archives of this
> maillist going back to 2009 on another computer, here. If I can
> remember, I'll see if I can find the conversation.
>
> 73,
>
> -- Dave, N8SBE, Hamshack Hotline 550-0971, HamsOverIP 101018,
> AmateurWire 1348
>
>
> On 2025-03-03 09:10, Michael Carter via Elecraft 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...@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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