K3 output power unstable

[Bjorn]

I am right now in the middle of the SAC contest when I notice that the K3
has a problems keeping output power stable. I noticed some excessive high
output from the amp when investigating I found that my K3 set to drive the
amp with between 20-30 watt output depending on band, delivers substancially
more. Ouptut power pulsate between nothing and full power, delivering more
than 100 watts in bursts into the amp (designed for 30W input).

The problem is easiest to reproduce on 80 meters, but I am sure I saw the
power wobble a few seconds b4 stabilizing on higher bands to. Even when the
radio has cooled down to a PA temp of 34C the problem is there.

I think I read somthing about a similar prioblem somewhere, would apreciate
any leads that I might help to narrow down and eliminate the problem.

73 de Björn /SM0MDG (SE0X in SAC)
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[GW0ETF]

Bjorn wrote

I am right now in the middle of the SAC contest when I notice that the K3
has a problems keeping output power stable. I noticed some excessive high
output from the amp when investigating I found that my K3 set to drive the
amp with between 20-30 watt output depending on band, delivers substancially
more. Ouptut power pulsate between nothing and full power, delivering more
than 100 watts in bursts into the amp (designed for 30W input).

The problem is easiest to reproduce on 80 meters, but I am sure I saw the
power wobble a few seconds b4 stabilizing on higher bands to. Even when the
radio has cooled down to a PA temp of 34C the problem is there.

I think I read somthing about a similar prioblem somewhere, would apreciate
any leads that I might help to narrow down and eliminate the problem.

73 de Björn /SM0MDG (SE0X in SAC)
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Bjorn,

I posted about this very problem a couple of months ago but had virtually no feedback so it's interesting to hear of someone else being affected. As you say the power would drop quite suddenly then come back up; when running an amp it once went right up to ~100w even though set for about 35w - it tripped the amp....

Seems to do this on phone too but cw is easiest to see when it's happening. To be honest it has hardly happened to me at all recently and I wonder if you have the latest firmware installed. I did contact Elecraft support and I seem to remember they said it was an AlC control software problem and to keep downloading the latest firmware which would eventually sort it, and as I say it seems much better now here. However the other day I was on phone and the power was all over the place; it then started giving me TXG Error messages and I had to do the 5 and 50 watt power output config from start to finish which seemed to fix it.

Good luck in the contest - family duties here else I would be giving away some points for you....

73,

Stewart Rolfe, GW0ETF (K3 145)

[Bjorn]

Stewart,

Thanks for your responce to my question. The problem is on 80 meters,
other bands seems fine. When letting my K3 cool over dinner to about
30C output it became stable again. Working the temp up a few degrees
is enough to make it go wild again. Giving the box a gentle knock on
the cabinet seems to make a difference.

Haven't had any problems like this b4, but this is the first time I
use 80 since I mounted the sub rx. Maybe there is a mechanical issue
as a result of this...

73 de Björn /SM0MDG
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