[Elecraft] K3 output power unstable

f5moo f5moo at cegetel.net
Mon Sep 22 10:11:15 EDT 2008


hello
the same probleme here K3 S/N 153
in ssb mode with the amplifier EMTRON DX2SP
the security overdrive

73 terry F5MOO



Kamal Sirageldin a écrit :
> Bjorn,
>
> I notice the same thing with my K3 S/N 775, V2.38.   For me, the problem
> appears to be in SSB mode, and not CW.  For example, if I adjust the power
> output of my K3 by a very small amount i.e. say from 50w to 52w output, it
> will initially transmit much more power than 52w  – driving my amplifier way
> past the limit for a second or two before settling back down.  It seems to
> me that it also does not necessary settle on the right power output.
>
> The problem also happens when you switch bands.  The transmitter power
> output will initially be very high (i.e. closer to 100W) and then appears to
> require some ‘settling’ time to go back to the power that it is actually set
> for when transmitting on SSB after a band change.  I do not have my K3 setup
> for a different  power output on each band.  But, I know my amp, and know
> the results of using other transceivers with it.  There is something
> definitely wrong with the (my) K3 power output management on SSB.   I do not
> use external ALC.  The amp is an Acom 2000A.  
>
> 73,
> Kam  N3KS
> Ksira at corpten.com
>
> 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)
>
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