KLPA3A power transistor thermal stress concerns

I agree and I have previously mentioned this on the Elecraft list. it
would be nice if you could control when the 100W PA engages. I would
prefer 10 watts.

John KK9A



KD8RQE wrote:

The K3/100 switches to the KPA3A at 12 watts.  So is there a 2w range
(10-12w) where the KLPA3A is putting out unacceptable IMD?  Is there a way
 to
make the switch at 10w, or should we just avoid that 2w "danger zone"?

73

Mike KD8RQE


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[Ignacy]

Seems a bit artificial problem, unless someone is driving an amp that
requires 12 W. My modified Expert 1.3k-fa requires about 6W to 8 W for 1 KW
output.
 
If a serious concern, increase voltage to 15V. The Yahoo KX3 group has
graphs of IMD3 as a function of power and voltage. Increasing voltage at 12
W by 1 V decreased IMD3 by about 10 db. I assume that the LPA in K3 is
similar to the amp in KX3.  

Ignacy, NO9E



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[Wes Stewart-2]

Did they do IMD as a function of frequency?



On 10/25/2017 8:48 AM, Ignacy wrote:

> Seems a bit artificial problem, unless someone is driving an amp that
> requires 12 W. My modified Expert 1.3k-fa requires about 6W to 8 W for 1 KW
> output.
>  
> If a serious concern, increase voltage to 15V. The Yahoo KX3 group has
> graphs of IMD3 as a function of power and voltage. Increasing voltage at 12
> W by 1 V decreased IMD3 by about 10 db. I assume that the LPA in K3 is
> similar to the amp in KX3.
>
> Ignacy, NO9E
>
>

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[Wes Stewart-2]

Don't think so from the description Wayne gave on the KX3 Yahoo group.

Wes N7WS

On 10/25/2017 8:48 AM, Ignacy wrote:
> I assume that the LPA in K3 is
> similar to the amp in KX3.
>
> Ignacy, NO9E

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