[Elecraft] K2 / KPA ALC problem.

[Don Wilhelm]

Chris,

Is there any chance you have T4 wound for the "better efficiency at 5 
watts" ratio of 2:2:1:1 turns?
If so, be aware that this winding ratio is *only* for a QRP CW only K2.  
If the KSB2 is added, it must be changed to the standard 2:3:1:1 ratio.
With the 'better efficiency at 5 watts" mod applied, the efficiency 
above the 5 watt level becomes very poor, and may generate HiCur 
messages.  It should never be used if the KPA100 is added.

73,
Don W3FPR

On 12/3/2013 12:14 PM, Chris Kimball wrote:
>
> Don,
>
> My KSB2 is revision E, July 20, 2004, with the "PSK31 ALC time constant
> change" of KI6WX built-in.  It doesn't have the increased RF gain mod.  Is
> there a reference to the mod that you suggest with the R9 -> 15K and a new
> 1K  in the Q1 base?
>
> I was amazed at the instability at the 5W level under tuning to a dummy
> load.  The measured power levels alternate between 4.3 and 6.4 W with no
> points in between.  Seems like too much. Since I don't have a pot in this
> range, I'm tempted to double R98 and see what happens. (I currently get 6.8
> W on 10 meters for a 10 W setting and it doesn't bother me.)
>
> Please let me know about the "1K in Q1 base" mod.
>
> Thanks,
>
> Chris
> NQ8X
>
>
>
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