[Elecraft] K2 and the KPA100 Power Fluxuates?

[Harry Yingst]

Thank you

--- Ron D'Eau Claire <rondec@easystreet.com> wrote:
> I've experienced that too, but I've been swamped and haven't had time
> to
> pursue it. A buddy and fellow Elecraft owner, Lou, W7HV, sent me this
> info
> about the problem:
> --------------
> If you haven't done this already, it's easy to check to see if the
> ALC is
> causing the steps.  Pin 2 of U8 on the control board is the ALC
> control.
> It's 8 bits out of 5V so an LSB is .02 volts.  If you see .02V
> changes
> correlating with your power jumps, then that's it.  
>  
> Increasing R98 on the RF board reduced ALC gain so the effective
> resolution
> of the DAC goes up.  Just make sure that the ALC output isn't
> saturated at
> full power  on 10m (without the KPA installed).  I increased R98 to
> 1.33K
> and got 4V out of the DAC at 10W on 10m.  Valc (output of Q8 on the
> control
> board) was 6.3V.  Valc maxes out at 7.5V so I had about 1.2V of head
> room.
>  
> I believe there is a tech note about this on the Elecraft website
> somewhere.
> -------------
> 
> Ron AC7AC
> K2 # 1289
> 
> -----Original Message-----
> I raised this question when I first built my KPA100.  On my unit at a
> set
> 20W output the power fluctuates between 17 - 22W.  This makes it very
> difficult to set the SWR bridge pots for example in the KAT100....
> 
> Mike VP8NO (IOTA SA-002)
> GQRP 10148
> QRP-Canada #57
> K2/100 #1400
> 


=====
Harry - AB2PN

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