[Elecraft] KPA100 upgrade

[Don Wilhelm]

Stephen,

I am looking through the KPA100 upgrade documentation and am trying to 
understand what you have done.  I believe you are referring to the 
documentation for the KPA100MODKT when you state "installing the KPA100 
upgrade REV A. Oct 21, 2006"; and you are apparently referring to the 
KPA100 manual errata sheet when you state "changes listed in Rev E-2 Mar 
2007" - but I am not certain what you added - I need further clarification.

The manual errata sheets should *never* be used alone as any instruction 
- they should *only* be applied to those manual pages that they refer to.

So what did you *really* do?  Please clarify.  I can only guess, and 
that in itself can cause trouble.

If you applied the KPA100MODKT - and then subsequently changed C31, you 
should back off the change to C31.

Let me explain:

The C31 change only should be applied if the KPA100UPKT has been 
installed - the KPA100UPKT and the KPA100MODKT are two different 
animals.  Yes, that fact should be clarified on the Elecraft web pages 
because there is a lot of overlap between the two, but they *are* different.

If you have the blue toroids installed at RFC1 and L16, nothing at L16, 
and no RFC10 installed, then C31 should be the .22 uF 63 volt capacitor.

OTOH, if the cores for L5 and L16 are red, RFC10 and RFC1 are both 100uH 
chokes, then you need to have C31 as the .033 uF 200 volt capacitor.

As you can see from the voltage ratings, the C31 for the post-KPA100UPKT 
amplifiers will break down if used in an amplifier without the 
KPA100UPKT changes.

Again, please clarify in more detail exactly which changes you applied 
to your KPA100.

73,
Don W3FPR

himselff at nvtel.net wrote:
> I just finished installing the KPA100 upgrade REV A. Oct 21, 2006. I also did the changes listed in Rev. E-2 Mar 2007.  Now my K2/100 doesn't work correctly any more.  Any ideas from the masses.  I have spent the last three days trying to figure it out, but can't seem to do it by myself.
> 
> I started to go through the alignment process and couldn't get past the SWR calibration test.  
> 
> On 14 and 18MHZ it shows no SWR figures on the display panel and reads Hi current Intermittently.  I used to get 115 watts or so out on all bands.  Now the power output ranges from 10W to 90W maximum. Also in Tune position on any power setting, the power jumps back and forth about 10 watts or so on the bands that I get more than 10W output. 
> 
> The bands below are the worst
> 
> 21 MHZ = 10W
> 
> 14 MHZ = 10W
> 
> 18 MHZ = 10W
> 
> Anyone else have any problems after completing this upgrade that I just found out I didn't even need to do.
> 
> Stephen