KPA100 C83

[Brian Wruble]

Hi guys:  While assembling my KPA100, I unfortunately charged right by the
warning not to install C83 through the holes in the board.  I removed the
1000ufd cap and reinstalled it as recommended.  However, I am very curious
as to why it is specified to be mounted this way.  I have reviewed prior
postings here, and found this question, but never saw any answers.

Tnx de Brian W3BW


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[Don Wilhelm-3]

Brian,

I am not certain, but I will venture a guess that C83 will handle more
current when mounted with its leads bent over and soldered to the pads.  The
other thing I can think of is that the leads present a smaller inductance
when mounted that way.

73,
Don W3FPR

----- Original Message -----

> Hi guys:  While assembling my KPA100, I unfortunately charged right by the
> warning not to install C83 through the holes in the board.  I removed the
> 1000ufd cap and reinstalled it as recommended.  However, I am very curious
> as to why it is specified to be mounted this way.  I have reviewed prior
> postings here, and found this question, but never saw any answers.
>
>


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[John, KI6WX]

Brian;
When we built the original KPA100 prototypes, the optimum value of this
capacitor was not known.  If you make it larger, the amp draws more current
on 10 meters but is more stable.  With smaller values, you get better
efficiency on 10 meters but it is more prone to spurious oscillations.  It
is a lot easier to remove the capacitor when it is soldered directly to the
pads, so the instructions were changed to solder it to the pads.

The original prototypes and earlier production KPA100's used 1200pF.
Experiments showed that the value could be reduced without problems.  My
KPA100 has run for a long time with the value at 820pF.  It was eventually
decided that 1000pF was reasonable, so the production kits were changed to
this value and updates sent out to the earlier KPA100 builders.  Today, the
part could be mounted in the holes without any problems.
-John
 KI6WX

----- Original Message -----
From: "Brian Wruble" <[hidden email]>


> Hi guys:  While assembling my KPA100, I unfortunately charged right by the
> warning not to install C83 through the holes in the board.  I removed the
> 1000ufd cap and reinstalled it as recommended.  However, I am very curious
> as to why it is specified to be mounted this way.  I have reviewed prior
> postings here, and found this question, but never saw any answers.
>
> Tnx de Brian W3BW


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