[Elecraft] RE :KPA100 upgrade and KAT100 problem

[Don Wilhelm]

John,

I had forgotten about C80 and C81 - yes change them to .0047 uF (472) - and
change R19 and R20 to the new non-inductive resistors.

I believe Ron made a mistake in his email - C58 and C59 which are nearby are
the 0.1 uF (104).

Here is what happened on C80 and C81 - for a short time after the 20 and 17
meter low power output problem, it was thought that the C80 and C81
capacitors had to be a higher value.  Well as things turned out the problem
was really that the resistor manufacturer had changed R19 and R20 (1.6 ohms)
to an inductive design without notifying Elecraft.  So a few (but very few)
KPA100 kits went out with the 5600 pf capacitors.  You should replace R19
and R20 at the same time just to be certain you have the non-inductive
resistors.  A note to Elecraft (mailto:parts at elecraft.com) asking for 2
E530102 4700 pF capacitors and 2 E500130 1.6 ohm 2 watt resistors should
have the required parts to you in short order.  While you are at it, get 2
1N5711 diodes PN E560004 just in case the high power oscillation zapped your
KAT100 wattmeter diodes again.

73,
Don W3FPR

> -----Original Message-----
>
> Ron -
>
> I suspect the same has happened to the KAT100.  I did replace the diodes
> and it worked for a bit, but the problems quickly returned.  Probably
> blew up the second set of diodes.  Setting the KAT100 aside until the
> KPA100 behaves.
>
> In C80 and C81 I have caps marked "562".  The revision D manual says
> these should be 472's, as do prior manuals.
>
> I then found the "KPA100 Cap Kit Upgrade"  which replaced C80 and C81
> with 562's (5,600 pF).
>
> Should I go back to 472's?
>
> You use .01 uF.  Would that be better?  How did you arrive at .01 uF for
> C80 and C81?
>
> All help greatly appreciated.
>
> 73 de K1ESE
> John
>
>