[Elecraft] KPA100 Rev D

[Don Wilhelm]

Folks,

Before I get more questions indicating confusion, let me clarify in 
detail --

In my response below, I ignored the poster's reference to a "Rev D 
Upgrade kit".  There is no Rev D KPA100 - the closest I can imagine to 
Rev D is the manual revision, which is now Rev E.

The manual's rev letter is not linked to the board version (either 
populated or bare).
In this case, there have been only 2 versions of the raw KPA100 board - 
the Field Test level, and all others.  There have been 4 versions of the 
KPA100 - the Field Test version, then the first released version, and 
then the version which incorporated KPA100MODKT, and lastly, the version 
which incorporates KPA100UPKT.  This last mod kit has all the parts for 
upgrading any level KPA100 to the latest.  If your KPA100 has blue 
toroid cores at L16 and RFC1, you have the latest level.

The shield is a different matter.  There are 3 levels of the shield - 
the initial one with a wide notch at the SO-239 jack (about 1.4 inch 
wide), then one with a more narrow (about 1/8 inch (3mm)) notch at the 
jack, and lastly the addition of 2 solder lugs between the SO-239 jack 
and the outside surface of the shield - this last shield also added a 
shield for the speaker magnet since the magnet was sometimes responsible 
for interfering with the operation of relays K13, K14 and K15 on the RF 
board - some do it while others are just fine without the speaker shield.

73,
Don W3FPR

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Syd,

If your KPA100 has red toroid cores at L15 and L16, install KPA100UPKT. 
  That kit will upgrade any level KPA100 to the latest.  If you do not 
have a shield over the speaker magnet, add the KPA100SHLDKT as well to 
upgrade your shield.

Those mods will add significantly to the stability of the amplifier, and 
I highly recommend them.
Those mods were specifically created to address a tendency to oscillate 
a little above the 40 meter ham band under some conditions.  If you 
operate with an autotuner  that tendency to oscillate is quite high.

73,
Don W3FPR

On 3/31/2012 4:17 PM, Syd Smith wrote:
> I recently became aware of the Rev D upgrade kit for the KPA100 at
> Elecraft.  Where can I find a description of the changes and a
> recommendation of why I would want to install this kit in my Rev A
> amplifier which works FB.
>