[Elecraft] Barebone K2 Amplifier?

[Vic K2VCO]

Tom Althoff wrote:
> As hinted to in Don's comments there is another reason for going with the
> KPA-100.
> 
> I love the fact that the KPA-100 has an integrated solid state T/R switch so
> you can run full QSK.
> 
> Most of the imported amps are relay driven via the PTT line or RF sensing
> with a time delay and are not able to be keyed at normal keying speeds.

I might as well add my 2 cents.  Although I have a KPA100 I also have 
another amplifier which can be used with a barefoot K2.  It's a modified 
Henry Radio 100B, just a pair of 2SC2876's like the KPA100 uses.

I added a set of relay-switched lowpass filters from HFProjects 
<http://www.hfprojects.com/hfprojects/> and replaced the clunky t/r 
relay with a pair of Aromat (Matushtita) RSD12V reed relays.  These 
relays are almost totally silent and more than fast enough for full QSK 
at any paddle-sent speed.  The filter kit is complete, inexpensive and 
easy to put together.

Although you may not have an old 100B around, it would be easy to build 
a similar amplifier with CCI components 
<http://www.communication-concepts.com/hf_amplifiers.htm>.  They sell 
the boards, etc.

I use my amplifier with an Argonaut 515 that I've been playing with 
(yes, I still prefer my K2).  To use it with a K2, you would need to add 
an amplfier keying circuit such as that on the Elecraft website. 
Bandswitching can be with an external switch, or it can be automatic if 
you have a KRC2.

My amplifier easily produces 140w CW (100w recommended on SSB due to IM 
issues).  The main advantages of the KPA100 are that it can fit in the 
same box as the K2 and that it provides automatic bandswitching without 
a KRC2.
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco