K2/KPA100 Question

[Curt]

I built K2 s/n 06424 with KSB2 awhile ago, and am considering adding a
KPA100.  Wonder whether this will just foul up a good radio.  I recall
reading about oscillation and other problems with the 100W addition to the
K2.   Now, I am using a 30 year old radio for QRO SSB, but of course it
lacks WARC and takes up a lot of space I'd like to reclaim.

Appreciate knowing whether the issues have been ironed out and any advice
about making this change.  In particular, I have talked on air with a friend
who owns a K2/100 and his SSB signal on 40M is always weaker than any other
rig he uses.  Will the KSB2 need to be reconfigured after adding a KPA100?
I'm mostly a CW op, but like to work phone sometimes also.

Also, what else would I need to add to facilitate computer control and
PSK31(which I only use rarely) using the K2/LPA100.   My ultimate goal is a
single small size rig and laptop on the desk, with everything else clear.

Bottom line, is adding a 100W amp to what was originally a great QRP rig
just asking for trouble?

72/73 Curt KB5JO

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[Don Wilhelm-4]

Curt,

Those reports of oscillation in the archives are only a few scattered
reports and can usually be attributed to build errors or early problems
that have now been corrected.   The KPA100 design was changed (in 2008
IIRC) to cure those oscillations.

Your friend whose 40 meter SSB is weaker than his other radios could be
due to either the audio drive and compression he is using, or could be
due to the calibration of his KPA100 wattmeter.  It is difficult to
answer that concern unless I have the specific K2/100 on my workbench.

The KSB2 does not need to be re-configured when adding the KPA100. Just
follow the instructions for the KPA100 installation (be aware of the
Serial number for your base K2 and follow the appropriate set of
instructions).

73,
Don W3FPR

On 9/10/2012 12:42 PM, Curt wrote:

> I built K2 s/n 06424 with KSB2 awhile ago, and am considering adding a
> KPA100.  Wonder whether this will just foul up a good radio.  I recall
> reading about oscillation and other problems with the 100W addition to the
> K2.   Now, I am using a 30 year old radio for QRO SSB, but of course it
> lacks WARC and takes up a lot of space I'd like to reclaim.
>
> Appreciate knowing whether the issues have been ironed out and any advice
> about making this change.  In particular, I have talked on air with a friend
> who owns a K2/100 and his SSB signal on 40M is always weaker than any other
> rig he uses.  Will the KSB2 need to be reconfigured after adding a KPA100?
> I'm mostly a CW op, but like to work phone sometimes also.
>
> Also, what else would I need to add to facilitate computer control and
> PSK31(which I only use rarely) using the K2/LPA100.   My ultimate goal is a
> single small size rig and laptop on the desk, with everything else clear.
>
> Bottom line, is adding a 100W amp to what was originally a great QRP rig
> just asking for trouble?
>
> 72/73 Curt KB5JO
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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[George Winship, NC5G]

On Monday, September 10, 2012, Curt KB5JO wrote:

<I built K2 s/n 06424 with KSB2 awhile ago, and am considering adding a
<KPA100.  Wonder whether this will just foul up a good radio.  I recall
<reading about oscillation and other problems with the 100W addition to the
<K2.  

The early KPA100 did have this problem, but it was ironed out years ago. An upgrade kit was/is offered for those early KPA100's and the design changes were incorporated in the rest of them.  

<Appreciate knowing whether the issues have been ironed out and any advice
<about making this change.  In particular, I have talked on air with a friend
<who owns a K2/100 and his SSB signal on 40M is always weaker than any other
<rig he uses.  

I have one of the early KPA100's, did the upgrade and have never had any issues with it since. No problems with output on any band phone or cw.


<Bottom line, is adding a 100W amp to what was originally a great QRP rig
<just asking for trouble?

Absolutely not. Been a happy K2/100 owner for 11 years.

73,
George, NC5G