[Elecraft] KPA temp drift and QSK clicks

[lhlousek]

I recently finished a KPA100, an excellent kit and very enjoyable to build.  I'm getting a nice, clean (assessed by
listening to the CW sig on another RX) 100+W on all bands and have had many nice QRO Qs with it already.

Before installing the KPA in my K2 I did the recommended spurious and harmonic mods (parts and instructions included
with the KPA kit), did the VCO voltage lowering mod to clean up keying on 40 meters, beat the 5th harmonic of the K2's 4
MHz osc with WWV at 20 MHz (a Ron AC7AC trick), ran Cal PLL, and redid the filters.  Frequency accuracy was very good
with the K2 reading 10 to 20 Hz high everywhere.  There was also very little frequency shift between filters.  I've
always noticed some frequency drift with temp and as the shack and the radio heated up the K2 read about 60 Hz high.
This has never been a problem and I find it perfectly acceptable.

However, running 100W, the rig can get pretty warm, particular during long CW rag chews, and it will drift as much as
280 Hz during the course of a QSO.  This is an unacceptable amount of drift.  Also, the filter-to-filter frequency shift
gets substantially worse.  I've always expected to put the KPA in an EC2 and this looks like another very good reason to
do so, perhaps along with a larger quieter fan.

One other thing:  I get clean,QSK at 10W but when the power is set to 11W (the KPA turns on) I hear clicking in the
headphones when sending.  This is true even in TEST mode where no RF is being generated.  Anybody else notice this or
have a fix for it?

Lou W7DZN