[Elecraft] Re: Changes from 1000 watts to 10 watts

[lhlousek]

<This is a critique of the Elecraft K2/100.>

I agree.  On CW, there isn't  huge benefit to running 100W over 10W.  That's why I've been running at least 1KW.  BTW,
if you're proud of your ability to copy weak sigs, you might try running the legal limit.  It's amazing how many you'll
hear calling you.  It seems to me that copying-wise, running QRP is easier because often the STNs you QSO are louder
than you.

IMO, the K2/100 has a number of shortcomings as an exciter. The QSK is rather slow.  It has no ALC input and no TX
inhibit, both being very useful in protecting the amp and the PIN diode QSK switch in my amp.  Perhaps the biggest
problem is that the output power fluctuates making tuning an amp problematic.  The fluctuation is caused by the
algorithm used by the K2's internal ALC and the low resolution of the power setting DAC (U8 on the control board).  In
my K2, each DAC step corresponded to a power change of ~1W, depending on band.  When I adjusted the power control, I
might get 4.5 W or 5.5 W but couldn't get anything in between.  With the KPA the minimum step size was >12W on some
bands!  There is an application note on the Elecraft website addressing this (increase the value of R98 on the RF board)
and in my case the best I could do was to reduce the steps to around 1/3W and 3W respectively.  Three watts may not seem
like much but when an amp requires only 50W of drive, random 3W fluctuations in power make it very difficult to tune the
amp.

Because of these issues, I don't regularly use the K2/100 with my amp.

Lou W7DZN