Other questions was RE: [Elecraft] K2 Alignment and Test, Part III: High current

[Gil Stacy]

Kathy,

The K2 does not need the preamp on 40 meters.
Ron D'Eau Claire wrote ion the list in  Nov of 2004 how to determine when 
the preamp is used on the K2.  I quote from his post:

"The purpose of the preamp is to improve the noise figure on the
higher-frequency bands, not to make the receiver louder. It does that, of
course, but that's a secondary benefit. The issue is that the 'atmospheric'
or 'background' noise on the higher bands - usually above 15 MHz - can be so
low the internal noise in the K2 receiver could mask signals. The easiest
way to tell if that's true is to turn the preamp OFF, tune your K2 to an
empty frequency so all you hear is noise, set the IF filter for the
narrowest bandwidth you might use, and disconnect your antenna. If then
background noise level drops when you disconnect the antenna, you do *not*
need the preamp. The sensitivity of the K2 is entirely limited by the
background noise."

73, Gil NN4CW