[Elecraft] K2 #2740 Up And Going!

[k6se@juno.com]

Jim, W7RY wrote:

"Is there an alignment for R-60 ?  It is set at max counter clockwise
position. (That is where the instructions tell you to set it when it's
installed)."
==========
The last sentence on page 107 of the K2 manual says, "R60 is adjusted for
the desired clas AB standing current using voltage/current monitor mode
on the LCD."

On sheet 4 of the schematic, R60 is labelled as "PA Bias Set - CCW=Min
Bias".  The voltage chart says the top of the pot (Q13 emitter) is 0.6
volts in transmit mode (but doesn't say whether this is in the CW or SSB
transmit mode).

Also on page 107, it says that the PA operates in ~ class B on CW and
class AB on SSB, apparently controlled by the "/CLASS AB" signal from pin
6 of U1 which goes low in the SSB mode, putting the bottom of R60 closer
to ground ptoential and causing Q13 to conduct harder than when on CW.

But it doesn't say anything else in the manual exactly how to adjust R60.
 I'd like to know myself.  All K2's have R60 fully CCW, so maybe the
engineers decided that was the correct setting and why they did not
include an adjustment procedure.

Eric, Wayne, or Gary:  How about it?

73. de Earl, K6SE