[Elecraft] [K2] ALC and power control on 40m SSB in K2/100

[g0kla]

This is an old thread, but is something that I have struggled with on my own
K2.  I also had some RF feedback that was mixed with this, but I have cured
that.

So now I am left with the very similar symptoms where there are too many ALC
lights lit for 40m and it overdrives my KPA500.  I had to play with SSBA,
which I would set to 1 on 40m and 2 on 20m.  But even with SSBA set to 1 I
get much to much power on 40m for the amplifier.  I am using the MH2 mic.

I went through the checks.  I have the new PA.  There are only 1-2 ALC bars
lit on 20m and 15m.  There are typically 7 lit on 40m.

With SSBA set to 1 the voltage at KSB2 U1 pin 10 was not near zero.  It was
2.5V.  I checked the values and soldering of R14 and R15 and all looked ok. 
As were the other components listed.

Thinking that the incorrect voltage means that I should change the component
values I updated R9 to 15k and added a 1k between the base of Q1 and P1 pin
6.  The voltage is now near zero, but it has not improved things.

I still need to use SSBA 2 for 20m otherwise the drive is low.  But SSBA 1
on 40m has too much drive.  As soon as the KPA100 clicks in (as I turn from
10-11Watts) the amp is over driven.

Any suggestions?

73
Chris
ac2cz / g0kla





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