[Elecraft] K60XV ALC

[Mike Harris]

G'day,

Just completed a K60XV, also changed R6 in the KAT2 to 470 ohms.  All is 
working well apart from the old ALC problem first reported in April this 
year.

My setup is K2 with the QRP top which includes the KAT2 and KIO2, followed 
by an outboard KPA100/KAT100 in an EC2.

With the external combo disconnected from the K2 and the KAT2 in CALp or 
CALs the low level output from the K60XV behaves as it should.  With the 
KAT2 in AUTO I can only get an indicated output of 0.21mW.  Nothing new 
there, similar symptoms to those previously reported.

However, something which was never confirmed or otherwise in previous 
posts, to my knowledge, is that with the KAT2 in CALp the KAT100 has 
exactly the same effect, it scuppers the K60XV low level output.  Change 
the KAT100 to CAL and all is normal.  Just to be sure, I disconnected the 
KAT2 RF and auxbus cables and fed the outboard units from the base K2 rf 
port.  With the internal auxbus link from the KPA100 disconnected from the 
KAT100 the KAT100 is dead and all is OK.  When the external auxbus cable 
from the KIO2 is transferred to the KAT100 the KPA100 is dead and the 
KAT100 functioning the problem returns but is resolved by putting the 
KAT100 in CAL mode.

Now, given that the SWR bridge circuitry is exactly the same in the KPA100 
and KAT100 it can't be that which is causing the problem and raises doubts 
about the KAT2 R6 mod to 470 ohms being the whole answer to the initial 
problem.

It was also noticed that there was a small change in RF level if the KAT2 
mode was toggled between CALp and CALs.

So unless I have another previously unnoticed problem of some sort causing 
my symptoms I believe there is something else in play here other than R6.

Regarding the K60XV installation, my firmware seemed to have defaulted the 
D19 parameter to PA60=80 instead of PA60=40 as stated in the manual. 
Noticed when verifying proper output from the KPA100 on 60 metres, 50W 
selected, about 5W out until PA60=40 was selected thereafter 50w selected, 
50w output.

Regards,

Mike VP8NO