[Elecraft] K2 ALC problem

[David Woolley (E.L)]

Gary D Krause wrote:
> 
> I've noticed that my power output on 40 meters LSB is a lot higher than 
> expected.  I get four to five bars or more on the peaks in the ALC 
> mode.  I even got a high current reading last night and I then turned 

The number of bars in ALC display mode does not indicate the output 
power; it indicates the transmit chain gain (more accurately the excess 
gain over that needed to achieve the demanded power).

The K2 does have more or less maximum gain on 40m.  I suspect that the 
gain drops with increasing frequency because the transistors' gain 
reduces with frequency, and it drops with decreasing frequency because 
the coupling transformers are less effective.

The ALC is greatest on 40m to stop the output power being greater.

> the power back from 12 watts to 10.  I get 4 to five bars even at five 
> watts.  It didn't make much difference and I've found that I need to 
> hold the mic further away. I switched to USB on 40 meters and it looks 
> fine.  It looks good on the higher USB frequencies also.  I've noticed 

That's weird.  Any difference between USB and LSB should switch between 
USB and LSB on the higher frequency bands.

> that it is around 2 to three bars on 80 meters LSB which is normal 
> according to the manual.
> 
> I'm wondering if it could be a carrier balance adjustment?  Any ideas 

A severe carrier balance problem would result in their being ALC bars 
lit when there was no audio.  As the carrier is also suppressed by the 
filter, I'm not sure that you would get enough leakage to trigger this, 
though.

If the sideband switched at higher frequencies, I would suggest the 
problem was that your filter 1 wasn't correctly aligned for one of the 
sidebands, but if it is always the one sideband that needs more ALC, I 
have difficulty in imagining a mechanism that would cause that.

> would be greatly appreciated.  Everything else appears normal.  I've 
> checked all solder connections on the SSB board several times and 
> re-flowed the connections I considered suspect.


-- 
David Woolley
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