K3 SSB Power Reduction

[N0QO]

Hello, This is my first post to this group.

Has any other K3 owners experienced the something similar to what I will attempt to describe below?

At times I am noticing a reduction in peak talk power by as much as 50% below what would be expected at any given power setting.  I am measuring this in an LP100A and it is also noticeable on the internal K3 meter. I have noticed this with both the low power and high power amps.

This does not occur key down!  Although key down via the tune button does seem to temporarily resolve it.  I am able to replicate it easily on 10M.  If I switch to that band and I am not getting the expected peak power I can then hold the tune button and after tapping the tune button to get out of the TX cw mode I have the talk power I expect.  If I change bands say to 12M and come back to 10m the power is again below what it should be and I repeat the process above and all is well.  I have seen this on all the bands I operate which are 80-6m.  .

I have gone through the power calibration process several times and it does seem to give some temporary relief but it always comes back.  I also noticed another post that may be related where someone suggested that the LPA board may need to be reseated so I tried that with no change in results

I have a K3 ser. number 1047, 100W, no ATU, no external audio processing and am currently running the 2.02 firmware and associated DSP.  I have also tried all of the Beta release with no noticeable difference.

73, Ken N0QO

[Julian, G4ILO]

N0QO wrote

Hello, This is my first post to this group.

Has any other K3 owners experienced the something similar to what I will attempt to describe below?

At times I am noticing a reduction in peak talk power by as much as 50% below what would be expected at any given power setting.  I am measuring this in an LP100A and it is also noticeable on the internal K3 meter. I have noticed this with both the low power and high power amps.

This does not occur key down!  Although key down via the tune button does seem to temporarily resolve it.  I am able to replicate it easily on 10M.  If I switch to that band and I am not getting the expected peak power I can then hold the tune button and after tapping the tune button to get out of the TX cw mode I have the talk power I expect.  If I change bands say to 12M and come back to 10m the power is again below what it should be and I repeat the process above and all is well.  I have seen this on all the bands I operate which are 80-6m.  .

I have gone through the power calibration process several times and it does seem to give some temporary relief but it always comes back.  I also noticed another post that may be related where someone suggested that the LPA board may need to be reseated so I tried that with no change in results

I have a K3 ser. number 1047, 100W, no ATU, no external audio processing and am currently running the 2.02 firmware and associated DSP.  I have also tried all of the Beta release with no noticeable difference.

73, Ken N0QO

I noticed this when I first got my K3 way back in January when I was trying to set up gain levels etc. If you look back then there have been a few posts suggesting others have noticed the same thing. There have been many firmware updates since then and I don't use SSB that much, so I haven't really noticed it, but I don't have the benefit of a good inline power meter like you and it probably would not be very noticeable on the K3 meter especially as it is not a constant occurrence.  I used to experience lower than expected power on data modes as well.

I may be spouting nonsense here, but I think the K3 - like the K2 - has a firmware based ALC that adjusts the overall gain to give the desired output level. It adjusts the level and then remembers it for subsequent transmissions.

With the K2, I got used to the fact that the first data mode transmission of the day would start off at about 2W and then increase over a few seconds to the requested 5W. Subsequent transmissions would always give the requested power right from the start.

I'm wondering if the K3 uses a similar algorithm, and that it is somehow remembering an incorrect gain setting instead of recalibrating the gain for that band, so that you have to force it to do so by engaging Tune mode or changing to another band.