AD6XY wrote:
>
>
>
> Joe Subich, W4TV-4 wrote:
>>
>>
>> Since the K3 power control is based on average power and not
>> instantaneous (absolute) peak power, the power level (both
>> requested and reported) can not be relied on as a gauge of
>> proper operation unless the user knows with certainty how much
>> headroom is required to handle the peak power without compression
>> or clipping.
>>
>>
>
> Unfortunately, the life of amplifier power transistors and to a lesser
> extent valves is based on the peak power. Most license conditions are also
> based on peak power.
>
> A power control based on average power is therefore, irrespective of any
> technical merit, inappropriate. It is theoretically illegal in many
> countries to use with a following amplifier as well as being likely to
> result in damage to that PA.
>
> This is why it is such a serious issue and why we keep banging on about
> it.
>
> Mike
>
>
If what Joe claims is true then this is a more serious issue than even I
imagined, since it affects SSB operation as well as data modes. It would be
so serious that I suspect he is wrong about it.
If I dial up 100W in SSB or data I expect the power to be limited to 100W
PEP, not 100W average power.
One reason I suspect he is wrong is that the observation of getting around
twice the requested power applies to any data mode, not just PSK31. I can
feed a pure sine wave in, request a power of 5W, and get 10W out. If the K3
power meter was indeed average level then it should still limit the power to
5W as it does in SSB.
The issue here is not how the K3 power control works. It is that it is not
working in DATA A as it does in SSB. DATA A ought simply to be treated as
another SSB mode that just allows a different choice of audio input and
filter settings. I believe that it did originally work like that in early
versions of the firmware.
Sorry to continue the topic after Wayne requested we call a halt on it, but
the assertion made by Joe opens up a whole new can of worms if he is indeed
correct about it.
-----
Julian, G4ILO. K2 #392 K3 #222.
http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham
Directory http://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3
--
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