[Elecraft] K2 SSB Power Overshoot on First Syllable

[David Woolley]

This is all, unfortunately, in the proprietary part of the K2, the 
firmware. The K2 doesn't have a gain calibration tables, and I'm not 
sure if it even saves gain settings between transmissions.

With CW it will know that the first transmit level it sees is full 
power, so my guess is that it starts low and builds up to that, but for 
SSB, it won't know when the peak has been reached, so it is going to set 
the transmit gain before it reaches peak and then back it off, but there 
will be a delay in backing it off.  Remember it is primarily a CW 
transmitter.

I would guess, to minimise this, you should set your audio drive levels 
low enough that it gets the correct power open loop.

To make things safe for your amplifier, I guess you would have to add an 
attenuator, so that maximum power will not overdrive the amplifier. 
However, I'm not sure that running at maximum power is good for clean 
signals.

I don't know if there is any open loop control between the power control 
and the transmit gain, or whether it totally relies on closed loop power 
control.  Any open loop control would have to be a compromise, because 
of production spreads in the gain, so, on most instances, would end up 
too high, so as not to limit the maximum output.

I believe there is a gain calibration procedure on the K3 and K4, that 
allows those to make a reasonable open loop power setting at the start 
of a transmission.

-- 
David Woolley (owner K2 06123)

On 18/12/2023 22:42, Karin Johnson wrote:
> Has anyone ever figured out why the Elecraft K2, either base version or with
> KPA100 amplifier, has a pronounced
> power overshoot on the first syllable using SSB.  I did an internet search
> for this problem and did not find
> a lot of discussion about it.  Difficult to use an external high power
> amplifier as the amplifier may trip on
> excessive drive.  My Elecraft K2 works just fine on CW.