[Elecraft] K2: PSK-31 Power Settings

[Don Wilhelm]

Jon,

I would recommend setting the power to 30 watts.  Then hold DISPLAY to 
change the metering to ALC - adjust the audio up just to the point where 
there is no ALC indication (adjust until you see ALC bars and then back 
off until there are none).  That should give you a cleaner signal and 
better control of the output level.  Since the gain of the K2 transmit 
chain varies from band to band, you may have to check the audio drive 
level again when changing to a different band.  For further explanation, 
read on.

For those using the K3 instead of the K2, set the audio to indicate 
between  4 and 5 bars on the ALC meter - the low end of the "ALC meter" 
scale on the K3 does not indicate ALC at all, but is more like a VU 
meter - ALC action starts at the 5th bar.  Let the K3 control the power 
out with its normal control mechanism.

The K2 and K3 control power in a different way than many other 
transceivers, in that they monitor the level of the output signal, and 
if that level is less than the level requested, the drive will be 
increased in an attempt to increase the power.
So the likely result of you setting the K2 power to 100 watts and using 
the audio level to control the power results in the K2 trying to 
increase the drive to make the peaks as close to 100 watts as possible - 
of course, it can't make it because you have decreased the audio. but 
using the K2 that way will increase the residual level of the suppressed 
carrier and cause other parameters of the normal power control mechanism 
to "do strange things".

Theoretically, the audio level should be able to control the SSB power 
output, but also in theory, the suppressed carrier would be zero.  In 
reality, there is a bit of residual carrier, and that is what messes up 
doing things "by theory".  Controlling the audio alone will work just 
fine in a transceiver which controls the output level by adjusting the 
drive at some point *beyond* the BFO injection to the balanced 
modulator, but the K2 uses the BFO injection to control the power output.

73,
Don W3FPR

Jon Perelstein wrote:
> This may have been answered before, but I couldn't find any search terms that brought up the info I was looking for.
>
> What power and volume settings do people use for PSK-31?
>
> I have a 100w K2 and I use a SignaLink going into the K2's mic jack.  The standard approach that has always been recommended to me is to set the rig's power to full power and then control output power with the transmit volume setting on the SignaLink.  I set my SignaLink transmit volume so that the RF level on the K2 shows about 30 watts (essentially 3 tick marks) when I'm transmitting.
>
> I've noticed that the K2 gets very hot this way, with the fan going to high high speed. 
>
> Is that the right way to run the K2, or should I be doing something differently?
>
> Thanks.
>
>