[Elecraft] K2 SSB behaviour ?

[Ron D' Eau Claire]

> I'm a little bit puzzled with the SSB behavior of the K2!  It
> looks like it
> needs different audio drive levels on the different  bands to have the
> bargraph indication going up to the  actual CW power level. I also barely
> see an
> ALC indication using SSbA 3/SSbC 2:1. I have 8 watts CW into a
> dummy load on
> all bands
> but SSB power out and ALC is much different indicated on some bands (i.e.
> 10m). This seems to be dependent with the audio frequency also. A
> high tone
> whistle acts different on some bands as a low tone Ahhhhh.  I just use the
> bargraph indication for these observations.
>
> Is this a ALC problem ???
> Gerhard Kmet

That's perfectly normal operation Gerhard. The ALC adjusts the audio level
to produce the requested RF power output as measured at the antenna
terminal.

The overall r-f gain of the transmitter is different for different bands,
tending to be lowest on 10 meters. So on those bands, like 10 meters, where
the transmitter r-f strip overall gain is lowest, more audio is needed to
drive the transmitter to full output. This shows up as LESS ALC action on
those bands.

On other bands like 40 or 80 meters where there is a LOT of gain in the r-f
stages of the transmitter, you will see the ALC kicking higher, since it
must turn down the audio level more in order to avoid excessive r-f output.

It's very common to see just one bar of ALC action, barely, on 10 meters and
see several bars of ALC on 40 or 80 meters.

Of course, you should see full r-f output on all bands if your mic has
enough output. The r-f bargraph display is 'peak reading' so it will show
you what the actual peak SSB output is, while many external power meters are
average reading and show a much lower r-f output depending upon the audio
waveform.

Ron AC7AC
K2 # 1289