[Elecraft] PSK31 on the K2

[Charles Greene]

John,

Elecraft recommends running the K2 at 5 watts output.  To avoid distortion 
caused by controlling power with the ALC, set the power knob at 10 watts 
and control power output by varying the audio input to the K2.  I set the 
power at 70 watts and control it at 30 watts with the audio level on my 
K2/100.  PSK31 works well on QRP;  I once worked a VK with 5 watts for over 
an hour using a vertical antenna.  Don't be tempted to up the power level, 
as the guy at the other end won't even notice it, but your finals amps 
will!  An external 10K pot on the audio input works best.  Using this 
method, the power output will vary with audio frequencies from 500 to 2000 
Hz, but a careful alignment using Spectrogram of the OP1 filter helps a 
lot.  Try to keep the frequency response as flat as possible  from 500 to 
2000 Hz.  The Rev B K2 filter is much better than the original in 
flatness.  On my K2 462, the power output used to vary 6 dB over the audio 
from 500 to 2000 Hz, but now with the Rev B and other SSB mods, the output 
only varies from about 4.5 to 5 watts over the audio spectrum from 500 hz 
to 2000 hz.  Set K2 menu entries on SSBA to 1 and SSBC to 2-1.

Set the other filters, FL2, FL3 and FL3 at all at 1000 Hz center 
frequency.  You can go a little higher or lower, but you will not be able 
to set them much higher, and there are disadvantages for setting them 
lower.  A careful setting of the filters will result in a frequency offset 
between the transmitter which always uses OP1 and the selected filter in 
the receiver of 20 Hz or less.  The frequency jump is caused by steps in 
the voltage from the  D/A converter used to change the BFO frequency, and 
that varies a little based on whatever, so it's impossible to get them much 
closer.  For example, I can set a couple of filters to within 3 Hz of each 
other, but the next day they will be farther apart.  One filter always 
seems to have a frequency offset near the 20 Hz maximum.  Fine RIT will 
help minimize the frequency offset, but you can get around it by unlocking 
the transmitted audio frequency from the received audio frequency using the 
PSK31 program, after you make contact.

There are a lot of good software packages out there.  Digipan is a good one 
to start with, and it's free.  Its big brother, MixW written by the same 
programmers, adds lots of bells and whistles and includes most known 
digital modes, costs $50 registration to register.  I paid the fee in 1999, 
and am still getting free updates.  It has CAT which is a very nice 
feature, and controls everything that can be controlled on the K2 using CAT.

You can easily find the web sites for all software mentioned by doing a 
search using your favorite search engine.

I hope I have not overwhelmed you by all this.  The digital modes are 
FUN!  Any questions, ask, and someone will answer them.

GL and 73,  Chas, W1CG

At 03:38 AM 1/24/2004, John (KI7V) wrote:
>Hello all.
>
>I'm considering ordering the SSB module for my K2 - not for SSB but for
>PSK31.  Any experience out there with how well digital modes work with the
>SSB option for the K2?  In addition, any suggestions on PSK31 software?
>
>Thanks,
>
>73s,
>John - KI7V
>K2 #3706
>