[Elecraft] PSK-31

[Ron D'Eau Claire]

If you have the SSB module in your K2 and a PC with a sound card, =
getting on
PSK31 is a matter of less than $15 if you buy everything you need brand =
new.


Since you said PSK31 was a favorite mode, I assume that you are equipped
with a suitable PC and software.=20

You need to connect the audio output of your K2 to the sound card input. =
A
simple male-male audio cable with 1/8 in stereo plugs will do this. Run =
it
between the headphone output and sound card "line" input. I have a =
little
Radio Shack adapter with a single male plug to two female jacks that =
allows
me to plug in my phones in parallel with the computer. That way I don't =
have
to listen to the audio through the computer sound card if I want to =
monitor
what's going on by ear.=20

You need to connect the output of your sound card to the audio input of =
the
K2. The audio input of the K2 is designed for low-level "mic" signals. =
You
can't hook the sound card up directly without being in serious danger of
over-driving the K2, picking up noise from the computer audio system, =
etc.
You need an attenuator that will reduce the audio level coming from the
computer to about what a microphone delivers to the K2. Radio shack and
others sell a cable with a built-in attenuator that will do this. The =
cables
are intended to connect a "line" input into a "mic" input of a recorder. =
You
can make a cable too, since you will need the special mic connector at =
the
K2 end. Radio Shack sells the mating 8-pin connectors for the mic input. =
You
will need a large resistor - about 100 k ohm and a 5 k ohm resistor to =
form
the attenuator. 1/4 watt (or even 1/8 watt, if you have them in the =
junque
box) will be fine. The 5 K goes from the mic pin to ground. The 100 K =
goes
in series with the audio coming from your PC. That will cut down your =
line
audio enough to avoid over-driving the K2 mic input.=20

Finally, you need to be able to switch the K2 from receive to transmit. =
I
added a small toggle switch right at the connector that goes on the K2 =
"mic"
jack. Flip it one way, and it grounds the PTT line to put the K2 in
transmit. Flip it the other way and it releases the PTT to put the K2 in
receive. Since a PSK 31 exchange takes a couple of seconds to switch =
over
anyway, flipping the switch is not a bother for me and it does not hold =
up
the QSO.=20

Of course, you can spend $100 or more and buy a box that does the PTT =
action
automatically using commands from your PC's RS 232 port. And it'll have =
a
built in attenuator for the mic input,  but you said you wanted to keep =
the
price down. You can build your own solid-state T/R switch too. It's not
hard. I opted for the simple method that didn't require another cable.=20

When you work PSK 31, be sure the K2's ALC system does NOT engage. The
easiest way to do that is to set the POWER control for 10 watts, then
increase the audio from the computer until the actual power shown on the =
K2
bar graph (or on an external wattmeter) is 5 watts. By keeping the POWER
control set well above the actual power output, you will not let the ALC
engage. That prevents some distortion from occurring.=20

Have fun!

Ron AC7AC
K2 # 1289

-----Original Message-----
Some of you may have read my post where I was going to sell my =
unfinished
K2. I want to thank those of you who talked me out of it. Due to lack of
time etc etc I'm having it finished for me! At least I can say I built =
over
half of it, and I'm excited now that its being finished.

Ok, one of my favorite modes and the one I use the most is PSK-31. For =
those
of you who are using K2's on this mode what is the easiest way to get on
PSK-31 with the K2? My spare change kitty is darn near broke so it has =
to be
fairly cheap!

Jerry - NR5A