Nice summary, thanks Greg. I'll be using the K3 digitally for the WSJT modes
on 6 meters, among others. Here's a question that occurred to me today:
I am probably going to be using the SignaLink USB (built-in sound card /
codex). This unit also has built-in 600-ohm isolation transformers -- as does
the K3. Is there any problem presented by having two sets of transformers in
the line? I worry that if the quality of both transformers isn't really good,
the transformers could introduce nonlinear delay or amplitude characteristics,
especially in modes like FSK441 which use a fairly wide range of audio
frequencies. I'm sure the K3 transformers are the best, but I know nothing
about the SignaLink -- and having two transformers in each line concerns me a
little.
Bill W5WVO
Greg wrote:
Setting up your K3 for PSK (and other audio-based digital modes)
The K3 is an outstanding platform for operating digital modes. It
already has dedicated direct FSK and PSK with your CW paddles. But
there is also an option to use Data-A mode to operate PSK or any
other audio based digital mode in conjunction with soundcard-based
digital mode software.
It is usually best to use a second soundcard for your audio-base
digital modes. This way you will not be plagued with Windows sound
effects in your waterfall or in your transmitted signal. If you do
not have that option, you can always go into your Windows control
panel and open "Sounds and Audio devices." Select the Sounds tab and
set Sound Scheme to No Sounds.
Here are the steps to setup for PSK using Data-A mode:
1. Set your soundcard volume to about 50%.
2. Connect soundcard output to the K3 LINE-IN.
3. Connect the soundcard input to the K3 LINE-OUT.
4. Set Menu item MIC SEL to LINE IN. The K3 will remember this MIC
SEL source next time you use digital modes.
5. Set mode to DATA. HOLD DATA MD to choose Data-A using the VFO B
knob.
6. Set power to ~20W (just something to start with).
7. Use the MIC control to set the drive level so that your output is
equal or just below what you dialed in (20W in this case).
Compression is locked at zero automatically when in Data mode and
cannot be adjusted. You should not see any ALC bars on the K3
display (when set to CMP/ALC). When setup this way I get excellent
PSK31 results with TX IMD at ~ -26 dB to -32 dB - a very clean signal.
FOR PTT
You can use a separate line for PTT from a computer COM port to the
ACCY connector or the RCA PTT connection on the back of the K3. This
requires a simple circuit using a transistor and resistor between the
COM port and the K3. You can find this circuit on many ham radio
websites, including the AA5AU RTTY website (this will be a hyperlink
to http://www.aa5au.com/rttyinterface.html ). You can also use the
RS-232 serial connection if your software allows you to set it up
that way. Not all software allows you to do this. Some programs
will also allow PTT via CAT command.
In the K3 CONFIG menu, set PTT-Key to either RTS - OFF or DTR - OFF.
Then in your software set PTT to either DTR or RTS as appropriate to
the same COM port the radio is connected to.
------------
73,
Greg - AB7R
Whidbey Island WA
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