[Elecraft] K3 Operating Tip: Setting up for PSK and other digitalmodes

[Greg]

Bill,

I'm using a similar setup and I don't notice any issues.  Though I've not
used FSK441 before.

I have a MicroHam MK2R+ connected to the K3 and it also has built-in sound
codecs with transformers.  Works fine for AFSK and PSK.

73
Greg
AB7R

-----Original Message-----
From: Bill W5WVO [mailto:w5wvo at cybermesa.net]
Sent: Sunday, March 02, 2008 6:28 PM
To: Greg; Elecraft Reflector
Subject: Re: [Elecraft] K3 Operating Tip: Setting up for PSK and other
digitalmodes


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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