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K3 Operating Tip: Setting up for PSK and other digital modes

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Greg - AB7R

K3 Operating Tip: Setting up for PSK and other digital modes

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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Bill VanAlstyne W5WVO

Re: 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
>
>
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

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Greg - AB7R

RE: K3 Operating Tip: Setting up for PSK and other digitalmodes

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:[hidden email]]
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:

Ian Maude

Re: K3 Operating Tip: Setting up for PSK and other digital modes

In reply to this post by Greg - AB7R

Greg wrote:
> Setting up your K3 for PSK (and other audio-based digital modes)
>
>
Many thanks Greg. Like a lot of things, it looks so easy when you know
how :)
One thing that threw me was that I assumed (yes I know, assume makes an
ASS of U and ME!) that the mic gain was the same in ssb and data modes.
I never thought to turn it up! For those of you who have not seen this,
in data mode, the mic gain (if data is set to line) is completely
separate to the ssb mic gain, it now works as a line volume. I am not
sure this is clear enough in the manual.

73 Ian

--

Ian J Maude, G0VGS
SysOp GB7MBC DX Cluster
Member RSGB, GQRP
K2 #4044 |K3 #455

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