K2 headphone audio for sound card PSK31?

[Cathy James]

I ran some tests this evening with my K2 and my computer sound card and
HamScope software.  80 meters was not great, but it was open and there
were a number of QSOs going on.

The K2 was able to pick up signals and decode them quite well, and the
narrow filters really help block QRM.  (My RTTY filter bandpasses are
all over the place, though; I don't think I ever finished setting them
up after getting Spectrogram going.  Have to revisit that!)

However, the audio drive from the K2 is much less than from the DX-70TH
that I use as my primary digital mode rig.  Although the signals decoded
well, the traces on the waterfall barely showed even at fairly high
soundcard record volume settings.  With the DX-70TH plugged into the
sound card instead, the same signals were brilliant yellow and easily
found by eye.

What can I do to increase the audio output level of the K2 for sound
card purposes?

Cathy
N5WVR

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[g4ilo-2]

You can take the audio output from the external speaker socket at the back
of the rig.
You can feed the audio into the more sensitive mic input of the sound card.
You can do one of the mods that provides a volume-independent audio output.
I take mine from the KAF2 board, but if you don't have a KAF2 there are
other options.
--
Julian, G4ILO K2 #392
G4ILO's Shack: www.g4ilo.com

Cathy James <[hidden email]> wrote:

What can I do to increase the audio output level of the K2 for sound card
purposes?


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[Jack Smith-6]

Cathy:

A trick I've used in the past with RTTY demods is to drive the demod
audio input (or sound card) via a step-up audio transformer.

In the days of tube-type demods, I would connect a tube-type audio
output transformer backwards across the receiver speaker output, but
that would produce too much voltage for a sound card. However, a
transistor audio output transformer should be about right, something in
the 8 ohm : 200 ohm range.

Of course, you could do the same type of voltage amplification with an
op amp, but a transformer works well for this application.

Or, you could use the microphone audio input instead of the line input.
Plenty more gain there, and most computers have an auxiliary +20 dB gain
switch.

Jack K8ZOA

Cathy James wrote:

>
> I ran some tests this evening with my K2 and my computer sound card
> and HamScope software.  80 meters was not great, but it was open and
> there were a number of QSOs going on.
>
> The K2 was able to pick up signals and decode them quite well, and the
> narrow filters really help block QRM.  (My RTTY filter bandpasses are
> all over the place, though; I don't think I ever finished setting them
> up after getting Spectrogram going.  Have to revisit that!)
>
> However, the audio drive from the K2 is much less than from the
> DX-70TH that I use as my primary digital mode rig.  Although the
> signals decoded well, the traces on the waterfall barely showed even
> at fairly high soundcard record volume settings.  With the DX-70TH
> plugged into the sound card instead, the same signals were brilliant
> yellow and easily found by eye.
>
> What can I do to increase the audio output level of the K2 for sound
> card purposes?
>
> Cathy
> N5WVR
>
> _______________________________________________
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>
>

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[Don Wilhelm-3]

Cathy,

I really have not had any problem using the headphone output - I have always
found that the AF Gain control on the K2 could be advanced sufficiently to
overdrive the sound card line-in.

You may want to look at something like the K2 Fixed Audio Output that I have
on my website http://w3fpr.qrpradio.com . I have a few boards left, but no
kits.

As for setting up the RTTY filters, my recommendation is to set FL1 just
like the SSB filter, FL2 at 1.00, FL3 at 0.70 and FL4 at 0.40.  Center FL2
thru FL4 on 1000 Hz.  In operation, you use the VFO to place the desired
signal near 1000 Hz, then you can narrow the filters if a strong signal
comes into the passband and activates the AGC - reducing the receiver
sensitivity.  Running PSK31 with AGC off is often a better way to operate.
BTW - lock the transmit frequency in your software if you use other than the
FL1 filter to keep the QSO from creeping up or down the band due to slight
differences in the audio pitch between filters.

73,
Don W3FPR

> -----Original Message-----
>
> I ran some tests this evening with my K2 and my computer sound card and
> HamScope software.  80 meters was not great, but it was open and there
> were a number of QSOs going on.
>
> The K2 was able to pick up signals and decode them quite well, and the
> narrow filters really help block QRM.  (My RTTY filter bandpasses are
> all over the place, though; I don't think I ever finished setting them
> up after getting Spectrogram going.  Have to revisit that!)
>
> However, the audio drive from the K2 is much less than from the DX-70TH
> that I use as my primary digital mode rig.  Although the signals decoded
> well, the traces on the waterfall barely showed even at fairly high
> soundcard record volume settings.  With the DX-70TH plugged into the
> sound card instead, the same signals were brilliant yellow and easily
> found by eye.
>
> What can I do to increase the audio output level of the K2 for sound
> card purposes?
>
> Cathy
> N5WVR
>

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[Bernard Gaffney, N8PVZ/QRP]

I've noticed the same thing about audio level,
especially out of the headphone jack. The rear speaker
jack seems to provide a higher audio level, so you may
want to try that. While I've not looked at the
circuitry involved, my guess is that the headphone
audio circuit does some attenuation of the audio, to
help keep from blowing out your eardrums when a loud
static crash or other noisy/loud signal pops up.

One other thing, if you're using your PC's
on-mainboard built in soundcard, consider using a
dedicated soundcard. Even a low end Creative soundcard
is infinitely better than the built-in card. And of
course, go to the manufacturer's web page and download
and install the latest driver updates.

   72 de N8PVZ
     ---bernie
 


> -----Original Message-----
 <snip>
>What can I do to increase the audio output level of
>the K2 for sound card purposes?




 
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[Phil Kane-2]

On Tue, 14 Nov 2006 22:16:50 -0600, Cathy James wrote:

>What can I do to increase the audio output level of the K2 for sound
>card purposes?

 Others have made some suggestions but I'll add mine as responses
 to their postings:

 On Wed, 15 Nov 2006 07:41:57 -0500, Don Wilhelm wrote:

>You may want to look at something like the K2 Fixed Audio Output
>that I have on my website http://w3fpr.qrpradio.com . I have a
>few boards left, but no kits.

  I can second that suggestion...I have installed it in my K2/100
  and after my local builder ("I may look great but I don't see
  well") worked out a problem of a less-than-perfect wire-to-connector
  joint, I am super-pleased with it.

>Running PSK31 with AGC off is often a better way to operate.

  I've asked this before - how does one turn the AGC off in a
  K2/100?

On Wed, 15 Nov 2006 07:49:19 -0800 (PST), Bernard Gaffney wrote:

>One other thing, if you're using your PC's
>on-mainboard built in soundcard, consider using a
>dedicated soundcard. Even a low end Creative soundcard
>is infinitely better than the built-in card. And of
>course, go to the manufacturer's web page and download
>and install the latest driver updates.

  We find things out the hard way -- Windows XP will not
  recognize a separate soundcard unless the mainboard sound
  system is disabled.  This was not acceptable for my
  istallation.

  The way I worked around that is to use an iMic adapter that
  plugs into a USB port.  XP will then recognize that as a
  separate sound system and permit both to operate simultaneously.
  The iMic is readily available at places which casrry portable audio
  stuff.

On Wed, 15 Nov 2006 09:09:44 +0000, Julian, G4ILO wrote:

>You can take the audio output from the external speaker socket at the back
>of the rig.

  Prior to using Don Wilhelm's Fixed Audio Output option, that's
  what I did.

  I used a readily-available Y-splitter to pipe output to the
  iMic (USB "soundcard") and to an outboard computer "multimedia"
  speaker which had a volume control. That way I could use the
  K2 for both digital (silent) and regular hamming, and not have
  to adjust the K2's audio/RF gain controls back and forth.

--
   73 de K2ASP - Phil Kane
   Elecraft K2/100   s/n 5402

   From a Clearing in the Silicon Forest
   Beaverton (Washington County)  Oregon



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[Doug Person]

Usually disabling the built-in sound system in a PC is simple.  You go
into the BIOS configuration and select disable in the list of devices.  
Do this first, then plug-in your soundcard and you shouldn't have any
problems.

I do disagree with the statement that most built-in sound systems are
inadequate for PSK31.  I think that would be the exception rather than
the rule.  I have yet to find a built-in that has problems with PSK-31.  
I wouldn't want to attempt a Software-Defined Radio that relies on a
computer's built-in sound system.  But the performance requirements for
good PSK31 support is not all that demanding for modern PC's built
within the last 3 or 4 years.

Doug -- K0DXV

Phil Kane wrote:

> On Tue, 14 Nov 2006 22:16:50 -0600, Cathy James wrote:
>
>  
>> What can I do to increase the audio output level of the K2 for sound
>> card purposes?
>>    
>
>  Others have made some suggestions but I'll add mine as responses
>  to their postings:
>
>  On Wed, 15 Nov 2006 07:41:57 -0500, Don Wilhelm wrote:
>
>  
>> You may want to look at something like the K2 Fixed Audio Output
>> that I have on my website http://w3fpr.qrpradio.com . I have a
>> few boards left, but no kits.
>>    
>
>   I can second that suggestion...I have installed it in my K2/100
>   and after my local builder ("I may look great but I don't see
>   well") worked out a problem of a less-than-perfect wire-to-connector
>   joint, I am super-pleased with it.
>
>  
>> Running PSK31 with AGC off is often a better way to operate.
>>    
>
>   I've asked this before - how does one turn the AGC off in a
>   K2/100?
>
> On Wed, 15 Nov 2006 07:49:19 -0800 (PST), Bernard Gaffney wrote:
>
>  
>> One other thing, if you're using your PC's
>> on-mainboard built in soundcard, consider using a
>> dedicated soundcard. Even a low end Creative soundcard
>> is infinitely better than the built-in card. And of
>> course, go to the manufacturer's web page and download
>> and install the latest driver updates.
>>    
>
>   We find things out the hard way -- Windows XP will not
>   recognize a separate soundcard unless the mainboard sound
>   system is disabled.  This was not acceptable for my
>   istallation.
>
>   The way I worked around that is to use an iMic adapter that
>   plugs into a USB port.  XP will then recognize that as a
>   separate sound system and permit both to operate simultaneously.
>   The iMic is readily available at places which casrry portable audio
>   stuff.
>
> On Wed, 15 Nov 2006 09:09:44 +0000, Julian, G4ILO wrote:
>
>  
>> You can take the audio output from the external speaker socket at the back
>> of the rig.
>>    
>
>   Prior to using Don Wilhelm's Fixed Audio Output option, that's
>   what I did.
>
>   I used a readily-available Y-splitter to pipe output to the
>   iMic (USB "soundcard") and to an outboard computer "multimedia"
>   speaker which had a volume control. That way I could use the
>   K2 for both digital (silent) and regular hamming, and not have
>   to adjust the K2's audio/RF gain controls back and forth.
>
> --
>    73 de K2ASP - Phil Kane
>    Elecraft K2/100   s/n 5402
>
>    From a Clearing in the Silicon Forest
>    Beaverton (Washington County)  Oregon
>
>
>
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>
>
>  

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[Don Wilhelm-3]

Phil,

To turn the K2 AGC off, press the PRE/ATT and AGC buttons at the same time.
See the K2 manual (rev F) page 100.
73,
Don W3FPR

> -----Original Message-----
> >Running PSK31 with AGC off is often a better way to operate.
>
>   I've asked this before - how does one turn the AGC off in a
>   K2/100?
>
>
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[g4ilo-2]

So do I. The most important factor is to be able to turn off any "sound
enhancement" features.
--
Julian, G4ILO K2 #392
G4ILO's Shack: www.g4ilo.com

Doug Person <[hidden email]> wrote:

I do disagree with the statement that most built-in sound systems are
inadequate for PSK31.



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[Henrik Tuxen]

Hallo Cathy,
for what it is worth I build a small audio interface from PSK31 based on
the ideas from Don, W3FPR. You can find the result on
www.qslnet.de/dk1htx.

My ambition was to fit the thing inside the K2/100 without taking up
space required for options. I have to admit that it did cost me one or
two evenings before I finally got it right.

Vy 73 Henrik, DK1HTX

On Tue, 2006-11-14 at 22:16 -0600, Cathy James wrote:

> I ran some tests this evening with my K2 and my computer sound card and
> HamScope software.  80 meters was not great, but it was open and there
> were a number of QSOs going on.
>
> The K2 was able to pick up signals and decode them quite well, and the
> narrow filters really help block QRM.  (My RTTY filter bandpasses are
> all over the place, though; I don't think I ever finished setting them
> up after getting Spectrogram going.  Have to revisit that!)
>
> However, the audio drive from the K2 is much less than from the DX-70TH
> that I use as my primary digital mode rig.  Although the signals decoded
> well, the traces on the waterfall barely showed even at fairly high
> soundcard record volume settings.  With the DX-70TH plugged into the
> sound card instead, the same signals were brilliant yellow and easily
> found by eye.
>
> What can I do to increase the audio output level of the K2 for sound
> card purposes?
>
> Cathy
> N5WVR
>
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