K2 & Aux Digital Mode Connection Box

[lbailey]

Anybody have any experience with the various auxiliary connection boxes
for running digital modes with your K2 & software from your PC.  Comments?
 Suggestions?

73, Lynn, K5AVJ
K2 #1411
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[Leigh L. Klotz Jr WA5ZNU]

If you take the audio directly off the AF gain pot, you will pick up
shack noise through microphonic action of the speaker or headphones.
On Sun, 29 May 2005 7:14 am, [hidden email] wrote:
> Anybody have any experience with the various auxiliary connection boxes
> for running digital modes with your K2 & software from your PC.  
> Comments?
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[Nigel A. Gunn G8IFF/KC8NHF]

And how exactly is audio from the speaker going to travel BACKWARDS
through the audio amplifier?

Leigh L Klotz, Jr. wrote:

> If you take the audio directly off the AF gain pot, you will pick up
> shack noise through microphonic action of the speaker or headphones.


--
<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
Nigel A. Gunn. 59 Beadlemead, Milton Keynes, MK6 4HF, England.
Tel [phone]
e-mail [hidden email] or  [hidden email]
www    http://www.ngunn.net  or  http://www.ngunn.demon.co.uk
Amateur radio stations  G8IFF, KC8NHF
Member of  AMSAT-UK #182, ARRL, GQRP Club, QRPARCI, SOC #548  RAYNET
           Flying Pig #385, Dayton ARA #2128, AMSAT-NA  LM-1691,
<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>


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[Don Wilhelm-3]

Lynn,

While I have not used any of the commercially available connection boxes,
you may want to glean some ideas from my homebrew stuff - Fixed Audio Output
for the K2 and A Switchbox for Digital Modes - documented on my website at
www.qsl.net/w3fpr and mirrored at http://home.earthlink.net/~w3fpr.  The
transformers salvaged from defunct PC modems make fine isolation
transformers between the computer soundcard and the rig.

73,
Don W3FPR

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]]On Behalf Of [hidden email]
> Sent: Sunday, May 29, 2005 10:16 AM
> To: [hidden email]
> Subject: [Elecraft] K2 & Aux Digital Mode Connection Box
>
>
> Anybody have any experience with the various auxiliary connection boxes
> for running digital modes with your K2 & software from your PC.
> Comments?
>  Suggestions?
>
> 73, Lynn, K5AVJ
> K2 #1411
> _______________________________________________
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> Post to: [hidden email]
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[Leigh L. Klotz Jr WA5ZNU]

Nigel,
I am seeing thr phenomenon I described, but you must right, as I am
taking the output after the amplifier, and that is likely not on the AF
gain pot, so I was probably wrong citing the tap location.  I don't have
access to my schematics or a PDF viewer right now.

I tried taking the output before the amplifier, but it wasn't high
enough level for my sound card, and I was troubled by noise on the low
signal.  So I moved the tap to after the audio amplifier and that is
where I am seeing the audio pickup from the speakers.

I did buy one of Don's digital out boards, but didn't install it yet.  
Someday...

73,
Leigh / WA5ZNU
On Sun, 29 May 2005 11:07 am, Nigel KC8NHF/G8IFF wrote:

> And how exactly is audio from the speaker going to travel BACKWARDS
> through the audio amplifier?
>
> Leigh L Klotz, Jr. wrote:
>
>> If you take the audio directly off the AF gain pot, you will pick up
>> shack noise through microphonic action of the speaker or headphones.
>
>
> --
> <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
> Nigel A. Gunn. 59 Beadlemead, Milton Keynes, MK6 4HF, England. Tel +44
> (0)1908 604004
> e-mail [hidden email] or  [hidden email]
> www    http://www.ngunn.net  or  http://www.ngunn.demon.co.uk
> Amateur radio stations  G8IFF, KC8NHF
> Member of  AMSAT-UK #182, ARRL, GQRP Club, QRPARCI, SOC #548  RAYNET
>           Flying Pig #385, Dayton ARA #2128, AMSAT-NA  LM-1691,
> <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

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[Bill Coleman-2]

On May 29, 2005, at 10:15 AM, [hidden email] wrote:

> Anybody have any experience with the various auxiliary connection  
> boxes
> for running digital modes with your K2 & software from your PC.  
> Comments?
>  Suggestions?

I recently built such a box that I could use with CocoaModem, a  
RTTY / PSK program for MacOS X.

My unit is pretty simple, and only took me an evening to build. I use  
a 600:600 ohm transformer and a 8:1000 ohm transformer. The 8:1000  
transformer goes between the headphone jack (8 ohm side) and the mic  
input on the computer. The 600 ohm transformer connects between the  
computer output jack and the microphone. This allows complete ground  
isolation between the computer and the K2.

I use a couple of 25 ohm resistors as loads for the computer  
headphone output, and I have a 500 ohm fixed and 5000 ohm variable  
resistor so I can adjust the level into the microphone. I use just  
barely enough audio to keep the VOX positively triggered.

If you use a program with a positive PTT output, I would use that  
(through an optoisolator) instead of VOX -- then you can run even  
lower audio levels, which result in less distortion.

Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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