Re: K3 DSP Upgrade Correction

[Dick Dickinson]

"I use my system with Line with Speaker Out" - should read, 'I use my system
with Speaker out through a matching network to line in on my computer sound
card.'  The matching network is a $20 item from an auto sound store and is
used to cut speaker level down to line level.

 

 

73,

Dick - KA5KKT

 

 

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[Jim Brown-10]

On 3/22/2011 7:24 PM, Edward Dickinson III wrote:
> The matching network is a $20 item from an auto sound store and is
> used to cut speaker level down to line level.

You just spent $20 on something that you could have done equally well
with two 5-cent resistors, AND that probably was not needed in the first
place.

Study the part of http://audiosystemsgroup.com/HamInterfacing.pdf that
talks about audio levels.  Also see the Appendix on audio that is part
of http://audiosystemsgroup.com/RFI-Ham.pdf

The executive summary -- most computer sound cards clip at about 1 volt
sine wave. A 2-watt power amp, typical for ham gear, would clip at about
2 volts, and that only occurs on very loud audio peaks. All that's
required to prevent clipping of the sound card input is to turn the
speaker output gain down a bit.

A simple voltage divider (the two resistors) IS needed to drive a MIC
level input.

73, Jim K9YC


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[Don Wilhelm-4]

  Jim and all,

Some just have not "gotten it".  The K3 is soundcard digital ready.  
Just connect the computer Line in to the K3 rear panel Line Out, and the
computer Line Out to the K3 Line In, and set the "mic sel" menu for data
modes to Line In.

Yes, if you only have speaker out level from your computer (most have
line level out), then a resistive divider is in order - nothing exotic -
as Jim pointed out, two resistors will do the job.

73,
Don W3FPR

On 3/22/2011 11:01 PM, Jim Brown wrote:

> On 3/22/2011 7:24 PM, Edward Dickinson III wrote:
>> The matching network is a $20 item from an auto sound store and is
>> used to cut speaker level down to line level.
> You just spent $20 on something that you could have done equally well
> with two 5-cent resistors, AND that probably was not needed in the first
> place.
>
> Study the part of http://audiosystemsgroup.com/HamInterfacing.pdf that
> talks about audio levels.  Also see the Appendix on audio that is part
> of http://audiosystemsgroup.com/RFI-Ham.pdf
>
> The executive summary -- most computer sound cards clip at about 1 volt
> sine wave. A 2-watt power amp, typical for ham gear, would clip at about
> 2 volts, and that only occurs on very loud audio peaks. All that's
> required to prevent clipping of the sound card input is to turn the
> speaker output gain down a bit.
>
> A simple voltage divider (the two resistors) IS needed to drive a MIC
> level input.
>
> 73, Jim K9YC
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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[Tony Estep]

On Tue, Mar 22, 2011 at 10:49 PM, Don Wilhelm <[hidden email]> wrote:

> ...The K3 is soundcard digital ready....
>
> I'm so dumb that when I got my K3, I spent half a day fiddling with cables,
jumpers etc. to configure my digital interface box. Then suddenly the light
dawned! It was a happy moment when I disconnected the sound-card interface
box and all its cables and relegated the whole works to a box in the
basement.


Tony KT0NY
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