[Elecraft] k3/psk on laptop

[Joe Subich, W4TV]

> If you plan on a bit more digital work I strongly suggest an 
> external USB or Firewire soundcard. Laptops often have a rotten 
> soundcard, an external card can be amazing.

I hate to disagree with Simon but I do want to answer the old 
wives' tale about internal sound cards and laptops ... 

The issue with internal soundcards - both desktop and laptop is 
much more one of sensitivity than internal noise.  Many amateur 
transceivers have severely limited audio levels from their 
"line level" outputs - in some cases it can be as little as 
50 mV (-25 dBu) at 10k Ohms.  This is generally insufficient 
when driving the "600 Ohm" inputs of most soundcards. 

The problem with low input levels is that many inexpensive 
laptop and internal sound systems may have noise floors as 
high as -30 to -40 dBu due to poor bypassing and grounding 
of signals within the computer.  If such a soundcard is used 
with low drive and poor connections that result in external 
bum/buzz, the results will be poor.  

Fortunately, the K3 has plenty of drive and due to its ability 
to produce more than 1 volt RMS output is more than capable 
of obtaining excellent results with even a very noisy soundcard.   

One only need adjust the K3's Line Out level until the "no 
signal" noise from the K3 raises the noise floor as seen on 
a spectrum (not waterfall) display by 6 - 10 dB.  This will 
provide nearly 40 dB of dynamic range from even a "noisy" 
soundcard system.  The situation is far different with one 
of the radios that provides only 50 to 100 mV.  

73, 

   ... Joe, W4TV 
 





> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Simon 
> Brown (HB9DRV)
> Sent: Tuesday, June 10, 2008 1:10 PM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] k3/psk on laptop
> 
> 
> Don,
> 
> If you plan on a bit more digital work I strongly suggest an 
> external USB or 
> Firewire soundcard. Laptops often have a rotten soundcard, an 
> external card 
> can be amazing. Laptop soundcards are OK for Beep and Ding 
> but for digital 
> mode work they really can be the limiting factor.
> 
> The K3 has a stonking receiver, it's a shame to cripple it 
> with a laptop 
> soundcard.
> 
> Simon Brown, HB9DRV
> 
> --------------------------------------------------
> From: "Blachura" <haircutter at verizon.net>
> 
> > thanks for all the replys on the k3 and getting the digital 
> modes to work 
> > on
> > a laptop. 
> 
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