[Elecraft] [K3] Soundcard digital mode follow-up

[Jim Brown]

On 7/6/2011 12:45 PM, Don Putnick wrote:
> I was using the K3 in DATA A mode with the stock 2700 roofing filter. No attenuation, preamp, or noise reduction. I connect the LINE IN and OUT to my MacBook's External Speaker and Mic. I use cocoaModem software for PSK31. I was going after weak traces in the presence of 1-3 band hogs. My first reaction was to do exactly what Don Wilhelm suggested. I reduced the DSP filter to 400 Hz, but when I did that, the waterfall saturated.

What do you mean saturated?  What SHOULD happen when you narrow the 
bandwidth is that you should see fewer signals.

>   Knowing from a propagation analysis that it was very unlikely I'd be successful anyway, I gave up.
>
> Here are the suggestions I received, the last three in combination with the first two.
>
> 1. Decrease the DSP filter bandwidth

Yes, but also tune the IF up or down  so that the IF filter favors the 
signal you're trying to work. .(Or retune the main dial -- there's 
nothing "magic" about setting to 14070, or whatever.

> 2. Buy a narrow roofing filter for digital modes

Yes, but probably necessary only in heavy contesting or DX pileup 
conditions.

> 3. Reduce LIN OUT level

YES.
> 4. Turn Attenuator on

Maybe, but certainly turn off the preamp.
> 5. Turn AGC off

Try turning down the RF gain a bit.