[Elecraft] [K3] Attenuator and soundcard digital modes

[goldtr8 at charter.net]

Hi Don,

I concurr with Don on his analysis.

I have a 700hz and 200 hz filter and I use them quite a bit for PSK31. 
If you try to use just the DSP to narrow down the bandwith it does not 
work as well.  I used to only have a 2.7 and 2.1 k hz filters and used 
the DSP only.  However after using the narrow filters my receive on weak 
signals has improved a lot.

Now on the transmitt side of things there are many times that even 
thought I can hear them I am not able to work them.  Part of this is 
probally due to my receive being more efficient than my TX with my 
dipole.

Also are you using Data A mode and not SSB.  Plus you need to turn off 
much of the noise reduction to make PSK work.

I find that I have to go to between 30 and 40 watts to make contacts 
with my K3 and dipole.

I tried to work some of the special events but only got one on PSK and 
one SSB, but I did not try very hard.  Plus they had a lot of traffic.

Hope this helps

Now its Don Cubed!

Don
KD8NNU


On Tue, Jul 5, 2011 at 8:02 PM, Don Wilhelm wrote:

> Don,
>
> What is your specific problem?  If it is strong signals within the 
> passband, then more narrow roofing filters are the answer.  Instead of 
> using the entire 2.7 kHz bandwidth and depending on the software 
> application to resolve any one signal, use the K3 filtering to zero in 
> on a specific signal, and you will find the decoding much better, with 
> or without the presence of noise.
>
> Yes, what I am suggesting is that you first reduce the bandwidth of 
> the K3, and then the PSK31 software has fewer signals to deal with, 
> and can decode them better.
>
> I know that most PSK31 operators just use the full SSB bandwidth and 
> let the software resolve the signals.  While that works when all those 
> transmitting PSK31 keep their power down to a reasonable level, there 
> are those few who insist on being "band hogs", and transmit at 100 
> watts plus.  PSK31 can be very effective when used at 15 to 25 watts, 
> and many do keep it at that - but Special Events and contests, I find 
> that some crank up the power, and decoding for everyone else on the 
> band suffers.
>
> The K3 with its roofing filter selection and DSP filtering can help 
> greatly, but to take advantage of that, one must reduce the bandwidth 
> of the K3, and that means not using the full spectrum waterfall 
> display -- use the K3 VFO to move from signal to signal, and your 
> decoding will be greatly improved.
>
> 73,
> Don W3FPR
>
> On 7/5/2011 7:39 PM, Don Putnick wrote:
>> After having a less than successful time with PSK31 during the 13 
>> Colonies Special Event, I think I need to learn more about noise 
>> reduction. I've read the section in KE7X's manual, but I'm looking 
>> for guidance specific to the soundcard digital modes.
>>
>> 1) It appears the K3's attenuator is fixed at -10 dB. Is that the 
>> case or is it reprogrammable?
>>
>> 2) What is the collective wisdom on noise reduction for soundcard 
>> digital modes: K3 attenuator, K3 noise reduction, PSK31 software 
>> noise reduction, some combination of the three, or none at all?
>>
>> Thanks and 73,
>> Don NA6Z K3 #5495
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