[Elecraft] K3: FSK-D vs AFSK

[Don Wilhelm]

Jim,

It all depends on your software application(s).  If you are using the K3 
Utility display, then the only practical choice is FSK-D.  If you are 
using MMTTY, you have your choice between AFSK and FSK.  FSK will 
require a "one transistor keying circuit", while AFSK requires 
connection to your computer soundcard.
AFSK is used like any other digital mode - set the audio level to 4-5 
bars on the K3 ALC meter, and you will achieve copyable transmit by the 
other end.  If instead, you construct the FSK keying device and use 
FSK-D, there is no worry about audio levels.  The end result is the 
same, the receiving station can tell no difference.

If you are doing other digital modes, you probably have the soundcard 
connection to the K3 in place, and AFSK will be a natural extension, but 
if your data mode operation is restricted to RTTY, you may find the 
FSK-D selection more to your liking.

73,
Don W3FPR

On 10/12/2011 9:34 PM, Jim Miller wrote:
> I played a bit with FSK-D and AFSK today. I was able to get FSK-D to decode
> and display on the PC via the K3 Utility Terminal tab.
>
> While listening to T32C working a split RTTY pack I realized that trying to
> figure out which was the most recent worked station was a bit more difficult
> than doing it for CW, especially since the UP distance was 8-9Khz.
>
> I thought AFSK and display of the sigs on the PC screen might be of benefit
> but after putting it all together I realized that the bandwidth of the audio
> out would limit the spectrum to less than 4Khz.
>
> So what's the benefit of AFSK over FSK-D?
>
> Any suggestions for finding the last station worked in a pack?
>
>