Well ... I'm not sure FSK is actually "foolproof," based on the number of posts to this list about problems getting FSK running using various external interfaces. It is true that AFSK is "Audio in/out" and can overdrive things, not easy in a K3 but certainly possible. Even cheap sound cards deliver essentially pure sine wave audio, the better ones do even better.

One should never underestimate the populations' ability to screw up any technology, but beyond that, and assuming that two hams are equally smart and equally adept at setting their gear up, is there really any discernable difference between the two methods with a K3? I think that's my root question -- "What is it about direct FSK that makes folks want to go to lengths to get it working?" And, I'm not so sure that "direct FSK" in a K3 is what it was in a T-368 45 years ago.

I grant that with older rigs, carrier and opposite sideband suppression could, being generous here, be questionable, and the AFSK result would not be pretty. But that was a long time ago and we're talking about K3's now.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2014 Cal QSO Party 4-5 Oct 2014
- www.cqp.org

On 3/24/2014 4:33 PM, Wes (N7WS) wrote:
FSK might not have "excess" bandwidth, but AFSK can have narrower
bandwidth.

http://www.frontiernet.net/~aflowers/k3rtty/k3rtty.html#K3_AFSK_filter


On 3/24/2014 5:27 AM, Barry wrote:
Fred,
If set correctly, there's no difference.  However, FSK is foolproof.  It
can't be overdriven with excessive audio input resulting in excess
bandwidth
and spurs.  Some of it is historical, as in some older radios, narrow
filters cannot be used in AFSK mode.
Barry w2UP


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