[Elecraft] K3: best roofing filter on RTTY

[Jim Brown]

On Mon,2/16/2015 2:38 PM, K4ia via Elecraft wrote:
> I attended Contest University at Dayton last year and the RTTY expert 
> suggested he found that too narrow a filter compromised the decoding.  
> It seemed to work best when the filter was a little wider.

That same expert used to recommend narrower filter and dual-peak IF. I 
always thought that was a bad idea on the basis of the additional phase 
shift introduced by the narrower filter and the dual peaks, but no one 
believed that until G3YYD, author of the new and very nice RTTY decoder, 
said so. :)

I have the 250 Hz 8-pole and 400 Hz 8-pole filters. I switch in the 250 
Hz filter at 350 Hz and the 400 Hz filter at 500 Hz. Most of the time, I 
set the IF to 400 Hz for RTTY and 250 Hz for CW. The only times I'll go 
narrower for RTTY is with very strong QRM very close to my frequency.

73, Jim K9YC