[RTTY] 300hz or 500hz IF filter?

[Bill Turner]

ORIGINAL MESSAGE:          (may be snipped)

>You are just simply wrong. And in any case the question was about 
>filters not the signal.  Been using stacked 250 Hz filters for over 30 
>years on Icom, Kenwood, Yaesu radio's.  They simply work in RTTY 
>contesting always have and always will.  Theory, math, which I trust 
>Chen on far more than I believe you may indicate something else but 
>experience tells me narrow is better for contesting,  perhaps wider for 
>weak signals but if they are that weak most won't hear them at all 
>during a contest which is why DXing if different from Contesting.

REPLY:

Jay has summed it up well. Practical, on the air testing is always the best.
Theory can point in the right direction and might save some time, but the
acid test is on the air. 

For example, I operated RTTY for years with an IC-756Pro3 using a 250 Hz
filter and it was very satisfactory. About two years ago I upgraded to an
IC-7600 and set it to 250 Hz as well. I was quite disappointed in the copy.
Even on strong signals, there were many errors in the print.  On a hunch, I
widened the filter out to 300 Hz and reception returned to satisfactory. The
difference was the '7600 had steeper skirts than the 'Pro3. The point is,
just stating an "optimum" filter bandwidth is too simplistic. It depends on
other variables. 

Theory helps, but "cut and try" will give the final answer. 

73, Bill W6WRT