> Narrow   IF filters  are  not  desirable  and   reduce the 
> performance of the  demodulator  , better  simply  use  SSB  filter
> GL ..73 -G..

Graham,

Why is that the case? What does the considerable extra bandwidth 
achieve? Is the SSB bandwidth optimal, or would it be even better 
with 10kHz bandwidth, or 100kHz?. Why is 3kHz better than perhaps 
1kHz or 2kHz? 

At first glance it appears crazy to let in all sorts of adjacent 
channel QRM (the bandwidth is more than ten times the size of the 
entire Opera window) when using a mode that occupies a fraction of 
1Hz.

Is it simply that the 1.7kHz Tx tone is high enough for the SSB 
filter to kill its harmonics, and on receive it is difficult to get a 
1.7kHz tone out of a CW filter, even with passband shifting. 

Am I missing something?

73 de Mike, G3XDV
g3xdv.blogspot.co.uk
================