Re: Dealing with FT8 interference on 20m #FT8 #qrm #lsb #20m

Graham
 

Most side band filters are  asymmetric,  with  sharp cut to the carrier  frequency  and a lesser slope to the  higher/lower cut  off  frequency ,

Or,  as racal did  with the  ra6790 and move the  oscillators about , whilst using the  3.4k am  symmetrical filter , unless  lsb/usb where  fitted  

Seems of of  over run quite a lot of bandwidth, stark contrast to the  time  Andy and myself spent , scouting clear spots to  run, the then new, opera system,  granted its only 1 or  2 Hz wide , but the  decoder pass  band is a couple  of  hundred Hz  on  most bands  , less on the  lower bands ,  +/- 50 Hz on 136 K 

73-Graham
g0nbd

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