FW: [Icom] Icom 756 IF filter
Dana Hoggatt
[email protected]
Tue, 16 Jul 2002 09:15:21 -0500
If you find that the FL-223 / FL-222 is too harsh, odds are
that you won't like FL-223 / FL-44a either. As you already
have the filters, try out FL-223 / FL-96 first and see what
you think. You may find that the FL-223 is the harsh filter.
Likewise, you can try out FL-80 / FL-222 to see how that sounds.
You'll learn a lot from those two experiments.
Many regard FL-80 / FL-44a as the optimal Icom filter combination
for SSB work, with good reason. For normal operation, you
can't go wrong with this combination.
If selectivity is your goal, then shape factor is definitely
important. The superior shape factor of the Inrad 109 should
make it a better drop-in replacement for the FL-44a.
For narrow SSB work, some are getting excellent results with
Inrad 110/314 filters (2.1KHz). They are tighter than the FL-80
/ FL-44a pair and have better shape factors without being as
narrow as the FL-223 / FL-222. Unfortunately, while the the
314 is a drop-in replacement, the 110 is not (you'll have to
wire it in). That is an obstical for some of us.
Finally, a warning. The true test is your ears. Some people
simply don't like the sound of narrow filtering. You could
be one of them. Also, the results are partly dependent upon
the transmission properties. The more band limited the signal,
the less "harsh" the results will be.
Good luck.
Dana, KB9SSS
On Jul 16, 10:28am, "Siu Johnny" wrote:
} Subject: Re: FW: [Icom] Icom 756 IF filter
}
} I currently install both FL223 and FL222 for my IC756. However, while the
} selectivity has been improved, the sound quality is harsh and sometimes
} difficult to listen.
}
} I note that under normal setting the two IF filters in IC756 are FL80
} (2.6khz) and FL96 (2.8khz) respectively. The 455khz filter has a wider
} band width than the 9mhz filter.
}
} Can I adopt the same approach for 'narrow' setting? i.e. FL223 + FL44A.
} Will this strike a balance between selectivity and sound quality?
}
} I also note some comments from the email reflector that filters from INRAD
} are better than those from ICOM. How true is this statment?
}
} Looking for your advice and thank you in advance.
}
} 73
}
} Johnny Siu VR2XMC
}
}
}
}
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}-- End of excerpt from "Siu Johnny"