FW: [Icom] Icom 756 IF filter

Mon, 15 Jul 2002 19:42:51 -0700

Hi Johnny,

To answer your question: I had an IC-756 in which I installed the FL-222/223
pair. They improved adjacent-channel selectivity dramatically, at some cost
in recovered audio quality. But when one needs that extra filtering, some
sacrifice in audio quality is usually acceptable.

You might consider replacing the stock FL-96 with an FL-44A. This will
tighten up Twin PBT and adjacent-channel selectivity in the normal SSB
filter setting. Then you can use the filter menu to pair the FL-223 with the
FL-44A or the FL-222, as required by band conditions. (Twin PBT only works
well when the filter bandwidths are reasonably well matched).

The Inrad 109 is electrically and mechanically compatible with the FL-44A;
the 322 with the FL-222. They have somewhat better shape factors. See
http://www.qth.com/inrad/

I do not always recommend using the Inrad 9 MHz filters, as they are not
mechanically compatible with the Icom filters.

Best 73,
Adam, VA7OJ/AB4OJ
North Vancouver, BC, Canada
http://www.qsl.net/ab4oj/
Note new e-mail address:
mailto:[email protected]

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Siu Johnny
Sent: July 15, 2002 19:28
To: [email protected]
Subject: Re: FW: [Icom] Icom 756 IF filter

Hi Adam,

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