[Icom] Filtering at 9 MHz vs. 455 kHz

[Donnie Garrett]

Rick:
I have had both and the 455 Khz works best.   73''s Don / WA9TGT

----- Original Message -----
From: "Clifford, Rick" <rick.clifford@eds.com>
To: <icom@mailman.qth.net>
Sent: Friday, September 13, 2002 1:32 PM
Subject: [Icom] Filtering at 9 MHz vs. 455 kHz


> ICOM'ers,
>
> I have an IC-746 (original, not PRO) and do primarily CW on 40m. After
> suffering through several instances of adjacent frequency interference, I
> decided to buy a filter. The IC-746 has two places where filters can be
> placed, the 9 MHz and the 455 kHz IF stages. So now I needed to find out
> which 500 Hz filter to buy. The suggestion from the HRO store was to
filter
> at the 455 kHz stage (naturally, the more expensive of the two options),
> while a call to ICOM suggested that both stages should be filtered (an
even
> more expensive option).
>
> I ended up installing the more expensive ($180) 455 kHz filter (500 Hz
> bandwidth). I am quite pleased with the performance, but wonder if I will
> get significantly improved filtering performance if I also place a 500 Hz
> filter in the 9 MHz IF stage.
>
> Since I have been wondering what the 250 Hz filter is like, an alternative
> approach is to buy the 250 Hz filter and put it in the 9 MHz stage. Then,
I
> should be able to switch in either 250 or 500 Hz.
>
> Does any have an opinion about how these filters should be used across the
> two IF stages? And, is there enough difference between the 250 Hz and 500
Hz
> filters to justify having both?
>
> Thanks and 73,
>
> Rick
> KF6UEB
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