[VHFcontesting] Re: VHFcontesting digest, Vol 1 #201 - 12 msgs

Fred Lass fredlass at global2000.net
Tue Jun 18 20:49:39 EDT 2002

> Hi Joel;

> Generally, selectivity at a high IF tends to improve the nearby stong signal rejection characteristics of the receiver, but close-in skirt selectivity of
> high IF filters is usually not as good as low IF filters.  So, the best is to have both filters.  If you can only afford one filter, in my opinion, it
> should be the high IF filter.  The best system uses good skirt selectivity filters in both IF's.  This is why International Radio filters are used by
> serious contesters.

73,  Fred

> Message: 4
> From: "Joel N. Weber II" <kb1grs-vhfcontesting at vms.gratuitous.org>
> To: vhfcontesting at contesting.com
> Date: Sun, 16 Jun 2002 20:22:52 -0400
> Subject: [VHFcontesting] IF filter selection
> The club I'm involved in (w1xm) is looking into adding filters to our
> IC-746, which has never had any of the optional filters installed.  It
> has been the rig we use for 6m in the VHF contests, and we also have
> used it for HF for Field Day.  We do primarily SSB operation, as most
> members of the club aren't terribly proficient at CW operation, but
> there is one operator who frequently does CW, so we want to have
> filtering that is suitable for both modes.
> Which filters would be best to install?  I understand that the rig
> will take up to three optional filters, some of which have a 455 khz
> center frequency, and some which have a center frequency somewhere
> around 9 mhz.  I don't think I've ever come across much literature
> that explains in much detail why one would prefer one center frequency
> over the other, nor am I terribly clear on which bandwidths are best
> for SSB use.
> So I'm curious if the people on this list have thoughts on which
> filters would be the best to get, and why.
> (Another possibility that has been suggested is that perhaps replacing
> that rig with an FT-920 (or perhaps some other rig) would be
> worthwhile.)
> --__--__--

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