On Thu, Feb 27, 2014 at 9:21 PM, Richards <jrichards@k8jhr.com> wrote:
>
>
>
> Not sure I agree with some of the others who
> say roofing filters and etc. only matter in a
> contest or for CW. I an NCS for a weekly
> Brand X transceiver owner's net, and there are
> times when stations crowd us on either side of
> our usual net frequency, and sometimes it is
> easier to pare down the pass band with the filter
> scheme until I cannot hear them on either side.
> This happens a lot, actually, either from some
> guy having a super wide signal 3 MHz above us,
> or if he is just 1.5 MHz below us... and (of
> course) he is always loud. I am disinclined
> to slide up and ask him to QSY a skosh, so I
> just narrow the filters and drive on. I am sure
> there is a better plan...but that usually works
> for me.
>
> So, unless I misunderstand the point, I think
> these things do matter in more mundane circumstances
> than contesting and crowded CW conditions.
>
Not sure if you misunderstand or not. Carl already explained it
somewhere back in this thread. We're talking only about circumstances
that demand more than 80dB dynamic range at 2KHz spacing. That's
trying to read an s2 (or weaker) dx station on cw within 2KHz of an
s9+40dB (or stronger) signal. A roofing filter will do nothing for
super wide signals with rf in the desired passband - those can't be
removed. We're talking about signals that are VERY strong and close
in frequency but can be moved out of the passband using narrow filters
- this is more easily accomplished on cw than ssb due to
splatter/noise/etc commonly encountered with strong ssb signals that
bleeds into your passband.
73, Barry N1EU
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