Fw: [TenTec] Receivability
Gary Hoffman" <email@example.com
Tue, 29 Oct 2002 18:22:59 -0500
> I think it is important to note that a big difference is made by where
> in the receiver chain the filters are located.
> In the Pegasus, as you know, the DSP work is done at the end of the chain.
> On the Corsair, and many other radios, the crystal filters are in the
> stages of the chain.
> Since they eliminate much noise up front, before it gets fully amplified
> the following stages, they can be much more effective than the same
> filter applied downstream. In fact, since they can help prevent
> overload, they can be dramatically helpfull.
> I don't mean to suggest that the IF DSP filter in the Pegasus is a poor
> filter. I only note that it is at the end of the chain, and less
> of that fact.
> 73 de Gary, AA2IZ
> ----- Original Message -----
> From: "George, W5YR" <firstname.lastname@example.org>
> To: "Gary Hoffman" <email@example.com>
> Cc: "Mike Hyder -N4NT-" <N4NT@charter.net>; "Scanandoah, Alan"
> <firstname.lastname@example.org>; "Ten-Tec Reflector" <email@example.com>
> Sent: Monday, October 28, 2002 11:19 PM
> Subject: Re: [TenTec] Receivability
> > Very interesting, Gary, and thanks!
> > I have made detailed spectral comparisons between the IF DSP filters in
> > ICom 756 PRO, the Kachina 505DSP of similar architecture and the Icom
> > with conventional crystal filters. There is no comparison whatever
> > the shape factors and overall shapes of the PRO filters compared to any
> > the others. The PRO filters are mathemeticallu nigh perfect in shape and
> > performance. I think that you have found that the Pegasus IF DSP filters
> > are not the equal to the conventional INRAD filters - that is very
> > surprising to me.
> > Thanks again.
> > 73/72, George
> > Amateur Radio W5YR - the Yellow Rose of Texas
> > In the 57th year and it just keeps getting better!
> > Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
> > K2 #489 Icom IC-765 #2349 Icom IC-756 PRO #2121
> > Gary Hoffman wrote:
> > >
> > > George,
> > >
> > > I have cascaded 10 pole Inrad filters in the Corsair. The skirts are
> > > deeper and sharper, which is the thing that helps the most.
> > >
> > > The low frequency, "IF" DSP filters in the Pegasus work well, but they
> > > don't work nearly as well as the Corsair. You could really see the
> > > difference in the contest.
> > >
> > > 73 de Gary, AA2IZ
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