The filter measurements I made for the 7800 were with the 7800 in the
"SHARP" setting.
Carl Moreschi N4PY
Franklinton, NC
----- Original Message -----
From: "Bill Tippett" <btippett@alum.mit.edu>
To: <tentec@contesting.com>
Sent: Sunday, May 30, 2004 12:24 PM
Subject: Re: [TenTec] Comparison of the Orion and Icom 7800
> N4PY wrote:
> >You will notice that when using SSB and using a 2400 hertz filter or any
> filter in that approximate range, the Orion filters are much sharper.
>
> Interesting data Carl. Doesn't the IC-7800 have a way to vary
> filter shape factors (like Orion's DSP tap settings)? I believe
> the 756 PRO II has this and would be surprised if the 7800 did not.
> Were your measurements with maximum DSP selectivity enabled? It
> also appears there could be a software glitch for the 1000 Hz DSP
> filter, unless there is some reason its shape factor should be so
> wide there. Ten-Tec also clearly opted for their CW filters to be
> broader at narrow settings, probably to minimize ringing.
>
> On a different but related note, I was looking over the data on
> Sherwood Engineering's website here,
>
> http://www.sherweng.com/presentation.html
>
> and noticed an important point I had previously overlooked. Using
> ONLY the 20 kHz roofing filter, Orion still has the best 2 kHz IMD
> performance of any current radio, 1 dB better than the IC-7800 using
> its 6 kHz roofing filter, and only 4 dB worse than an R-4C using a
> 600 Hz roofing filter. This is truly astounding performance, and
> attests to the fact that Orion's IF chain, even excluding the narrow
> roofing filters, is extremely robust compared to other receivers.
>
> 73, Bill W4ZV
>
>
>
>
>
>
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