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Re: [CQ-Contest] Sherwood Engineering and DSP

To: <cq-contest@contesting.com>
Subject: Re: [CQ-Contest] Sherwood Engineering and DSP
From: "Rex Maner" <k7qq@netzero.net>
Date: Mon, 11 Jun 2007 00:20:13 -0000
List-post: <mailto:cq-contest@contesting.com>
The   TS 870   has the same problem and just backing off on the RF gain 
solves most of the problems  here .

Quack


----- Original Message ----- 
From: "Tree" <tree@kkn.net>
To: <cq-contest@contesting.com>
Sent: Friday, June 08, 2007 5:02 PM
Subject: Re: [CQ-Contest] Sherwood Engineering and DSP


>
> This article is a little hard to follow without the speech:
>
> http://www.sherweng.com/documents/Dayton2007w.pdf
>
> But - I think I might understand what is trying to be pointed out.
>
> If you look on page 19 at the plots of the 3 tone test - look at how
> far down the IMD products are especially the ones about half way
> across the plot.  On the R4C, they are pretty much gone at that point.
> Same on the IC781.  The IC7000 shows very poor performance.
>
> I believe this is the issue that some operators complain about when a
> radio sounds "mushy" when there is a pileup - or perhaps a lot of
> noise (noise is very similar to having a bunch of little signals in
> your passband).
>
> Often, this IMD in band perfomance is improved by backing off the RF
> gain.  I have seen my TS850 and a friends FT1000MP have an improvement
> from having the first product down about 35 db to well over 50 db using
> a two tone in-band test.
>
> And - like Rob - I am anxious to see how the K3 performance ranks.
>
> 73 Tree N6TR
> tree@kkn.net
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