[Elecraft] K3 receiver desensing on CW during contest

[d.cutter at ntlworld.com]

Let's see: 122 to 140dB:  only 15% increase! a walk in the park...  
 ; - )

David
G3UNA


---- Geoffrey Mackenzie-Kennedy <gm4esd at btinternet.com> wrote: 
> Larry N8LP wrote on 24 Februay 2009, at 02:40.
>  
> > I think the days of receivers with xtal filters are numbered. High speed
> > ADCs capable of 140dB dynamic range without xtal filtering are on the
> > horizon. A 20-bit ADC with enough processing gain would do it.
>  
>  ------------------------------ 
> Larry,
>  
> You could be right, given an adequate amount of R&D funding and time.
>  
> When the performance of a state of the art HF receiver using xtal filters
> will be surpassed by one digitizing at signal frequency is an open question
> I think.. The performance standard in terms of Spurious Free 3rd
> Order dynamic range vs. time set in recent years by real HF superhet
> receivers using xtal filters, as I know it to be, is:
>  
> Year     3rd Order SFDR    3rd Order SFDR    Filter     Noise
>                 @ 2 kHz                In Passband         BW      Figure 
>  
> 1993          110 db                      95 db           400 Hz     8 db 
> 
>  2007       122 db approx            115 db           500 Hz     7 db
>  
>  
> So don't put the old horse out to pasture just yet :-)
> 
> Sorry to have digressed from the subject matter.
>  
> 73,
> Geoff
> GM4ESD
> 
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