Re: Latest Sherwood table

Posted by wayne burdick on Dec 31, 2010; 10:48pm
URL: http://elecraft.85.s1.nabble.com/Re-Latest-Sherwood-table-tp5882563p5883087.html

Both the Inrad and Elecraft filters use crystals that are hand-
screened for low IMD. We built several high-performance test fixtures  
for ourselves and Inrad to make sure this was done consistently.

A slight improvement may be possible, but it would probably double the  
cost of the filters. The K3's receive IMD numbers are already excellent.

73,
Wayne
N6KR

On Dec 31, 2010, at 2:00 PM, juergen wrote:

> Hi Bill
>
> I understand the differences in IF frequencies.
>
> The question still remains, how much extra  IMD dynamic could be  
> squeezed from the K3 if high performance 8mhz roofing filters were  
> used. We have seen no data on the K3 filters that quantified their  
> impact on IMD dynamic range.
>
> PA3AKE has shown that careful selection of crystals and building a  
> roofing with due care contributes a significant amount to the  
> ultimate IMD dynamic range.
>
> http://www.xs4all.nl/~martein/pa3ake/hmode/roofer_intro.html
>
> I wonder if a company like Network Sciences did build an improved 8  
> mhz filter  how much performance  increase we would see. Surely if a  
> 20db jump in IMD dynamic range can be achieved at 70mhz, imagine  
> what the improvement would be at 8mhz! We will never know unless  
> someone tries.
>
> 73
> John
>
>
> --- On Fri, 12/31/10, Bil Tippett <[hidden email]> wrote:
>
>> From: Bil Tippett <[hidden email]>
>> Subject: Re: [Elecraft] Latest Sherwood table
>> To: [hidden email]
>> Date: Friday, December 31, 2010, 4:18 AM
>>> I wonder how such a high
>> performance filter would work in the K3?
>> Not that its
>> needed in the K3. However in the interest of science,
>> it might be a worthy
>> pursuit. It also might push the K3 well ahead of the FT5000
>> in ultimate
>> performance.
>>
>> Not very well since it's at 70 MHz.  ;-)  The
>> Inrad filters are
>> already better than whatever is in the FT5000 since
>> Sherwood measured
>> ultimate rejection in the K3 at 105 dB vs 90 dB for the
>> 5000.
>>
>> 73,  Bill  W4ZV
>>
>>
>>
>>
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>
>
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