[Elecraft] K3 roofing filter IMD

[Dave Hachadorian]

I was perusing the Sherwood Engineering receiver evaluation 
data, http://www.sherweng.com/table.html , and I noticed 
that the K3 2 KHz dynamic range is reported to be 
significantly better with the 200 Hz 5-pole roofing filter 
than with the 400 or 500 Hz filter.

Then I came across some IMD data on the K3 Wiki, 
http://www.zerobeat.net/mediawiki/index.php/K3_Roofing_Filters , 
which does not show much difference between those filters, 
but has an interesting footnote:
"It should be mentioned that in a published review of the 
K3, G4AON observed degradation of close-spaced IMD 
measurements with the 400 Hz, 8 pole filter: "These figures 
are for a 400 Hz bandwidth with the 8 pole 400 Hz roofing 
filter, the rather surprising discovery was the dynamic 
range improved by almost 10 dB when the 2.8 KHz 8 pole 
filter was selected." G4AON's findings haven't yet been 
independently
confirmed however."

Any thoughts on resolving these apparent inconsistencies?

Dave Hachadorian, K6LL
Yuma, AZ






















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