[Elecraft] 250 Hz and 400 Hz Filter Measurements

[Jim Brown]

On Sat, 17 Jul 2010 10:48:36 -0700, John, KI6Wx wrote:

>My advice would be to
>disregard this report because the measurements were not made in such a way
>as to accurately determine the response of the K3 filters

John,

You are badly mistaken. The K3 was excited by broadband noise, and there was 
enough of it for none of the noise to be internally generated. I am the 
author of the study, and if you had read the email that pointed to it you 
would have seen that. 

These measurements are QUITE valid, and represent the response of the radio 
from antenna input to audio output. The wide and narrow measurements on the 
same page are the same data, plotted to different scale -- the narrow plots 
to show filter bandwidth, the wide plots to show behavior well down the 
slope of the filter curve. The dynamic range of the measurement is at least 
75dB. 

73, Jim Brown K9YC