On Fri, 25 Jul 2008 11:24:47 +0100, G3SVL wrote:
>It's not just the filter that matters, its the filter skirt response
>too.
YES! As it happens, I recently completed a somewhat extensive series of
measurements of filters in both my K3 and two FT1000MPs. Most are Inrad
filters. They can be downloaded as a pdf with the following link. The
measurement technique uses band noise as a source and does an FFT of the
audio output. As a result, it shows the cascaded (total) response of the
IF filters and the audio filters (as well as distortion in the audio
system, if there is any). The FFT is a high quality pro audio analysis
system that runs on my PC.
http://audiosystemsgroup.com/FilterTestNotes.pdf
I did not measure the 125 Hz or 63 Hz audio filters in the MP. Only so
many hours in the day. :)
73,
Jim Brown K9YC
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