Strangely enough if you set the 1.5Khz filter to engage at a 2Khz DSP
bandwidth you actually see the width change as you adjust from 2Khz
down to 1.5Khz... I'm not sure why you can't set things this way to
get the DSP filter out of the way and allow one to see only the shape
of the IF filter. Perhaps the only way to pull this off is to use the
AFV functions...
Anyway I set things back the way I have my radio at all times and set
the 1.5Khz filter to engage at 1.60Khz. I took a sample of the AF
output with an Elecraft N-GEN noise source connected to the K3 antenna
input.
I used a spectral tool with averaging enabled and allowed the
application to average 4000 samples. The 6Khz spur shown (as well as
others) have been proven to be artifacts produced by the sound card
used. Sample rate used was 16Khz.
Image can be seen here:
http://dl.dropbox.com/u/1493706/K3/1.5Khz%20Filter%20Noise%20Source.png
If anyone has any ideas on what else to try in order to capture the
shape of JUST the IF filter please let me know and I'll retake the
measurements.
~Brett (KC7OTG)
On Fri, Jan 29, 2010 at 3:57 AM, Barry N1EU barry.n...@gmail.com wrote:
I have a request for anyone out there using the Inrad 1.5Khz narrow ssb
filter and who can make a simple .wav recording. Please set width to 1.5Khz
and tune to an empty part of the band and make a 10 second recording of just
band noise with RX EQ flat, and email me the .wav file.
I'll make a high quality passband plot and post for all to see.
Thanks 73,
Barry N1EU
--
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Sent from the Elecraft mailing list archive at Nabble.com.
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