THE HI-PER-MITE ACTIVE AUDIO CW BANDPASS FILTER IS AWESOME

I recently finished building my HI-PER-MITE cw filter.  I am very impressed at how well this filter performs  It may be one of the best active cw bandpass filters I have every used.   Here are my results from testing this awesome filter:

Here is a picture of my build

Here is a picture and audio file of an audio frequency sweep through the filter from 300 hertz to 1200 hertz

Here is what the sweep sounds like through the filter

 

Here is a good example of how well the HI-PER-MITE does at filtering a harsh square wave sidetone

 

Here are some spectrum views from AUDACITY

The original spectrum of the harsh square wave sidetone

Here is the spectrum after the HI-PER-MITE cleans up this sidetone

Even the edges of the cw waveform get cleaned up with the HI-PER-MITE


Here is the view of the end of a cw note without filtering

Here is what the cw note edge looks like after the HI-PER-MITE filtering

hipermitek1eledge

HERE IS A TEST SENDING A QRQ DIT STREAM AT 75wpm FROM FLdigi

FLdigi set to standard parameters, rise/fall time = 5ms, 3/1 dash/dot ratio, 75 wpm sending the number "5"

HERE IS A PICTURE OF FLDIGI WITHOUT FILTER [ 5 dits ]

HERE IS A PICTURE OF FLDIGI WITH HI-PER-MITE FILTER [ 5 dits ]

HERE IS A BLENDED VIEW OF THE 2 PICTURES ABOVE

HERE IS A PICTURE OF A CLOSEUP OF ONE DIT FROM FLDIGI - NO FILTER -

HERE IS A PICTURE OF CLOSE UP, OF ONE DIT - WITH - THE HI-PER-MITE FILTER

HERE IS A BLENDED VIEW OF THE 2 PICTURES ABOVE

FLDIGI 3 TONE TEST FOR HI-PER-MITE

FLdigi is sending three different cw characters at three different cw pitches; 400 hertz, 700 hertz, and 1000 hertz at equal volume. The HI-PER-MITE filter is used in the second half of the file as a narrow active bandpass filter centered at 700 hertz and does a great job of reducing (@-30db) the other two cw signals of 400 hertz and 1000 hertz. This test was setup to closely represent a typical nearby interfering signal(s) that you might hear when on the air with other cw signals that are nearby your own frequency. The HI-PER-MITE proves itself very useful to be able to successfully filter out the other signals and still be able to continue on with your own qso.

SPECTRUM of 3 tones before filter at equal volume

SPECTRUM OF 3 TONES after the HI-PER-MITE FILTER

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