[Test-Equipment] question

[Steve]

At 12:11 PM 12/12/2009, you wrote:
>The K-H filters are certainly usable in the audio. They can be make a good
>sound system sound like a telephone in bandpass mode and a bunch of other
>things. They could likely filter out an annoying tone as a notch filter. I
>don't remember how good the noise floor is, but it's likely pretty good.
>
>In the lab, they are useful for cleaning up signals. Most are high
>pass/low pass/band pass/band reject.(Not all at the same time)
>
>Note, My comments refer to engineering based audio, NOT audiophoolery.

I used to have one of these years ago and was very disappointed to 
find the skirts were nowhere near sharp enough for use as a 
narrowband CW filter. They work, but mine just wasn't worth the 
effort. The stock Heathkit crystal CW filter was much sharper.

Steve K0XP