[Elecraft] KDSP2 & Strange CW sound in my headphones.

[Jeff Burns]

I just got my KDSP2 installed. It seems to work well, but I have noticed a
surprising interaction with one of my pairs of headphones.

With the offending headphones and noise reduction on, a CW signal sounds
choppy. The note is more of a square wave than a nice sinusoidal note.  If I
turn off noise suppression the CW note sounds normal. I do not hear this
problem with any of my other headphones.

The offending headphones are a bit strange. They are made form a set of
David Clark model hearing protectors. The box has a computer generated label
that says "MON 27". The cord plugs into a mono 1/8 in jack on one of the ear
cups. I called David Clark to get a replacement cord for these and was told
they did not make them. Inside the ear-cups are earphone elements with this
labeling "Earphone H-143/AIC Electro-voice". The DC resistance through these
earphones is only 10 Ohm.  These phones always have low audio, but they have
worked well for me.

Any idea who made these headphones? Why do they make CW signals sound bad
when the noise reduction is turned on?

Jeff Burns
AD9T