[Elecraft] My K3's hissy and noisy audio

[Paul Christensen]

> On the other hand, plug a Heil ProSet with its 200 Ohm elements
> into an unmodified K3 and the -3dB point is 80 Hz ... low enough
> for communications use without being overly sensitive to hum and
> other low frequency noise...

That would be a good choice for the stock K3.   One thing to note is that 
most coil-based headphones and speaker elements do not have a flat impedance 
curve as a function of frequency.  Some can vary considerably from their 
rated impedance rating.  The Z at 50 Hz can be vastly different than at 5 
kHz.

Also, moving the C9 & C13 headphone coupling capacitors up in value will 
allow for grabbing most any headphones.without worry as to how response will 
be affected.  I used an old set of Koss Pro4/AA for testing but use 
Sennheiser PCX300 or Bose Triports headphones when operating my K3.

Paul, W9AC