[Elecraft] K2: TF3MA's Audio Mod

[Mike Fitzgibbon]

Great mod Matti!  Always thought the K2's audio sounded a little 
tight...  tacked a couple of .1 uf caps across the pads per your 
instructions and it sounds noticeably "better".

It is an easy mod and I heartily encourage others to try it...easy to 
do...and remove... if you don't think so...but I bet you leave it....

Thanks Matti...you da OM!

Mike Fitz  N0MF


TF3MA wrote:

But I discovered that my K2, had a rather limited low freq audio
response. So I took a look at the schematic for the audio circuit in the
K2...

The original low freq. cutoff (-3db) freq. is approx. 640Hz (with KAF or
DSP moduls installed) or 400Hz (with no audio moduls) determined by C25,
C26 and the 5kOhm volume control (and NE612 mixer impedance), to extend
the audio frequency response for the low freq. I put
0.1uF SMD across C25 and C26, extending the low frequency response to
approx. 320Hz. This improves the SSB sound of the receiver, and improves
SNR when copying low pitch CW signals. This simple mod increases the rx
audio signal at 300 Hz by about 3dB.