[Elecraft] K2 Improved Sidetone

[David Pratt]

While I had my K2 #01583 control board out to increase the value of C42 
from 10nF to 100nF as per Builder Alert #19, I decided to carry out the 
sidetone mod suggested by Marteinn Sverrisson TF3MA.  I had already 
carried out the previously suggested sidetone mod by adding a 47mH choke 
across RP5 pins 7 and 10 and this mod did improve the sound of the K2 
sidetone.

The TF3MA mod involves cutting a PCB track and using the same 47mH choke 
in a low pass filter configuration.  I reluctantly cut the track in the 
recommended place, repositioned the choke and fitted a 2.2uF capacitor. 
And, am I pleased that I did the mod?  Yes I am!  I am now getting a 
near sinewave sidetone which is very pleasing to the ear.

Thank you TF3MA, your sidetone mod is highly recommended.

David G4DMP