[Elecraft] Need comparison values on sidetone mod

[Lenny Wintfeld]

Hi

I tried the sidetone mod over a year ago using the 47k resistor and a 
20mh choke I had laying around. The result was disappointing. I didn't 
make any measurements back then, but with a "listening test", I came to 
the conclusion that the mod was ineffective and backed it out.

I just did the mod again. This time with a 47k resistor and a 68 mh 
choke. I was a little more scientific this time. I used spectrogram for 
before and after measurements. The results are as follows

a) Before the mod: 2nd harmonic -23 db, 3rd harmonic -21 db both wrt 
680h Hz tone
b) After the mod:   2nd harmonic -32 db, 3rd harmonic -27 db both wrt 
680h Hz tone
c) The all important "listening test": sounds a LOT cleaner.


Has anyone else done spectrogram before and after measurements? I'd be 
curious to know if my numbers are in the same ballpark as others'.

73,
Lenny W2BVH
K2  sn 1520