[Elecraft] sidetone mod now works

[kt5x at cybermesa.com]

The sidetone mod by TF3MA was installed in my K2 right after Marti posted 
it.  I obtained a 47 mh inductor for this mod from Elecraft.  The mod 
resulted in an improved sidetone, but left room for further improvement, 
especially at lower tones.  Additionally there was an objectionable pin-prick 
sound at the make of the muting that was annoying to hear.

Recently I decided to revisit this situation.

I noticed in Marti's write-up that HIS 47 mh inductor had an internal 
resistance of 180 ohms.  With the K2 apart, I measured the inductor I had 
received from Elecraft and sure enough, it had an internal resistance of only 
40 ohms.  This would entirely change the frequency response Marti's peaking 
high-pass filter.  Elecraft is apparently using an 82 mh inductor in its mod, 
I obtained that, and found it has an internal resistance of 60 ohms which 
would seem to offer less than an ideal result.

I put a 150 ohm resistor in series with the 47 mh / 40 ohm inductor 
originally used when I modified the radio some years ago.  Folks, the 
difference is DRAMATIC !!!  The sidetone is louder, clear, and is that way 
across its entire range from 400 to 800 cycles.  Not only that, the tone is 
so much stronger that the slight pin-prick click from the make of the muting 
line is all but completely inaudible in the strength of the sidetone and no 
longer objectionable.

A big thank you to Marti and to W3FPR who both stayed with me through my 
frustration trying to make this thing right.  For a while they must have 
thought my hearing was the main problem because the radio seemed to have the 
right modifications in it to sound well.  

Maybe this will be helpful information for others.

73,  Fred KT5X