[Elecraft] sidetone sinewave mod -- applicable to K1 also?

[Wallace, Andy]

I was wondering if the sidetone mod for the K2

(http://www.qsl.net/ve3mcf/elecraft_reflect/K2_Sinewave_Sidetone.txt)

would be applicable in part to the K1. I normally run my K1
through the speaker, but this past weekend I used headphones.
The sidetone did not sound as smooth as I would like -- though
setting STL to 2 made it tolerable.

Part of the K2 sidetone mod is to put a 47 mH inductor across pins
7 and 10 of RP5. This bridges the two 470 Ohm resistors with the 
inductor. All of this winds up on the BYPASS pin of the LM380N-8
audio amp. 

Looking at the 30 year old (!) PDF app notes on National's site,

http://www.national.com/pf/LM/LM380.html

...I am still trying to figure out all the particulars of how to
properly use a 380. 

(Interesting that they note to avoid 5 to 10 MHz oscillations
under high current loads you need a resistor and cap in series
to ground on the output pin. Elecraft has these but uses different
values than what's in National's PDF.)

I do not know what the bypass pin does -- National does not explain it.

Anyway -- the K1 appears to have a very different sidetone circuit, but
I am wondering if the tone could be smoothed by adapting the K2 inductor
scheme into the bypass area of the K1 LM380 -- maybe by putting 
a 47 mH inductor in parallel with a 1K resistor, and lifting the ground
side of C33? But the K2 gets its sidetone IN the bypass line, so I
am totally confused...........

Hopefully someone who knows the K2 and LM380s can pick up the thread.
Bottom line is, the K1 sidetone is probably not nice and sinusoidal either!

-Andy