[Drake] R4c audio modification

[Wa1cvn at aol.com]

Hi Guy,
I have installed both the power supply mod and the Audio mod in two of my  
R-4c's in the same serial number range and can say that there is a big  
improvement in the Audio.  The high frequency back ground noise is  gone as well as 
the long term listening fatigue.  Of all the mods out  there, these two are the 
most beneficial.  The audio resembles that of a  R-4B in quality.  Also, the 
PTO is more stable because the heat from the  Audio output transistor has been 
removed from behind the PTO area.  This  reduced the warm up drift from almost 
a 1 KHz to 200 Hz or less depending on  ambient temperature.
73
Dave
Wa1cvn