[Elecraft] Mystified with KPA 100 4 MHz audible tone

[gehringc at charter.net]

The KPA 100 manual points out during the receiver test  
"The signal from the KPA100's 4-MHz crystal oscillator (X2)
may be audible at the high end of the 80-meter band. If this is the case,
you can move it to a point just above 4 MHz using trimmer C27. The
signal from the 4-MHz oscillator on the K2 Control board may be
much stronger. Rotate C27 slightly to identify the KPA100 signal."
Well I verified that I can in fact hear the two identical and separate tones by adjusting the trimmer C27 in the KPA 100.  I am just not sure what the intent of the adjustment is other than to verify the two sources for the audio tone on 80 meters.  What am I doing when I adjust C27 to move to tone above the 4 MHz region?

73 KI4DGH
Chuck G.