[Elecraft] Older Serial# K3

[David and Dianne on Comcast]

"....There have been several changes to the K3 and not all of them published. The early PA and driver were 
replaced around Jan 2008..."

Dave, 

Can you please elaborate on unpublished changes especially those with the PA section?  

I am an owner of an early serial number K3 and have been trying to get info on this for a while.

Thanks an d 73 de N1LQ-Dave