[Elecraft] K3/K3S receiver and high-precision frequency determination?

[Frank O'Donnell]

Sometime (probably last year) I remember seeing a discussion of why the 
K3/K3S receiver isn't suitable to do high-precision frequency 
measurement tests at the level of hundredths of a Hertz. As I vaguely 
recall, the receiver is designed so that its frequency actually varies a 
bit intentionally, and I remember someone posting a plot demonstrating 
this. However, I'm striking out on finding any of those posts. Can 
anyone either help with them, or point to any other 
discussion/explanation on this?

Thanks much,

Frank K6FOD