[Elecraft] K3 diversity phase drift

[David Gilbert]

I've been playing around with an application I developed to track and 
display changes in the arrival angle of incoming signals, either in 
azimuth or elevation.  I use the two receivers in my K3 (new synths) in 
diversity mod to feed the audio from each receiver into the sound card 
of my computer for processing.  It works because phase is preserved in 
the down conversion to audio.  More on the app later, but in multiple 
tests I've noticed some drift in the relative phase difference that 
can't be attributed to anything else in the system other than the K3 
itself.  A single RF source fed to both receivers through a Tee shows 
the drift, but a single audio signal fed to the sound card through a Tee 
is rock solid.

The amount of the drift varies but is roughly 3 degrees in about ten 
minutes.  It seems to be pretty steady even when the K3 has had a chance 
to warm up, with a little bit of jitter (a few hundredths of a degree or 
so) as it drifts.

I'm just curious what might be the source of the drift.  Any thoughts?

Dave  AB7E