[hpsdr] RX1 to left RX2 to right - coherent ?

[Erik van Maanen]

Yes VAC 1 is normally for RX1 and VAC 2 for RX2.
Make both VAC 1 and VAC 2 point to the same audio device and set both to 
stereo
Use the pan function on the VAC to set VAC 1 on the left channel and VAC 
2 to the right channel.
Be careful there are three pan controls you need the top one in the 
cluster of two and the separate one next to the VFOB Band controls.
Don't know the logic behind this but it works.

I don't know if your goal is just to listen or to do also measurements, 
in that case some advice.
Be careful with external VAC, the ones we tested are far from coherent, 
direct IQ to disk streaming is better using the WAV record function.
I cannot find any info in the AFE8220 datasheet about coherence of the 
two channels. they are probably only frequency synchronised.
Angelia and Orion for example are phase coherent and stable <1 degree 
over 12 hours, the minor drift is probably from an analog component and
not the design itself.

Hope this answers the question.

73, Erik PA3DES