Source Information

A complete list of supported video capture devices is here.
This old page contains a few known working SageTV capture devices.
Device 	Broadcast/Input Type 	SageTV Interface Type	Link
Hauppauge HD-PVR 	Composite; Component 	Built-in support 	
Hauppauge HD-PVR2 	Composite; Component Video; HDMI	Built-in support 	
Hauppauge Colossus 	Composite; Component Video; HDMI	Built-in support 	
SiliconDust HDHomeRun 	ATSC; QAM 	Built-in support 	
SiliconDust HDHomeRun Prime	QAM; CableCard 	Network Encoder