Had a diplexer between my HR20-700 and the Sat to run a tv in the next room. Couldn't understand why I was losing some recordings on HD locals. When the installer came to hook up ny new HR22 that replaced my old HR10. I pointed out that I was getting no signal on on tuner on sats 99C and 103C. They won't go thru the diplexer. Every day I learn something new.