When we switched to ATSC in the United States I realized, "Hey, there is no VHF low in most areas. Certainly not here." So I put a two port splitter backwards (combiner) on my antenna feed and hooked up a cable box to the other side on NTSC channel 4. We once had a channel 3 and old habits die hard! So now on my Magnavox recorders I get all the OTA channels and a virtual OTA which is actually cable. I have two shows I record on AMC weekly that we may not be present/coherent enough to watch, so it works out perfectly. The one thing that could be a problem is that cable bleeds back into the antenna system. I use a preamp on my antenna and don't believe it is being radiated back to the neighbors. Has anybody else tried this?
I was told early on by people that should know, that this would not work, or at best would work very poorly with crosstalk and multi channel harmonic interference. That's why they make video mixing amplifiers (I was told). I never tried it because of this advice. I am glad it's working for you, and another assumption bites the dust. I LOVE it when that happens.
Evil is charming and beautiful. It makes you doubt yourself. It asks for one small compromise after another until it whittles you down, and it functions best when no one believes in it.-JOA
I don't want to cause problems for Comcast and just assume that their cable boxes and digital adapters wouldn't bleed OTA back into cable, and my antenna preamp would block any interference. Now you could hook things up completely wrong and broadcast cable to your neighbors if you didn't know.
Yes, I have done essentially the same thing you are doing without issue. In my case, I was feeding OTA plus the RF out from my sat box on channel 3, combined with a backward splitter on the same coax. So I had all my OTA channels plus everything on sat on channel 3.
I have since abandoned that and come up with a much better solution, but it involves a PC.