My question relates specifically to OTA HDTV.  In 2004, I was able to buy an LG tuner/DVR, a device which received ATSC and NTSC -- both types of TV -- and worked as the tuner for a Dell HD TV LCD.  It has a hard drive which allows recording HDTV (hence, I call it a DVR.)  Subsequently, I bought a Sony HD HDD500 tuner/DVR which is much larger and does the same recording.

Both of these units work off of an old TV antenna in the attic and receive HD TV, regular TV and DTV from about 35 miles away.

Neither of these units are currently being sold and I cannot find anything other than TIVO, DirecTV, those kinds of pay TV systems DVRs.

Finally, my question:  Why are only the pay TV types of DVRs available.  LG and Sony do not answer my questions.

Thanks for your help in advance.