If the drive is locked with ATA security, then it won't be that simple. I don't know how this works with the HR10's and HR2x's, but on the old UltimateTV DVR's, they would use ATA security to lock the drive. If you put a used UTV drive in a computer, it would act like it wasn't even there. Basically, it's a hardware level data encryption and unless the controller passes the right key to the drive when it spins up, the drive never responds back, not even with its model number or drive parameters. The controller just assumes nothing is there.
The program I mentioned in my earlier post, MHD3, is used to unlock a drive that is using this ATA security. It won't decrypt the data, but it will send the drive an "override" unlock code that will then allow it to be reformatted, thus removing the encryption (and the data, too). It has to be run from a bootable floppy (or something emulating that). It's advisable run it with nothing but the locked drive connected to the primary controller to prevent accidental erasure of a good drive. Also, it takes a while, as in hours. I seem to remember it being something like an hour for every 30GB.
There is a way to get around ATA security without destroying the data, but I'll not go into that as it might be construed as "hacking" and that's not allowed here.