knwalter,
Some newer RCA TVs use the RCA IR protocol, device 15, but with a wrinkle. Ordinary RCA protocol uses a modulation frequency of 58KHz. The newer TVs use 38KHz. For example the RCA L32HD41 (remote RC246) uses 38KHz. This number seems to be quite close to that of your TV.
I doubt very much that RC64 has the ability to send this signal. However, if you put the remote right in front of the TV, so the signal is really strong, it might work using 10047. If so, I think that would confirm the 38KHz operation. But the frequency is very different, and it might not work no matter how strong the signal.