More on my adventure
Thanks to everyone who has responded.
On closer inspection of my 811, there are no analog pins on the unit's connector, it has a DVI-D connecter which I have learned means digital signals only. This rules out any low cost/simple adaptors. (S)VGA is normally analog only and the cheap adaptors simply route the analog pins available on DVI-A and DVI-I connectors to the appropriate pins on the (S)VGA connector.
There are some product on the market that can convert the pure digital from the DVI-D connector to an analog signal on a (S)VGA connector. These run around $300 or more. The problem is it is still an analog signal going into the supposedly HDTV.
I've learned that this TV was designed in 1999 and at that time there was no DVI connector technology available. The owner's manual shows the companion external HDTV converter connecting to the TV at this "special" (S)VGA connector. The question is can this "special" connector receive real, digital, HDTV signals?
A person at a local RCA service center said he would check in to it. If I don't hear from him in a couple of days I'll try to get a schematic from them and see if I can figure what is going on myself.
RCA claims this is a 1080i compatible unit, surely there are others that own this set who want answers like me.