An HDTV receiver box to insert in vintage TV IF strip?

[ChrisW6ATV]

Here is a Rube Goldberg scheme that could allow a person to change channels on their antique TV set and receive the corresponding digital signal.

Items needed:
-DTV set-top box with remote control
-Universal remote control with multiple "macro-programmable" keys
-Agile VHF NTSC modulator, modified to allow external access to channel selection (usually DIP switches)
-12 DPDT relays, miscellaneous diodes, low voltage power supply, etc.

The idea is, you modify your TV's tuner to bring out one wire per VHF channel position and a common ground wire. This could be done by some kind of optical or magnetic-sensor assembly that detected what channel was selected, or maybe even using contacts already on the tuner's wafer switches. The twelve wires go to the relays, turning on whichever one matches the channel selected. One contact on each relay is wired to one macro button on the remote control that is pre-programmed to send the command to choose the desired channel on the DTV tuner. (A timer circuit may be needed to make the "button press" a momentary event.) The other relay contact turns on a diode matrix wired to the DIP switch contacts of the agile modulator, changing its output to match the old NTSC channel number of the DTV tuner's selected channel. Connect the DTV tuner to the modulator and the modulator to the TV's antenna inputs with a matching transformer. You now have an on-the-fly digital-to-NTSC converter.