[wa2ise]

Stereo sound on TV channels is very similar to the way it's done on FM radio stations. There's a double sideband L-R at a supressed carrier twice the horizontal deflection frequency. There is also a pilot tone which is the same as the horizontal freq. FM radio uses 38 and 19KHz for these.

Only real difference between FM radio and TV sound is that the L-R signal has DBX noise reduction applied to it. But some early stereo TV sets didn't worry about this. It would sound something like a dolby tape played without dolby.

But one could modify an existing tube FM stereo decoder, as shown below. And it should work reasonably well.