Split TV signal to make a video wall
Since you're using fairly low frequencies, this will be straightforward but tedious. What you'll need to do is to divide each channel into 3 segments - left,horizontal center and right, and bottom, vertical center and top. Then feed the 9 combinations (permutations, actually) to your 9 monitors.

You make the 6 segments using op amps. Let's say, just for reference, that your horizontal and vertical waveforms as now used have a range of +/- 1 volt. Then what you do is provide 3 offsets - -2/3, 0 and 2/3 volts. Then put each offset signal through a gain of 3. You can combine these functions, and do the whole thing in a single quad op amp, 1 op amp each for vertical and horizontal. 







simulate this circuit &ndash; Schematic created using CircuitLab

And, of course, I messed up the schematic. The op amp I'd intended is a TL084 - the TL081 is a single. Note that for loads of 10 kohm the TL084 will work out to about 100 kHz, which should be more than adequate for your needs, and you may even need to slow them down a bit by putting a small capacitor across the feedback resistors to suppress high-frequency pickup.

ETA - And another boo-boo on my part - R10 should also be 30k, rather than 10k. Damned dyslexic fingers!

For the real thing, you'll need the gains and offsets slightly bigger than shown in order to accommodate the dead zones between the TVs. Assuming 25% dead space, the offsets should be +/- 0.278, and R2 should be 12.5k. 

You'll note that there is none of the logic / screen selection which Phil Frost mentioned. The reason is simple - for this you don't need it. Signals which are out of bounds will simply be off the screen.