The TC-01 has a lot of board space and analogue circuitry to drive the RF modulator.

I want to bypass as much of this as possible.

The TMS9929 outputs Y, R-Y, and B-Y (component) signals which require a PAL encoder for composite video.

I use a SCART to HDMI upscaler box. These are mass produced for people use their old SDTV gadgets (e.g. DVD players) with modern HDTV screens. This avoids the effort of adding this ability to every retro-computer I have.

My upscaler accepts composite video, RGB and component video. So I thought I would simply need three 75-ohm RF buffers to output component video.

Apparently if you do this, the colours are a bit off, because the colour burst is in the black reference level period of the baseband video signal. See: https://hackaday.io/project/13056-tms9929a-rgb-and-component-adapter
which is a board to solve this issue.

There is a very compact board that produces RGB output and fits underneath the TMS9929. About £37 including postage and VAT.

You can even buy an FPGA replacement, the F18, but at around £65 this is half the cost of a populated board.

I want to keep the total cost less than the cost of buying a populated board.