Adding to Half-Saint's comments above:
The only dedicated 2600 I've owned (I'm not counting the 7800 currently in storage) was an Irish-market, Irish-manufacture 2600jr. It was used in Ireland on a PAL television, and only had RF output - no SCART, S-Video, or composite. As far as I'm aware, this was the standard model for PAL markets.
I believe (though I could be mistaken) that there were SECAM 2600jr models made with SCART output. However, my understanding is that those models were specific to the French market, where SECAM was the TV standard and SCART connections were required for A/V devices designed to connect to a television. SECAM and PAL are not directly-compatible, though they are close in spec - a SECAM signal will generally display on a PAL TV, though likely with no colour and distorted sound.
As this relates to the original conversation: coax (as mentioned previously) is still used in Europe for free-to-air television. The European antenna connector (aka the 'Type F', IIRC) connector is a push-on, not screw-on, device as it is in the US. It is not the same form factor as an RCA connector, and it's difficult to confuse (or mistakenly connect) the two.
Having said that: Half-Saint, I suspect that your 2600 is having a hardware issue. If your TV is still capable of tuning free-to-air broadcasts, it should be able to tune into the 2600's signal. My guess is that the RF modulator is shot, but first check that the TV can handle analogue RF signals; some newer ones may not be able to. Given that it looks to be in sync with the 2600, I'm guessing that it can - but Internet diagnoses can sometimes be wrong, especially now that I live in NTSC-land