On 5/23/22 21:34, Sentrytv via vcf-midatlantic wrote:

I am 99% sure that the ZX 81 or the TS 1000 has a standard RF modulator.

It does; one of the little Astec canned modulators. At issue here, though, presumably, is the NTSC-format baseband video being fed into that modulator. -Dave -- Dave McGuire, AK4HZ New Kensington, PA