Reel to reel video: how to direct signal to TV

[Redeyegravy]

New to this forum! I have noticed that some of you have worked with reel-to-reel video formats. I have purchased five machines and have had no luck with any of them. Each of them is missing the RF adapter box that presumably makes this easy.

I have tried five different tapes on 3 SONY AV-3600s, 1 SONY AV-3650 and 1 PANASONIC NV-3110.

I have used the PL-259 video out and connected it to the "cable-in" on a CRT television. Have tried the whole gamut of channels. I have adapted the PL-259 cable to an RCA and plugged into the "Video in" on the back of the set. No results.

I have cleaned the video heads and baked tapes but have not even had the slightest hint of a picture.

Is there something I am missing here. Something head-slappingly stupid I am overlooking? I find it hard to think that all five units are going to produce no signal--but maybe that's what happens to them after 50 years.

Any guidance appreciated.