Look !, no hands (aeriel actually)

[Bill Wright]

It was solid dielectric and quite small diameter. It really didn't work.

No idea but wouldn't it be for some early network thing?

Bill

[Ian Jackson]

Possibly. I believe some early ethernet used 91 ohm coax (but why 91?). But the reel we had was in 1964, so not ethernet. I wish I'd kept it. IIRC. 91 ohms is needed for getting the final impedance right when connecting certain combinations of stacked aerials. [I'm sure someone would have found it useful!]

[The Natural Philosopher]

10baseT was 50 ohm.

I think so too was the big stuff with bee stings. Yep. It was.

75 ohm is only used because that tends to match simple dipoles

Never heard of 92 ohm cable, 95 ohm is a standard but Ive never seen it or used it in a lifertime as an elkectroinics and computer engineer.

(but why 91?).

95

[Ian Jackson]

Those non-directional bee-sting taps came from the world of cable TV, and were actually used outside. Obviously, they had a tendency to leak over time. But I suppose indoors they had the advantage of being easily retro-fitted, and removed when no longer needed.

I feel a Google coming on.

OK - close, but no cigar.

[The Natural Philosopher]

It appears after further googling that 3270s and ARCNET used 90 something ohms.

[Andrew]

I can assure you that the builders coax in my house is embedded in the sand/cement basecoat plaster (1976 house) because I can see it emerging from the plaster between the gap of the final truss and the inner leaf of the gable end blockwork.

[Andrew]

That used to be the way that even professional electricians did it, in fact the wife of one of my cousins refused to have cavity wall insulation installed "because we might have to have some new power points installed".

[Andrew]

But the same comment applies. The upstairs bedroom had the skirting fixed to the blockwork with clout nails.

[Bill Wright]

An early stacked UHF array had two 50ohm yagis, two lengths of 50 ohm coax, and a simple connection to 75 ohm downlead. It worked.

Bill