On 2018-Jan-23, at 12:27 PM, Paul Koning via cctalk wrote: > The Ethernet spec says that the cable OD is in the range .365 to .415 inch, > which is 9.27 to 10.54 mm. The nominal OD of RG-8/U is .405 inches, or 10.28 > mm, which is within spec for Ethernet cable. > > One place where the two cable specs differ is in the velocity factor, 0.66 > for RG-8/U and 0.77 for Ethernet cable. That relates to the dielectric -- > solid polyethylene for RG-8/U and foamed material (unspecified) for Ethernet. > Also, Ethernet requires a solid inner conductor (for the tap) while RG-8/U > may come stranded. (Maybe only in some variants, I'm not sure.) And there > are the stripes, of course, but those have no electrical significance. You > can use a tape measure if you don't have the stripes.
I was attempting some calculations to see if I could derive the 2.5M transceiver spacing and was wondering what the velocity factor for the cable was, as it should affect the transceiver spacing in theory. I haven't seen any pictures during this thread of the transceivers we used with the 10MB yellow hose - heavy gauge metal boxes about 3" * 4" * 1" with N connectors. I remember piling up the 3 ft diameter loops of yellow coax in the machine room where you had a bunch of machines together and didn't need the cable lengths between them, until the DEC DELNI (ethernet AUI hub) cleaned up that mess.
