The classic Ethernet according to 10Base-5 was built with the "Yellow Cable" of the type RG-8A/U, also called Thick Ethernet. This coaxial cable consists of the inner conductor, the dielectric, the shielding and the cable sheath.
The inner conductor( copper, silver) has a diameter of 2.17 mm, the dielectric with the shield or shields (braid, closed sheath) ranges in diameter from 6.15 to 8.28 mm, and the fire-retardant outer sheath made of Teflon or polyvinyl chloride( PVC) ranges from 9.525 to 10.287 mm. The yellow coaxial cable is extremely bulky and, because of its thickness, has a relatively large bending radius of 25 cm and markings for the TAP connection at 2.5 m intervals. The impedance is 50 ± 2 ohms, and the signal propagation delay should be at least 0.77c.
Due to the bulkiness of the Yellow Cable, the small bending radius and the interference-prone connection of the transceiver with vampire clamps, the original version was only used until the end of the 1980s and was replaced by more flexible cable solutions.