What is a double terminated coaxial cable?

[Julia2013]

Hi All:

While reading the datasheet of EL8108,

https://www.intersil.com/content/dam/Intersil/documents/fn74/fn7417.pdf

In page 11, it says,

"
The EL8108 was designed with driving multiple coaxial

cables in mind. With 450mA of output drive and low output

impedance, driving six, 75Ω double terminated coaxial

cables to ±11V with one EL8108 is practical.

When used as a cable driver, double termination is always

recommended for reflection-free performance. "




What is a double terminated coaxial cable?
Arent' all the coaxial cables have two ends?... ...
What is the difference between a double terminated one and a common one?

 

[BigBoss]

Double terminated means there are 2 75Ohm termination resistance ( one of them is the load itself) at the beginning and end of the transmission line.

 

[betwixt]

.... one in series with the feed to the cable and one from the end to ground. As the EL8108 has almost zero output impedance, the cable sees 75 Ohms across it at each end.
This is why the video voltage from the EL8108 has to be 2V peak-to-peak instead of the normal 1V. The resistors also make a potential divider which halves the voltage across the load resistance.

Brian.