Have you seen old LAN cards that have a coax connector. Well, they have all the cable driver electronix in one IC. You can see the datasheet of that IC and use it to make your driver.
Keep in mind that you have to have some kind of modulation to drive the coax.
Only true amplifier with 50 output impedance will give you well defined driver. A switch like output of TTL chip will give you defined output impedance only at levels 0 and 1. At both transitions output impedance is much higher.
Have a look at the SN54S140 from Texas Instruments: https://focus.ti.com/lit/ds/symlink/sn54s140.pdf
It is dual 50Ω driver. If you can't get it you can use its equivalent schematic to construct a 50Ω driver ..
Regards,
IanP
u must use standard line driver/recievers or...
for TX: parallel several TTL buffergate, input your signal, divide its output by a resisor voltage divider (the output impedance of the divider should be 50 OHM), and drive the line
for RX: use a fast schmitt trigger (100mv is sufficient) and a ref. voltage=1/2 driver's output voltage AND a 50 OHM resistor in front of the Schmitt trigger to impedance matching.
i use an opa to driver the line ,the output have a 50om resistor to match the 50om line load ,the input ttl signal is 5v peak value.if the output signal should be 5v peak,then should the amplifier be *2 ?