75ohm driver?

[Ian Fritz]

Isn't RG-59 cable always 50 Ohms? If you want to drive a 75 Ohm load,
then ideally you should use 75 Ohm cable. When terminated properly (50
Ohms at the end of a 50 Ohm cable, 75 Ohms at the end of a 75 Ohm cable)
short pulses will propagate down the cable with minimal distortion and
not be reflected from the far end.

  Ian

[|[| Philip Pilgrim |]|] wrote:
> 
> Mark Amundson wrote:
> >
> > The 75 ohm is easy with standard logic. The tough part is the
> > unmentioned trace inductance and capacitance of your wiring to the load.
> 
> Ok, the load is a 75ohm resistor at the end of a 2m to 3m length or
> RG-59 cable. I guess the inductance is pretty much 0 but the capacitance
> is 60 pf/m. So it's a total 150pf cap and 75ohm resistor at 48kHz.
> 
> Philip
> 
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