How am I supposed to connect two logic circuits which are not of the same family
Maybe use a common-base transistor to buffer current between the positive logic circuit and negative logic circuit, something like this:







simulate this circuit &ndash; Schematic created using CircuitLab

It's up to you to find the resistor values that give proper NECL levels at the output. You don't have to be precise, ECL is pretty robust to varying logic levels if you're not trying to get maximum speed from it.