I only have female BNC, how to identify its impedance type, 50 or 75 ohm based on physical characteristic?

Question

I only have female BNC, how to identify its impedance type, 50 or 75 ohm based on physical characteristic?

Answer 1

BNC connectors have only one center pin and are not s***w on.

Wikipedia:

BNC connectors exist in 50 and 75 ohm versions. Originally all were 50 ohm and were used with cables of other impedances, the small mismatch being negligible at lower frequencies. The 75 ohm types can be recognized by the reduced or absent dielectric in the mating ends. The different versions are designed to mate with each other, although the impedance mismatch will lead to signal reflections. Typically, they are specified for use at frequencies up to 4 and 2 GHz, respectively.

NOTE. The physical sizes of the 50 and 75 ohm sockets are slightly different and can damage the "wrong" plugs."

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Answer 2

BNC 50 OHMS HAS A LOCK TYPE WHICH HAS 2 SHORT PINS.

BNC 75 OHMS IS A s***w IN TYPE,MOSTLY USE IN TV CABLE SYSTEM.

Answer 3

To identify the impedance, measure the dimensions of the BNC using a vernier. Then compare it to the manufacturer's drawing, so that you can identify the part number and hence the impedance.

Or just buy another of the correct part!