RF connectors make the connection between the coax and equipment. The equipment can be either a radio or antenna. There are several type of connectors in the industry; the BNC and N will be discussed here. The left shows the BNC while the right is type N.

Most telecommunications, including LMR-amateur radio uses the 50 ohm type. There is a compatibility point to bring up to the fact the center pins between 50 and 75 ohm are a different diameter. For the N type, it's believed the 50 ohm pin is 0.0640" (1.6256 mm) while the 75 ohm is 0.0353" (.89662 mm). One issue is a larger pin inserted into a smaller hole (receptacle) will damage the latter. On the other hand the small pin can be inserted in a larger receptacle at the expense of intermittent or no contact, causing a bad operation.

The other issue is pin depth for either type connector. If it's too shallow (inward) will also produce intermittent or no contact with the mating receptacle connector. If it's too far out will damage the mating connector.

For example, the Cablewave Systems FLC 12-50 NM was evaluated here. It's a end connector for LDF-4 (50) type of copper jacked RF cable (50 ohms). The part number is 738802 which most likely is obsolete and no longer available (NLA) on the new market. However you may find some New Old Stock (NOS) on line. The distinctive feature is the cable's center conductor does not require soldering. Instead it is pushed into a "female" part, inside the main body housing. Shown here is the components out of the package. Obviously the two items on the left are from the cable to be used. The Author confirmed the center conductor fit the "female" part plus this illustrates the flair of the outer conductor when it's put together.

Here's a nice list of all kinds of connectors produced by produced by RF industries which will give you and idea what's out on the market. Check with your distributor on how to purchase items like these.