What is the difference in TNC and RP-TNC connectors ?
RP-TNC or reverse polarityTNC connectors have opposite genders of the center contacts in comparison to standard TNC.
The male RP-TNC connector has the same external housing as a standard male TNC connector except the center male pin is replaced by a receptacle. The female RP-TNC connector has the same housing as a standard female TNC connector however the pin found on a male TNC connector is on the female RP-TNC connector.
Here is a picture example