Bkl electrical sma adaptorsconnectors to sma connectoradaptorscouplerssocket bkl 409039 the sma connector to tnc coupler adaptor is a standard sma sub miniature a male to tnc coupling used mainly for applications in the frequency ranges 1ghz to 18265 ghz depending upon the design the plug connector is considered as male and the socket as female depending upon the design of the inner conductor as metallic pin or as metallic pipe it has a high mechanical strength owing to the screw