A transmit-receive switch has a transmit port, an antenna port, and a receive port. A licensing authority provides keying information to a multitude of manufactures that insert the keying information into trusted devices. A private key of a private key and public key pair is stored in the secure digital appliance in such a way that the stored private key cannot be obtained by tampering with the secure digital appliance. The axial support may have a first diameter and a second diameter larger than the first diameter.