The STO-0509300-T-E1 from ERAVANT is a Vector Network Analyzer Extender with Extended Frequency 150 to 220 GHz, Input Frequency 6.25 to 9.17 GHz, LO Frequency 6.25 to 9.17 GHz, Output Power -5 dBm (Test Port), Input Power -3 to 3 dBm (LO, RF). More details for STO-0509300-T-E1 can be seen below.
