STH-22SF-S1 is a Q Band harmonic mixer employing single diode and broadband circuitry to deliver low conversion loss and continuous frequency coverage for full waveguide band operations covering the frequency range of 33 to 50 GHz. The mixer extends the operation frequency of test instruments like the spectrum analyzer and frequency counter to full Q band operations. Unlike the balanced harmonic mixer, model number SFH-22SFSF-A3, the spectrum analyzer mixer does not equip separate LO and IF ports. Therefore, their LO and IF ports are combined to a common coaxial port where their LO and IF signals are shared. This feature provides a convenient connection ability when used with the spectrum analyzer or frequency counter models that have a built-in diplexer, i.e., combined LO and IF port, such as the models offered by Advantest, Anritsu, Rohde & Schwarz, some Keysight (HP or Agilent), Tektronix and Phase Matrix (EIP) models. An external diplexer can be used to connect this harmonic mixer to spectrum analyzer or frequency counter with separate LO and IF ports.