General purpose harmonic mixers that operate with both even and odd harmonics have one diode, and require a DC
                return path for the diode current. This DC return path follows the IF path in the diplexer, and the device attached to
                the IF port of the diplexer must have some provision for the diode current. This may take the form of the 50 ohm (DC)
                input impedance of the IF amplifier, an inductor to ground or a diode bias circuit. Mixer conversion loss is dependent
                upon frequency, harmonic number and applied LO power as well as diode current. Many spectrum analyzers have a
                mixer bias provision, and this bias can be used to peak the output from the mixer to optimize performance.

                Mixers designed to operate on even LO harmonics only or odd  LO harmonics only have two diodes in an anti-parallel
                configuration and do not require bias for normal operation. Bias can be used, however, to make an "even only" mixer
                operate with odd LO harmonics or an "odd only" mixer operate with even LO harmonics.

                In order to apply bias to the harmonic mixer there should be no DC path to ground through the IF amplifier. If necessary,
                place a blocking capacitor C in the IF amplifier input line. The capacitor should be large enough to pass the lowest desired
                IF frequency. Keep the resistor lead length (X) to a minimum. An alternate circuit is also shown for providing the DC return
                path to ground without an external bias voltage source.

                Shown below is a simple circuit for supplying bias to your mixer.