The DC bias cavity contains a simple circuit board fabricated on 0.032" FR4 to provide flexible extra bias line conditioning. Wires are soldered from the 8 pin Hirose connector to three gate pads, three drain pads, and two ground pads. The redundant grounds provide one line to carry current and the other to measure voltages, if desired. Space is provided to add large shunt chip capacitors to all bias lines, and over-voltage protection diodes for the gates. Traces bring the bias to rings, which are soldered to the feed-through pins.