HPM test facility is commissioned in LAMBDA. The HPM source is axial vircator, which is driven by indigenously developed 7-stage bi-polar Marx generator. The integrated assembly of Marx is capable of generating 350kV, >10kA and 300 ns pulse, when connected to impedance matched relativistic electron beam (REB) diode. The test facility is rated to generate RF power of ~25 MW, for charging voltage of ±50 kV. The microwave output power and dominant radiation frequency in the existing vircator are dependent on the A–K gap and charging voltage. Corresponding to the A-K gap of 5 mm and charging voltage ±15 kV, the radiated power is estimated to be ~8 MW with a dominant frequency of ~9 GHz.