Tube was tested in typical point: Ua = 250 V, Ug = -8,5 V. Measurement results: Ia1 = 13,2 mA, gm1 = 2,6 mA/V; Ia2 = 12,4 mA, gm2 = 2,5 mA/V. Transconductance has been measured by the change grid voltage from -8,5 V to -8,0 V and reading anode current. Tube was tested with stabilised power supplies and calibrated multimeters.