KT88 tube data (electron valve/beam power tetrode/output Beam pentode)General InformationThe KT88 can be either a beam power tetrode or output beam pentode depending on the circuit. It has a high anode dissipation rating. Enhanced sonic performance, including: increased peak cathode emission, stable operation. Can be used as direct replacement for KT9o, KT99 and 6550. MAXIMUM RATINGSHeater Voltage 6.3 V Vh Heater Current 1.8 A Ih Maximum Anode Voltage 800 V Va(max) Maximum Screen grid voltage 600 V Vg2(max) Maximum Control Grid Voltage -300 V Vg1(max) Maximum Voltage between Grids 1&2 400 V Vg1-g2(max) Maximum Anode Dissipation 42 W Pa(max) Maximum Screen Dissipation 8 W Pg2(max) Maximum Cathode Current 230 mA Ik(max) Maximum Heater to Cathode Voltage 250 V Vh-k(max) (DC Heater negative) Maximum Heater to Cathode Voltage 250 V Vh-k(max) (DC Heater positive CHARACTERISTICSPentode Connection Triode Connection Va 250V Va,g2 450V Vg2 250V Vg1 -46V Ia 140mAg gm 13mA/V Ra 12kΩ ra 6.5kΩ µg1-g2 8 µ 8 TYPICAL OPERATION CLASS APush-Pull, Ultra Linear, Cathode Bias (Data per pair) Va,g2 335V 425V Ia+g2 (0) 80mA 174mA Ia+g2 (Max sig) 85mA 200mA Pa+g2 (0) 27w 80W Pa+g2 (Max sig) 12W 36W Rk (per valve) 400Ω 525Ω Vg (approx) -32V -50V P out 30W 50W* RL (a-a) 5K Ω 6kΩ D 1% 2*% * These figures refer to an average pair. With a matched pair the distortion will be reduced and with an unmatched pair it may rise to 4%. Push-Pull, Ultra Linear, Fixed Bias (Data per pair) Va,g2 450V 550V Ia+g2 (0) 100mA 100mA Ia+g2 (Max sig) 240mA 300mA Pa+g2 (Max sig) 40W 66W *Vg -65V -80V P out 65W 100W* RL (a-a) 4kΩ 4.5kΩ Z out 6.5kΩ 6.5kΩ †D 3 to 6% 3 to 6% * A bias voltage range of at least 25% is recommended. † The distortion will vary according to the degree of matching INTER-ELECTRODE CAPACITANCES (Pf)Grid/Earth 16 c in Anode/Earth 12 c out Anode/Grid 1.2 cg-a Without external shielding DIMENSIONSMaximum overall length 125 mm Maximum seated height 110 mm Maximum diameter 52 mm Net weight g BASE – Metal – Octal Click here for information about replacing a KT88 Beam Tetrode with a 12E1 Beam Terode
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