KT&88 ISSUE 2 MARCH, 1959 BEAM PENTODE 63V INDIRECTLY HEATED Genalex The KT88 has an anode dissipation of 35W and is primarily designed for the output stage of an a.f. amplifier for which two valves will provide up to 100W output. Under intermittent conditions, an output of 150W is obtainable in Class B (see Circuit Supplement). It is also suitable for use as a series valve in a stabilised power supply. BASE CONNECTIONS AND VALVE DIMENSIONS Base : Metal shell wafer octal. Bulb : Tubular Max. overall length : 125 mm. Max. seated length : 110 mm. Max. diameter : 52 mm. View from underside of base. HEATER Vh 6-3 Vv Th 1-6 A MAXIMUM RATINGS Va 600 Vv Veo 600 Vv *Vag2 600 Vv Pa 35 WwW Peg2 6 Ww *Da+g2 40 WwW Ix 175 mA Vbk 150 Vv Rgk (cathode bias) 220+ kQ Rg k (fixed bias) 100+ kQ *Triode connection. +Resistors of 20% tolerance may be used. CAPACITANCES Cgoa 1-2 pk Cin 16 pl Cout 12 pF CHARACTERISTICS Pentode Connection Triode Connection Va 250 Vv Vaig2 250 Vv Vg2 250 Vv Th 160 mA Ig 140 mA gm 12 mA/V gm 1k mA/V Ta 670 Q Ya 12 kQ uw 8 a gl g2 8 Distributors : BRITISH INDUSTRIES CORPORATION 80 Shore Road, Port Washington, New York, U.S.A. Representing : THE GENERAL ELECTRIC CO. LTD. OF ENGLAND Head Office: Magnet House, Kingsway, London, W.C.2.KT88 TYPICAL OPERATION Push-Pull Ultra-Linear. Cathode Bias. Vatb) 500 Vv Vag2 425 Vv Ta+g2(0) 2x87 mA Ta+g2(max sig) 2x 100 mA Pa+g2(0) 2x40 WwW Pa+g2(max sig) 2x18 WwW *R_ 2x 52545% Q Vegi (approx) 50 Vv in(gg) 90 Vv 1(aa) 6 kQ Zout 4:5 kQ Pout 50 Ww D 1 % fIntermodulation 5 % *Separate bias resistors are essential. tAverage pair. Push-Pull Ultra-Linear. Fixed Bias. Va(b) 560 Vv Vaig2 550 Vv Ta+g2(0) 2x 50 mA 1, 42(max sig) 2x 150 mA Pa+g2(o) 2x30 Ww Pa+g2(max sig) 2x33 Ww *Ve1 (approx) 80 Vv Vin(gg) 120 v Rx(aa) 45 kQ Zout 65 kQ Pout 100 Ww D 36 % Intermodulation 12 % *A negative bias range of 704+25% is recommended. +The distortion will vary according to the degree of matching. Push-Pull Triode Connection. Cathode Bias. Vaib) 400 485 Vv Vag? 350 425 Vv Ta+g2(0) 2x67 2x 85 mA Ta+g2(max sig) 2x72 2x90 mA Pa+g2(0) 2x24 2x40 WwW *R_ 2x52545% 2x52545% Q Vegi (approx) 38 48 Vv Vin(gg) 60 70 Vv Ri(aa) 4 4 kQ Zout 25 2:5 kQ Pout 15 27 WwW 13 13 % Intermodulation 6 6 % *Separate bias resistors are essential. +The distortion will vary according to the degree of matching. INSTALLATION The valve may be mounted horizontally only if pins 4 and 8 are in a vertical plane. Free air circulation round the valve is desirable ; the hottest part of the bulb should not exceed 250C. bsKT88 00+ oof (n) "A 00 00! 00! 00f 00+KT88 00+ 00s (A) A 002 00! 001 002 00s 00% (yu) TKT88 0S (vu) r 001 0s!KT88 500 400 300 I, (mA) 200 100 at V,.=300V =200 0 50 100 | 200 V, (V)KT&8 00r (A) "A 00s 002 NOILSANNOD AdOlul 00! 00) (ww) T 002 00KT88 SSP SIP AS@b=A SdVL %0% NOILDINNOD YW3NIT- SLE (A) tb, See S62 $SZ 00! 002.~ (vu 00s 00+ Printed in England. C. OV.3586