TUBE: KT88
FICHIER SOURCE: sheets/084/k/KT88.pdf
FABRICANT: Genalex (GEC, distribué par British Industries Corporation, USA)
ANNEE: MARCH 1959 (Issue 2)
TYPE DECLARE: BEAM PENTODE (6.3V indirectly heated) — [en réalité beam tetrode, voir note typologie]

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Genalex — KT88 — BEAM PENTODE — 6.3V INDIRECTLY HEATED — ISSUE 2, MARCH 1959
The KT88 has an anode dissipation of 35W, primarily designed for output stage of a.f. amplifier; two valves provide up to 100W output. Intermittent conditions: 150W in Class B. Also suitable as series valve in 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
Pinout (view from underside of base):
  Pin 1 = s (base shell)
  Pin 2 = h (heater)
  Pin 3 = a (anode)
  Pin 4 = g2 (screen)
  Pin 5 = g1 (control grid)
  Pin 6 = h (heater - labeled h near pin6/7 area)
  Pin 7 = h (heater)
  Pin 8 = k, bp (cathode + beam plates)
HEATER:
  Vh ... 6.3 V
  Ih ... 1.6 A
MAXIMUM RATINGS:
  Va ......... 600 V
  Vg2 ........ 600 V
  *Va,g2 ..... 600 V
  Pa ......... 35 W
  Pg2 ........ 6 W
  *Pa+g2 ..... 40 W
  Ik ......... 175 mA
  Vh-k ....... 150 V
  Rg-k (cathode bias) ... 220 kΩ †
  Rg-k (fixed bias) ..... 100 kΩ †
  *Triode connection.   †Resistors of 20% tolerance may be used.
CAPACITANCES:
  Cg-a ... 1.2 pF (Cga)
  Cin .... 16 pF
  Cout ... 12 pF
CHARACTERISTICS:
Pentode Connection:                Triode Connection:
  Va ...... 250 V                    Va,g2 ... 250 V
  Vg2 ..... 250 V                    Ih ...... 160 mA
  Ia ...... 140 mA                   gm ...... 12 mA/V
  gm ...... 11 mA/V                  ra ...... 670 Ω
  ra ...... 12 kΩ                    µ ....... 8
  µg1-g2 .. 8

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TYPICAL OPERATION:
Push-Pull Ultra-Linear. Cathode Bias.:
  Va(b) ............ 500 V
  Va,g2 ............ 425 V
  Ia+g2(o) ......... 2x87 mA
  Ia+g2(max sig) ... 2x100 mA
  Pa+g2(o) ......... 2x40 W
  Pa+g2(max sig) ... 2x18 W
  Rk ............... 2x525 ±5% Ω
  Vg1 (approx) ..... -50 V
  Vin(g-g) ......... 90 V
  RL(a-a) .......... 6 kΩ
  zout ............. 4.5 kΩ
  Pout ............. 50 W
  D ................ 1 %
  Intermodulation .. 5 %
Push-Pull Ultra-Linear. Fixed Bias.:
  Va(b) ............ 560 V
  Va,g2 ............ 550 V
  Ia+g2(o) ......... 2x50 mA
  Ia+g2(max sig) ... 2x150 mA
  Pa+g2(o) ......... 2x30 W
  Pa+g2(max sig) ... 2x33 W
  Vg1 (approx) ..... -80 V
  Vin(g-g) ......... 120 V
  RL(a-a) .......... 4.5 kΩ
  zout ............. 6.5 kΩ
  Pout ............. 100 W
  D ................ 3-6 %
  Intermodulation .. 12 %
  *A negative bias range of 70±25% is recommended.
Push-Pull Triode Connection. Cathode Bias.:   (col1 / col2)
  Va(b) ............ 400 / 485 V
  Va,g2 ............ 350 / 425 V
  Ia+g2(o) ......... 2x67 / 2x85 mA
  Ia+g2(max sig) ... 2x72 / 2x90 mA
  Pa+g2(o) ......... 2x24 / 2x40 W
  Rk ............... 2x525±5% / 2x525±5% Ω
  Vg1 (approx) ..... -38 / -48 V
  Vin(g-g) ......... 60 / 70 V
  RL(a-a) .......... 4 / 4 kΩ
  zout ............. 2.5 / 2.5 kΩ
  Pout ............. 15 / 27 W
  D ................ 1-3 / 1-3 %
  Intermodulation .. 6 / 6 %
INSTALLATION: May be mounted horizontally only if pins 4 and 8 are in a vertical plane. Free air circulation desirable; hottest part of bulb should not exceed 250°C.

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[courbes seules — Ia(mA) vs Va(V), Vg2=300V, Vg1=0 à -45V, ligne Pa=35W, Ig2 at Vg1=0V]

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[courbes seules — Ia(mA) vs Va(V), Vg2=200V, Vg1=0 à -25V, ligne Pa=35W]

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[courbes seules — Ia(mA) vs Va(V), Vg2=100V, Vg1=0 à -15V]

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[courbes seules — Ia(mA) vs Va(V), Vg1=0V, Vg2=100 à 300V, ligne Pa=35W, Ig2 at Vg2=100-300V]

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[courbes seules — TRIODE CONNECTION: Ia(mA) vs Va(V), Vg1=0 à -80V, ligne Pa=40W]

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[courbes seules — ULTRA-LINEAR CONNECTION 40% TAPS: Ia(mA) vs Va/Vg2, Vb=425V, Vg1=0 à -60V]