TUBE: KT66
FICHIER SOURCE: sheets/086/k/KT66.pdf
FABRICANT: GEC / The M-O Valve Company Limited
ANNEE: April 1977 (Issue 5)
TYPE DECLARE: BEAM TETRODE

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THE M-O VALVE COMPANY LIMITED — GEC — KT66 — BEAM TETRODE
BRIEF DATA:
A beam tetrode with an absolute maximum anode dissipation rating of 30 W.
Designed for use in the output stage of an a.f. amplifier, or as a series valve in a stabilized power supply.
The KT66 is a commercial version of the CV1075.
HEATER:
  Heater voltage ............ 6.3 V
  Heater current (approx) ... 1.3 A
MAXIMUM RATINGS:                         Design Max   Absolute Max
  DC anode voltage ................ 500          550        V
  DC screen voltage ............... 500          550        V
  Negative dc grid voltage ........ 200          200        V
  DC cathode current .............. 200          200        mA
  Anode dissipation ............... 25           30         W
  Screen dissipation .............. 3.5          4.5        W
  *Anode and screen dissipation ... 27           32         W
  Heater-cathode voltage .......... 150          150        V
  Bulb temperature ................ 250          250        °C
  External grid-cathode resistor (cathode bias):
    Pa+g2 ≤ 27W ............ 1.0 MΩ
    Pa+g2 > 27W ............ 500 kΩ
  External grid-cathode resistor (fixed bias):
    Pa+g2 ≤ 27W ............ 250 kΩ
    Pa+g2 > 27W ............ 100 kΩ
  *Triode or ultra linear operation.
CAPACITANCES (Measured on a cold unscreened valve):
  Grid to all less anode ... 14.5 pF   (= Cin, Cg1-k+g2+...)
  Anode to all less grid ... 10.0 pF   (= Cout, Ca-k+...)
  Anode to grid ............ 1.1 pF    (= Cga, feedback)

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CHARACTERISTICS:
Tetrode Connection:
  DC anode voltage ........... 250 V
  DC screen voltage .......... 250 V
  Negative dc grid voltage ... 15 V
  Mutual conductance ......... 7 mA/V
  Internal anode resistance .. 22.5 kΩ
Triode Connection:
  DC anode voltage ........... 250 V
  Negative dc grid voltage ... 15 V
  Mutual conductance ......... 7.3 mA/V
  Internal anode resistance .. 1.3 kΩ
TYPICAL OPERATION:
Triode Connection. Class A. Single Valve. Cathode Bias.   (col1 / col2)
  Vb ............... 270 / 440 V
  Va,g2 ............ 250 / 400 V
  -Vg1 (approx) .... 20 / 38 V
  vin(pk) .......... 20 / 38 V
  Rk ............... 330 / 600 Ω
  Ia+g2(o) ......... 60 / 63 mA
  Pa+g2(o) ......... 15 / 25 W
  RL ............... 2.75 / 4.5 kΩ
  Pout ............. 2.2 / 5.8 W
  Dtot ............. 6 / 7 %
Triode Connection. Class AB1. Push-Pull. Cathode Bias.   (col1 / col2)
  Vb ............... 270 / 440 V
  Va,g2 ............ 250 / 400 V
  -Vg1 (approx) .... 19 / 38 V
  vin(g1-g1)(pk) ... 38 / 76 V
  Rk ............... 2x345 / 2x615 Ω
  Ia+g2(o) ......... 2x55 / 2x62 mA
  Pa+g2(o) ......... 2x14 / 2x25 W
  RL(a-a) .......... 2.5 / 4.0 kΩ
  Pout ............. 4.5 / 14.5 W
  Dtot ............. 2.0 / 3.5 %
  IM ............... 3.0 / 3.0 %
  Zout ............. 3.5 / 3.5 kΩ

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Tetrode Connection. Class AB1. Push-Pull. Cathode Bias:
  Vb(a)(o) ......... 450 V
  Vb(a)(max sig) ... 425 V
  Va(o) ............ 415 V
  Va(max sig) ...... 390 V
  Vg2(o) ........... 300 V
  Vg2(max sig) ..... 275 V
  -Vg1 (approx) .... 27 V
  Ia(o) ............ 2x52 mA
  Ia(max sig) ...... 2x62 mA
  Ig2(o) ........... 2x2.5 mA
  Ig2(max sig) ..... 2x9 mA
  Pa(o) ............ 2x21 W
  Pa(max sig) ...... 2x9 W
  Pg2(o) ........... 2x0.75 W
  Pg2(max sig) ..... 2x2.5 W
  Rk ............... 2x500 Ω
  RL(a-a) .......... 8 kΩ
  vin(g1-g1)(pk) ... 70 V
  Pout ............. 30 W
  Dtot ............. 6 %
Ultra-linear Connection. Push-Pull. 40% Taps. Class AB1. Cathode Bias.:
  Vb ............... 450 V
  Va,g2(o) ......... 425 V
  Va,g2(max sig) ... 400 V
  Ia+g2(o) ......... 2x62.5 mA
  Ia+g2(max sig) ... 2x72.5 mA
  Pa+g2(o) ......... 2x26.5 W
  Pa+g2(max sig) ... 2x13 W
  Rk ............... 2x560 Ω
  -Vg1 (approx) .... 35 V
  Pout ............. 32 W
  RL(a-a) .......... 7 kΩ
  Zout ............. 9 kΩ
  Dtot ............. 2 %
  IM ............... 4 %

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Ultra-linear Connection. Class AB1. Push-Pull. 40% Taps. Fixed Bias.:
  Va,g2(o) ......... 525 V
  Va,g2(max sig) ... 500 V
  Ia+g2(o) ......... 2x35 mA
  Ia+g2(max sig) ... 2x80 mA
  Pa+g2(o) ......... 2x18 W
  Pa+g2(max sig) ... 2x15 W
  -Vg1 (approx) .... 67 V
  RL(a-a) .......... 8 kΩ
  vin(g1-g1)(pk) ... 127 V
  Pout ............. 50 W
  Dtot ............. 3 %
  IM ............... 15 %
  Zout ............. 10 kΩ
LIFE PERFORMANCE: Average life at abs max ratings >= 8000 hours. At reduced rating Pa+g2=21W, >=10,000 hours.
  End of life: Pout 50% of initial; gm < 5.5 mA/V. Measured at Va=250V, Vg2=250V, Ia=85mA.
INSTALLATION: May be mounted in any position; horizontal orientated per Fig.1. Pair at max ratings >= 9cm (3.5in) between centres.
  Series resistor 100-300Ω close to screen tag for parasitic oscillation; control grid series resistor 10-50kΩ recommended.

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BASE CONNECTIONS AND VALVE DIMENSIONS:
  Base: International Octal (B8-0)
  Bulb: Dome top tubular
  Max. overall length: 135 mm
  Max. seated length: 121 mm
  Max. diameter: 53 mm
Pinout (view from underside of base):
  Pin 1 = IC (internal connection)
  Pin 2 = h (heater)
  Pin 3 = a (anode)
  Pin 4 = g2 (screen)
  Pin 5 = g1 (control grid)
  Pin 6 = NP (no pin)
  Pin 7 = h (heater)
  Pin 8 = k (cathode)
Fig.1: Correct orientation of valve socket for horizontal mounting.

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[courbes seules — Tetrode Connection Vg2=250: Anode & Screen currents (mA) vs Anode voltage, Vg1 +10 à -36. + Tetrode Connection Vg1=0: Anode current vs Anode voltage, Vg2=50 à 300]

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[courbes seules — Triode Connection: Anode plus Screen current vs Anode & Screen voltage, Vg1 0 à -120. + Tetrode Connection Vg2=300: Anode & Screen currents vs Anode voltage]

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[courbes seules — Tetrode Connection 2 valves Class AB1 Push-Pull Va(o)=415 Vg2(o)=300: Pout & D vs RL(a-a). + Triode 2 valves Va=400. + Ultra-linear circuits 40% taps Vb=400/450]