TUBE: 75TL
FICHIER SOURCE: sheets/140/7/75TL.pdf
FABRICANT: EIMAC, Division of Varian, San Carlos, California
ANNEE: 1967 (Revised 4-1-67, Copyright 1952, 1967 Varian)
TYPE: Low-Mu Triode — Modulator / Oscillator / Amplifier

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75TL — LOW-MU TRIODE — MODULATOR / OSCILLATOR / AMPLIFIER
EIMAC — Division of Varian — SAN CARLOS, CALIFORNIA

The EIMAC 75TL is a low-mu power triode intended for use as an amplifier, oscillator, or
modulator. Maximum plate dissipation 75 watts, maximum plate voltage 3000 volts at frequencies
up to 40 MHz. Forced-air cooling not required below 40 MHz.
Class-C RF: up to 225 watts plate power output with 8 watts driving power.
Two 75TL's in Class-B modulator: up to 350 watts max-signal plate power output, 5 watts driving.

GENERAL CHARACTERISTICS
ELECTRICAL
Filament: Thoriated tungsten
  Voltage ............ 5.0 volts
  Current ............ 6.25 amperes
Amplification Factor (Average) ... 12
Direct Interelectrode Capacitances (Average)
  Grid-Plate ......... 2.4 pF
  Grid-Filament ...... 2.6 pF
  Plate-Filament ..... 0.4 pF
Transconductance (Ib=225 ma., Eb=2500v.) ... 3350 umhos
Highest Frequency for Maximum Ratings ... 40 MHz

MECHANICAL
Base ......... Medium 4-pin bayonet
Basing ....... See outline drawing
Socket ....... Johnson type No. 122-224, National type No. XC-4 or CIR-4, or equivalent
Mounting Position ... Vertical, base down or up
Cooling ............ Convection and radiation
Maximum Temperature of Plate and Grid Seals ... 225 deg C
Recommended Heat Dissipating Connectors:
  Plate ... EIMAC HR-3
  Grid .... EIMAC HR-2
Maximum Overall Dimensions:
  Length ... 7.25 inches
  Diameter . 2.81 inches
Net Weight ... 3 ounces
Shipping Weight (Average) ... 1.5 pounds

RADIO FREQUENCY POWER AMPLIFIER AND OSCILLATOR
Class-C Telegraphy (Key-down conditions, 1 tube)
MAXIMUM RATINGS (Frequencies up to 40 MHz)
  DC Plate Voltage ...... 3000 volts
  DC Plate Current ...... 225 ma.
  Plate Dissipation ..... 75 watts
  Grid Dissipation ...... 13 watts
TYPICAL OPERATION (Frequencies up to 40 MHz)
  DC Plate Voltage ...... 1000 / 1500 / 2000 volts
  DC Grid Voltage ....... -150 / -250 / -300 volts
  DC Plate Current ...... 215 / 167 / 150 ma.
  DC Grid Current ....... 28 / 22 / 21 ma.
  Peak RF Grid Input Voltage (approx.) ... 320 / 355 / 425 volts
  Driving Power (approx.) ... 8 / 6 / 8 watts
  Plate Power Input ..... 215 / 250 / 300 watts
  Plate Dissipation ..... 75 / 75 / 75 watts
  Plate Power Output .... 140 / 175 / 225 watts

PLATE MODULATED RADIO FREQUENCY AMPLIFIER
Class-C Telephony (Carrier conditions, per tube)
MAXIMUM RATINGS (Frequencies up to 40 MHz)
  DC Plate Voltage ...... 2400 volts
  DC Plate Current ...... 180 ma.
  Plate Dissipation ..... 50 watts
  Grid Dissipation ...... 13 watts
TYPICAL OPERATION (Frequencies up to 40 MHz)
  DC Plate Voltage ...... 1000 / 1500 / 2000 volts
  Total Bias Voltage .... -250 / -370 / -500 volts
  Fixed Bias Voltage .... -130 / -260 / -380 volts
  Grid Resistor ......... 7500 / 6000 / 6000 ohms
  DC Plate Current ...... 135 / 130 / 130 ma.
  DC Grid Current (approx.) ... 16 / 18 / 20 ma.
  Peak RF Grid Input Voltage (approx.) ... 410 / 545 / 695 volts
  Driving Power (approx.) ... 6 / 10 / 14 watts
  Grid Dissipation ...... 2 / 3 / 4 watts
  Plate Power Input ..... 135 / 195 / 260 watts
  Plate Dissipation ..... 50 / 50 / 50 watts
  Plate Power Output .... 85 / 145 / 210 watts

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AUDIO FREQUENCY POWER AMPLIFIER AND MODULATOR
Class-AB1
MAXIMUM RATINGS (Per tube)
  DC Plate Voltage ...... 3000 volts
  Max-Signal DC Plate Current ... 225 ma.
  Plate Dissipation ..... 75 watts
TYPICAL OPERATION (Sinusoidal wave, two tubes unless otherwise specified)
  DC Plate Voltage ...... 1500 / 2000 volts
  DC Grid Voltage ....... -130 / -190 volts
  Peak AF Grid Input Voltage (per tube) ... 130 / 190 volts
  Zero-Signal DC Plate Current ... 67 / 50 ma.
  Max-Signal DC Plate Current ... 143 / 130 ma.
  Driving Power .......... 0 / 0 watt
  Effective Load, Plate-to-Plate ... 10,200 / 21,200 ohms
  Max-Signal Plate Power Output ... 64 / 110 watts
  Max-Signal Plate Dissipation (per tube) ... 75 / 75 watts
  Total Harmonic Distortion ... 3.0 / 3.5 per cent

AUDIO FREQUENCY POWER AMPLIFIER AND MODULATOR
Class-AB2
MAXIMUM RATINGS (Per tube)
  DC Plate Voltage ...... 3000 volts
  Max-Signal DC Plate Current ... 225 ma.
  Plate Dissipation ..... 75 watts
  Grid Dissipation ...... 13 watts
TYPICAL OPERATION (Sinusoidal wave, two tubes unless otherwise specified)
  DC Plate Voltage ...... 1000 / 1500 / 2000 volts
  DC Grid Voltage1 ...... -70 / -130 / -190 volts
  Zero-Signal DC Plate Current ... 100 / 67 / 50 ma.
  Max-Signal DC Plate Current ... 350 / 285 / 250 ma.
  Max-Signal Avg. Driving Power (approx.) ... 7 / 6 / 5 watts
  Max-Signal Peak Driving Power ... 26 / 23 / 19 watts
  Effective Load, Plate-to-Plate ... 5300 / 11,000 / 18,000 ohms
  Max-Signal Plate Power Output ... 200 / 280 / 350 watts
  Max-Signal Plate Dissipation (per tube) ... 75 / 75 / 75 watts
  Total Harmonic Distortion ... 2.0 / 4.5 / 6.0 per cent
1 Adjust to give stated zero-signal plate current. Effective grid-circuit resistance per tube must not exceed 250,000 ohms in class-AB1 operation.

APPLICATION — MECHANICAL / ELECTRICAL text.
Filament Voltage: rated 5.0 volts, range 4.75 to 5.25 volts.
Plate Voltage: should not exceed 3000 volts.
Grid Dissipation: must not exceed 13 watts. Pg = ecmp*Ic.
Plate Dissipation: visibly red at maximum rated 75 watts.

OUTLINE DRAWING / BOTTOM VIEW:
Medium 4 pin bayonet base. Bottom view pins 1,2,3,4 (pins 2 & 3 at top, pins 1 & 4 at bottom).
GRID and PLATE connections. 2 pins .125±.003, 2 pins .156±.003.

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[courbes seules — pas de donnees tabulaires]
DRIVING POWER vs. POWER OUTPUT — three charts at Eb = 1000, 1500, 2000 volts.

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[courbes seules — pas de donnees tabulaires]
EIMAC 75TL CONSTANT-CURRENT CHARACTERISTICS — Plate Current (amperes) / Grid Current (milliamperes),
Grid Voltage vs Plate Voltage. Plate current 0 to 1.6 A; grid current 0 to 350 ma. (Single-grid triode confirmed.)