3CX3000A7High-Mu Power Triode T he Svetlana™ 3CX3000A7 is a highperformance ceramic/metal power triode designed for use in zero-bias, class AB, or class B RF or audio amplifiers. A modern mesh filament is used, replacing the old-fashioned hairpin construction. The improved mesh filament design ensures better mechanical rigidity and long lasting concentricity of the filament, providing enhanced linearity, less noise, reduced warm-up variation and longer life. The lowinductance, mesh-filament basket also forms a natural extension of the cylindrical stem geometry into the active area, giving superior VHF performance. The Svetlana 3CX3000A7 is manufactured in the Svetlana Electron Devices complex in St. Petersburg, Russia. Svetlana has achieved the improved performance described above with exact replacement compatibility with the 3CX3000A7 manufactured in the United States. Svetlana ELECTRON DEVICES Svetlana 3CX3000A7 General Characteristics Electrical Filament Voltage Current @ 7.5 4800 0.6 24.0 24.25 2.156 in.2 lb) Cathode-Driven Radio Frequency Linear Amplifier.5 160 V A 38.50V Amplification factor (average) Direct interelectrode capacitances (grounded grid): Input Output Feedback Direct interelectrode capacitances (grounded filament): Input Output Feedback Maximum frequency for full ratings (CW) Thoriated-tungsten mesh 7.6 pF pF pF 38.35 1.61 420 2285 6030 1210 47.37 51.0 110 pF pF pF MHz Mechanical Cooling Base Socketing Operating positionVertical.0 .) 2.0 0.60 mm (9.35 2.000 in.0 0. Base up or down Maximum operating temperature Maximum dimensions: Length Diameter Net weight Forced air Coaxial Via spring collets 250˚ C 228.50 ±0.46 293 2275 6000 1720 50.5 4000 225 V A W W 4800 0.) 105.60 410 2775 7266 1425 46.56 mm (4.68 0 0. Class AB2 Maximum Ratings DC plate voltage DC plate current Plate dissipation Grid dissipation 5000 2.00 0 0.8 kg (6.00 0 0.3 V A A V A W W W Ohms Ohms Typical Operation (Frequencies to 30MHz) Plate Voltage Zero-signal plate current* Single-tone plate current Grid bias Single-tone grid current* Peak driving power Plate dissipation Single-tone plate output power Resonant load impedance Driving impedance *Approximate values Page 1 4000 0. 58 190 115 1850 10.5 4000 225 V A W W 4800 -60 1. CW or FM Maximum Ratings DC Plate voltage DC Plate current Plate dissipation Grid dissipation 5000 2.High-Mu Power Triode Cathode-Driven Class C RF Amplifier. Class AB2 Grid Driven Maximum Ratings (per tube) DC plate voltage DC plate current Plate dissipation Grid dissipation Typical Operation (two tubes. sinusoidal waveform) Plate voltage Zero-signal plate current* Maximum-signal plate current Maximum-signal grid current* Peak AF grid voltage** Peak driving power Maximum-signal plate dissipation Plate output power Load resistance (plate-to-plate) *Approximate values **Per tube Page 2 .58 0.50 3.5 3000 225 V A W W 4000 0.42 220 310 985 3300 Audio Frequency Amplifier or Modulator.48 267 435 1480 5500 V V A A V W W W 5000 2.54 0.30 0.500 2720 V A A A V W W W Ohms Typical operation (Frequencies to 110MHz) Plate voltage Grid voltage Plate current Grid current* Peak RF cathode voltage* Calculated driving power* Plate dissipation Useful output power 3500 -50 1. 0 pF pF pF 30.687 9.375 0.000 0.15 42. 54.0 0.0 28.687 0.156 B C D E F G H J K L N P Q 19.92 41.80 34. A B Q M N L P J Grid Contact K F Filament Contacts G D E C Page 3 H A Millimeters Min.625 0.250 3. 48.0 1.83 21.08 20.063 1.813 .187 8.813 1.875 2.391 3.60 17.72 98.0 A 30. Ib = 1.990 0.0 — 45.0 45.010 0.28 9.510 3.20 228.45 20.0 1.0 Max.43 107.094 4.56 Inches Min.85 38.615 1.5V Interelectrode capacitances (Grounded-Grid Connection) Input Output Feedback Interelectrode capacitances (Grounded-Filament Connection) Input Output Feedback Zero-Bias plate current (Eb = 5000V) Cut-off bias (Eb = 5000V.781 2.45 15.937 1.0 20.0 0. Max.44 75.62 16.000 0.422 4.844 3.93 10.0 28.95 74.635 1.99 105.35 – 92.0 mA) Min.625 0.60 77.52 -45 pF pF pF A V 20.490 – 0.65 23.937 1.Svetlana 3CX3000A7 Range Values for Equipment Design Filament current at 7.36 — Svetlana 3CX3000A7 Outline Drawing Dimensional Data Dim. Max.85 203.95 76.80 30. 4.13 37.65 0. 103. 70 1.84 2.70 5000 Feet Air Flow CFM 50 100 Pressure Drop Inches of Water 0. Input Circuit A resonant tank circuit is recommended for grounded-grid operation. represent another 225 watts. allowance has been made in preparing this tabulation for an additional 610 watts. A separate air system is not required with base-to-anode airflow. Filament voltage. Cooling Sufficient forced-air circulation must be provided to keep the temperature of the anode core and the temperatures of the ceramic/metal seals below 250˚C. Page 4 .00 * Because the power dissipated by the filament represents about 385 watts and because grid dissipation can.60 1.50 volts.72 1. more airflow will be required. should be maintained within 5% of this value to obtain maximum tube life. 1 When air is supplied in the anode-to-base direction. under some conditions. Mechanical Application Mounting The 3CX3000A7 must be mounted with its axis vertical. This technique increases linearity and output power. as measured at the filament collets. The base of the tube may be up or down. Airflow requirements to maintain these temperatures below 225˚C with an inlet-air temperature of 40˚C are tabulated. At frequencies above 30 MHz or at higher inlet-air temperatures. a minimum of 3 cfm must be directed into the filament-stem structure between the inner and outer filament terminals to maintain the base seals below 250˚ C.45 Anode-to-Base Air Flow 1 * Anode Dissipation Watts 2500 4000 Sea Level Air Flow CFM 42 84 Pressure Drop Inches of Water 0.High-Mu Power Triode Electrical Application Filament Operation The rated filament voltage for the 3CX3000A7 is 7. Filament Connections The Svetlana 3CX3000A7 filament connections require spring collets designed for a contact surface temperature of 250˚C and with adequate symmetrical contact surface area for the filament and RF current. Base-to-Anode Air Flow * Anode Dissipation Watts 2500 4000 Sea Level Air Flow CFM 36 67 Pressure Drop Inches of Water 0. In a single-ended circuit the loaded “Q” should be at least 3.20 5000 Feet Air Flow CFM 43 80 Pressure Drop Inches of Water . 0 9 10 4000 .Page 6 -50 0 50 100 150 200 250 300 0 1000 3.5 Volts Svetlana 3CX3000A7 Typical Constant Current Charicteristics 5000 Svetlana 3CX3000A7 GRID VOLTAGE (VOLTS) .400 1.Amperes Ef = 7. 5 1 2 3 4 6 5 7 8 Plate Current .0 1.200 .001 .5 3000 PLATE VOLTAGE (VOLTS) 2000 2.0 .500 .750 .05 .100 .Amperes Grid Current . 0 3000 9 10 PLATE TO GRID VOLTAGE (VOLTS) 2000 2.Amperes Svetlana 3CX3000A7 Svetlana 3CX3000A7 Typical Constant Current Charicteristics Typical Constant Current Curves 5000 High-Mu Power Triode Page 7 .100 .0 1000 .200 .0 5 .001 .400 .750 1.500 .0 4000 . 5 1 2 3 4 6 5 7 8 Grounded Grid Ef = 7.5 Volts Plate Current .CATHODE TO GRID VOLTAGE (VOLTS) 50 0 -50 -100 -150 -200 -250 -300 0 3.Amperes Grid Current .