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Re: Total insanity....500KW 11m amp being built.

 

I think Luke and John will get it working before
SpaceX arrives on Mars, both projects have the
potential to make a big BOOM!
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Here's a theoretical design using a 4CX3000A as a driver:
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Redesigned 100KW PEP 11M AM/SSB Amplifier
1. Block Diagram
  • Exciter: Yaesu FT-101E transceiver (27 MHz, 11-meter band).
  • Intermediate Amplifier: 4CX3000A tetrode amplifying the FT-101E output to drive the 4CW-100,000E.
  • Final Amplifier: 4CW-100,000E tetrode delivering high-power output.
  • Power Supply: High-voltage supplies for both tubes, plus filament and bias.
  • Output Network: Matches the 4CW-100,000E output to a 50-ohm antenna.
  • Cooling: Forced air for the 4CX3000A, water cooling for the 4CW-100,000E.
2. Operating Modes
  • AM: Carrier with amplitude modulation (plate modulation on the final stage).
  • SSB: Single-sideband operation (linear amplification through all stages).
Component Details
Exciter: Yaesu FT-101E
  • Output Power:
    • AM: ~50 W carrier (unmodulated), ~200 W PEP (100% modulation).
    • SSB: ~100 W PEP.
  • Frequency: 27 MHz (11-meter band; assumes modification or original CB capability).
  • Output Impedance: 50 ohms.
  • Modulation: Built-in AM/SSB modulator.
Intermediate Stage: 4CX3000A
The 4CX3000A is a forced-air-cooled tetrode with substantial power capacity, often used in broadcast and industrial applications.
  • Maximum Plate Dissipation: 3,000 W.
  • Plate Voltage: 4–6 kV (typical operating range).
  • Output Power:
    • AM: ~2,000–2,500 W carrier, ~8,000–10,000 W PEP (Class B, 60-70% efficiency).
    • SSB: ~3,000–4,000 W PEP (Class AB1, linear mode).
  • Gain: ~13-15 dB (20-30x power gain).
  • Input Power Required:
    • For 2,000 W output: ~80-100 W (matches FT-101E AM/SSB output).
    • For 3,000–4,000 W PEP: ~120-200 W (slightly above FT-101E SSB output; assumes slight overdrive or additional preamp).
  • Cooling: Forced air (~200-300 CFM, per Eimac specs).
  • Matching: Pi-network to transition from 50 ohms (FT-101E) to the 4CW-100,000E grid impedance.
Design Notes:
  • Operate in Class B for AM efficiency or Class AB1 for SSB linearity.
  • Plate voltage: 5 kV, ~600-800 mA plate current.
  • Screen voltage: 500-700 V.
Final Amplifier: 4CW-100,000E
  • Plate Voltage: 15 kV (conservative, below 20 kV max).
  • Plate Dissipation: 100 kW max (targeting 50-70% of capacity for reliability).
  • Gain: ~15-20 dB (30-100x power gain, depending on conditions).
  • Input Power Required:
    • Estimated 1-2 kW for 50-70 kW output (based on gain).
  • Cooling: Water-cooled, 20-30 GPM.
Modulation:
  • AM: Plate modulation via a 50-70 kW audio amplifier (external to FT-101E).
  • SSB: Linear amplification (no additional modulation needed).
Power Supply:
  • 4CX3000A:
    • Plate: 5 kV, 1 A (~5 kW).
    • Screen: 700 V, 100 mA.
    • Filament: 7.5 V, 21 A.
  • 4CW-100,000E:
    • Plate: 15 kV, 5-7 A (75-105 kW average).
    • Screen: 1.5 kV, 100 mA.
    • Filament: 7.5 V, 250 A.
  • Bias: Adjustable -200 to -300 V for both tubes.
Output Network:
  • Pi-network or tank circuit to match the 4CW-100,000E’s high-impedance output to a 50-ohm antenna.
  • Components: High-voltage capacitors (500 pF, 20 kV) and inductors (~1-2 ?H).
Power Output Forecast
Assumptions:
  1. Efficiency:
    • 4CX3000A: 60% (Class B, AM), 50% (Class AB1, SSB).
    • 4CW-100,000E: 70% (Class C, AM carrier), 60% (Class AB, SSB).
  2. Gain:
    • 4CX3000A: 14 dB (25x, midpoint of 13-15 dB range).
    • 4CW-100,000E: 17 dB (50x, midpoint of 15-20 dB range).
  3. Modulation: AM uses plate modulation on the final stage; SSB is linear amplification.
AM Mode:
  • FT-101E Output: 50 W carrier.
  • 4CX3000A Output:
    • Input: 50 W.
    • Gain: 14 dB → 50 × 25 = 1,250 W.
    • Adjusted: ~2,000 W carrier (60% efficiency, 5 kV, ~670 mA plate current, within tube limits).
  • 4CW-100,000E Output:
    • Input: 2,000 W carrier.
    • Gain: 17 dB → 2,000 × 50 = 100,000 W (100 kW) carrier.
    • Adjusted: ~70 kW carrier (70% efficiency, 15 kV, ~6.7 A plate current, near tube dissipation limit).
  • Modulation: 100% plate modulation.
    • PEP = 4 × carrier = 4 × 70 kW = 280 kW.
    • RMS = carrier power = 70 kW (unmodulated).
AM Output:
  • RMS: 70 kW (carrier).
  • PEP: 280 kW (100% modulation).
SSB Mode:
  • FT-101E Output: 100 W PEP.
  • 4CX3000A Output:
    • Input: 100 W PEP.
    • Gain: 14 dB → 100 × 25 = 2,500 W PEP.
    • Adjusted: ~3,000 W PEP (Class AB1, 50% efficiency, within linear limits).
  • 4CW-100,000E Output:
    • Input: 3,000 W PEP.
    • Gain: 17 dB → 3,000 × 50 = 150,000 W (150 kW) PEP.
    • Adjusted: ~100 kW PEP (60% efficiency, Class AB, near tube capability).
SSB Output:
  • RMS: ~25 kW (average power for SSB voice, ~25% of PEP).
  • PEP: 100 kW.
Final Specifications
  • Frequency: 27 MHz (11-meter band).
  • Power Output:
    • AM: 70 kW RMS (carrier), 280 kW PEP.
    • SSB: 25 kW RMS (average), 100 kW PEP.
  • Exciter: Yaesu FT-101E (50 W AM carrier, 100 W SSB PEP).
  • Intermediate Stage: 4CX3000A (~2,000 W AM carrier, 3,000 W SSB PEP).
  • Final Stage: 4CW-100,000E (70 kW AM carrier, 100 kW SSB PEP).
  • Cooling: Forced air (4CX3000A, 200-300 CFM), water (4CW-100,000E, 20-30 GPM).
  • Power Supply: Multi-voltage (5 kV for 4CX3000A, 15 kV for 4CW-100,000E).
Comparison to a 4CX1500B Driver Design
  • 4CX3000A vs. 4CX1500B:
    • Higher output (2,000 W vs. 1,000 W AM carrier; 3,000 W vs. 1,500 W SSB PEP).
    • Increased drive to the 4CW-100,000E, raising final output (70 kW vs. 50 kW AM carrier; 100 kW vs. 70 kW SSB PEP).
  • Trade-offs: Requires more cooling (200-300 CFM vs. 150 CFM), higher plate voltage (5 kV vs. 3 kV), and increased power supply demands.
Practical Notes
  1. Tuning: Precise matching networks are critical for stability, especially with the higher drive levels.
  2. Linearity: The 4CX3000A in Class AB1 ensures good SSB performance; AM uses Class B in the intermediate stage and Class C in the final stage with plate modulation.
  3. Legality: 70 kW AM or 100 kW SSB far exceeds 11-meter limits (4 W AM, 12 W PEP SSB in the U.S.). This is for experimental or licensed high-power use only.
  4. Tube Limits: The 4CW-100,000E is pushed near its 100 kW dissipation limit in AM mode (70 kW carrier + modulation peaks); ensure adequate cooling and duty cycle management.
  5. Verification: Exact output depends on tuning, tube condition, and drive—consult data sheets for precision.
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