Part Number: ECL86, PCL86
Function: Triode Pentode, Vacuum Tube
Package: Tube type
Manufacturer: RCA, Philips
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Description
The ECL86 was one of the last triode plus output pentode valves designed and was released to the market in 1962. Uses were in domestic radio and audio equipment. Normally in single ended output stages for radio-grams and tape recorders. The design proved popular in low cost stereo systems. The ECL86 was preceded by the ECL82.
The triode section serves as a low-noise audio voltage amplifier or phase amplifier, providing sufficient gain to drive the power pentode stage. The pentode is optimized for single-ended Class A audio amplification and is capable of delivering several watts of output power with good linearity and low distortion when properly biased. Its separate cathode construction allows each section to be independently optimized, improving overall amplifier performance and offering greater design flexibility compared to earlier integrated valve designs.
Key Electrical Characteristics
- Separate cathodes allow independent biasing of each section.
- Triode section provides high voltage gain for audio preamplification.
- Pentode section is optimized for low-frequency audio power amplification.
- Suitable for single-ended Class A amplifier designs.
- Capable of driving output transformers for loudspeaker applications.
- Good linearity when operated within recommended plate voltage and current limits.
- Heater designed for standard series heater supply operation.
- Excellent compatibility with conventional analog audio circuits.
- Well suited for low-to-medium power vacuum tube amplifier designs.
Pinout
Design Considerations
- Maintain proper heater voltage to ensure stable cathode emission and long tube life.
- Select appropriate plate and screen voltages according to amplifier operating conditions.
- Use separate cathode bias components for the triode and pentode sections when required.
- Choose an output transformer with the correct primary impedance for maximum performance.
- Provide adequate chassis ventilation since the valve dissipates significant heat.
- Keep high-impedance grid wiring short to minimize hum and unwanted oscillation.
- Use proper grounding techniques to reduce noise in sensitive audio circuits.
- Install quality filter capacitors in the high-voltage power supply to suppress ripple.
- Avoid exceeding maximum plate dissipation to improve reliability and tube longevity.
- Allow sufficient spacing between valves to reduce thermal interaction in multi-tube amplifiers.
Typical Circuit Configurations
- Single-ended Class A integrated audio amplifier.
- Compact stereo amplifier using one ECL86 per channel.
- Radio receiver audio output stage.
- Tape recorder playback amplifier.
- Phonograph amplifier with integrated voltage and power stages.
- Educational vacuum tube amplifier demonstration circuits.
- Vintage public-address amplifier systems.
- Retro guitar practice amplifiers with low output power.
Performance Advantages
- Reduces component count by integrating two active devices in one envelope.
- Simplifies amplifier layout and wiring.
- Produces the characteristic warm sound associated with vacuum tube amplifiers.
- Excellent linear performance for low-power audio reproduction.
- Separate cathodes provide flexible biasing options.
- Well proven through decades of audio equipment applications.
- Suitable for restoration of classic European audio equipment.
- Requires relatively simple supporting circuitry.
Typical Applications
- Vintage hi-fi integrated amplifiers.
- Domestic tabletop radio receivers.
- Reel-to-reel tape recorders.
- Portable record players and phonographs.
- Compact stereo audio systems.
- Educational electronics laboratories.
- Vacuum tube restoration projects.
- Custom boutique audio amplifiers.
- Low-power musical instrument amplifiers.
- Collector-grade reproduction audio equipment.
Comparison with Similar Components
| Device | Main Difference | Typical Use |
|---|---|---|
| ECL82 | Earlier generation with lower output capability. | Compact radio and audio amplifiers. |
| PCL86 | Electrically similar but designed for a different heater voltage. | Television and audio equipment with series heater strings. |
| ECL805 | Primarily intended for television vertical deflection applications. | TV circuits and specialized amplifier designs. |
| EL84 + ECC83 | Uses separate power and preamplifier tubes for higher flexibility. | Higher-performance hi-fi and guitar amplifiers. |
Frequently Asked Questions
Q1. Can the ECL86 replace an ECL82 directly?
Not always. Although both are triode-pentode valves, their electrical characteristics, operating conditions, and circuit requirements differ, so direct substitution is generally not recommended without circuit modifications.
Q2. What factors most affect the reliability of an ECL86 amplifier?
Proper heater voltage, controlled plate dissipation, adequate cooling, quality power supply filtering, and correct bias adjustment are the primary factors influencing long-term reliability.
Q3. What should be considered when laying out an amplifier using the ECL86?
Keep signal paths short, separate high-voltage wiring from low-level audio signals, use effective grounding techniques, and position the output transformer to minimize magnetic hum coupling.
ECL86 PDF Datasheet
