RF Power Grid Tubes · Triodes
TH781 Thomson/Thales HF Triode
Available on request
Thomson / Thales
TH781
Compact Thomson/Thales triode with 600 W plate dissipation for HF linear amplifiers and VHF transmitter driver stages.
- Plate Dissipation
- 600 W
- Max Frequency
- 500 MHz
- Max Plate Voltage
- 3.5 kV
- Max Plate Current
- 0.5 A
Worldwide shipping
Cross-reference support
Grunius BV · Groningen, NL
TH781
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About the TH781
The TH781 is a power triode manufactured by Thomson / Thales. Compact Thomson/Thales triode with 600 W plate dissipation for HF linear amplifiers and VHF transmitter driver stages.
Key ratings of the TH781 include tube type Triode, plate dissipation 600 W, max plate voltage 3.5 kV, max plate current 0.5 A, max frequency 500 MHz and filament voltage 6.3 V.
Typical applications are HF driver stages, VHF low-power amplifiers, scientific RF oscillators and european radio transmitters. Notable features: 600 W plate dissipation, 500 MHz capable, compact form factor and thomson heritage design.
Power triodes are three-electrode grid tubes used as RF oscillators and amplifiers in industrial RF heating (plastic welding, induction heating, drying), RF-excited CO₂ lasers, broadcast transmitters and particle accelerators. In oscillator service they work with vacuum capacitors in the tank and matching circuits.
PartnerTubes supplies the TH781 worldwide from Groningen, the Netherlands — availability, lead time and price are confirmed per enquiry. Our team can help with equivalent and cross-reference types, sockets and accessories, and supply programmes for OEM and maintenance customers. Interchangeability must always be confirmed for the specific equipment.
Technical specifications
| Tube Type | Triode |
|---|---|
| Plate Dissipation | 600 W |
| Max Plate Voltage | 3.5 kV |
| Max Plate Current | 0.5 A |
| Max Frequency | 500 MHz |
| Filament Voltage | 6.3 V |
| Filament Current | 5.0 A |
| Cooling | Forced air |
Specifications are indicative and based on published manufacturer data. Always verify against the official datasheet and confirm suitability for your application before ordering.
Applications & features
Used in
- HF driver stages
- VHF low-power amplifiers
- Scientific RF oscillators
- European radio transmitters
Key features
- 600 W plate dissipation
- 500 MHz capable
- Compact form factor
- Thomson heritage design
Related parts & equivalents
Recommended alongside or as alternatives to the TH781.
Similar RF Power Grid Tubes
Comparable type, ratings, manufacturer or applications.
Vacuum capacitors for tank & matching circuits
Often ordered with the TH781 for the same system.
Jennings UCSL 25–200 pF Variable Vacuum Capacitor 25 kV
Jennings Technology (CPI)
Capacitance Range 25–200 pF
Frequently asked questions
What is the TH781?
The TH781 is a power triode manufactured by Thomson / Thales. Compact Thomson/Thales triode with 600 W plate dissipation for HF linear amplifiers and VHF transmitter driver stages.
What are the specifications of the TH781?
Tube Type: Triode; Plate Dissipation: 600 W; Max Plate Voltage: 3.5 kV; Max Plate Current: 0.5 A; Max Frequency: 500 MHz; Filament Voltage: 6.3 V; Filament Current: 5.0 A; Cooling: Forced air.
What is the TH781 used for?
The TH781 is used in HF driver stages, VHF low-power amplifiers, scientific RF oscillators and european radio transmitters.
What are alternatives or related parts to the TH781?
Related and comparable parts include TH308, 8877, GU-74B, CTK 12-1, RS 1034SK and RS 1094L. Contact PartnerTubes to confirm interchangeability for your equipment.
Where can I buy the TH781?
The TH781 is available from PartnerTubes (Grunius BV, Groningen, Netherlands) with worldwide shipping. Availability and lead time are confirmed on request. Request a quote at https://www.partnertubes.com/contact/?part=TH781 or email info@partnertubes.com.