NATIONAL Water Cooled Rf Power Triode Tube 8668/YD1172/YD-1172

( Brand: National ), ( Manufacturer Part Number: 8668 ), ( Type: Power Tubes )

Review NATIONAL Electronics 8668/yd1172/yd-1172 Water cooled Rf Power Triode Tube

The **National 8668/8668 (YD1172/YD-1172) Water-Cooled RF Power Triode Tube** is a high-performance, industrial-grade vacuum tube designed for demanding applications in radio frequency (RF) power amplification, broadcasting, and high-power electronic systems. Part of the robust **8668 series**, this triode tube is engineered to deliver exceptional efficiency, reliability, and thermal stability in environments where continuous high-power output is essential. With a **maximum plate dissipation of 15 kW** and a **peak power handling capability of up to 50 kW**, the 8668 excels in transmitting systems, industrial heaters, and specialized RF amplifiers where conventional solid-state solutions fall short. Its **water-cooled construction** ensures optimal heat dissipation, preventing thermal runaway and extending the tube s operational lifespan, even under sustained high-load conditions.

The **YD1172/YD-1172 designation** (a Soviet-era equivalent) underscores its compatibility with legacy systems while maintaining modern performance standards. Featuring a **ceramic-to-metal sealed envelope** for durability and a **permanent magnet focusing system**, this tube minimizes maintenance requirements and ensures consistent beam focusing over prolonged use. The **grid control structure** is optimized for efficient RF amplification, with a **low grid current draw** to maximize power transfer while reducing energy loss. Its **high transconductance and gain** make it ideal for applications requiring precise signal amplification, such as **medium-wave (MW) and shortwave (SW) broadcasting transmitters**, industrial RF heating, and experimental high-power electronics.

Built to withstand **extreme operating conditions**, the 8668/8668 tube incorporates **robust internal construction**, including **tungsten filament cathodes** for longevity and **molybdenum plate structures** to handle the thermal stresses of high-power operation. The **water-cooling system** is designed for seamless integration with external cooling loops, allowing operators to fine-tune thermal management based on specific workload demands. This tube s **universal pin configuration** (often compatible with **813A, 4CX15000A, and other high-power triodes**) enhances its versatility, making it a sought-after component in both **restoration projects and new high-power RF systems**.

For engineers and hobbyists working in **amateur radio, vintage radio restoration, or industrial electronics**, the 8668/8668 tube represents a **bridge between classic vacuum tube technology and modern high-power requirements**. Its **reliability in demanding environments**, combined with **superior RF performance**, makes it a preferred choice for applications where **efficiency, durability, and raw power** are paramount. Whether used in **broadcast studios, experimental RF setups, or specialized industrial transmitters**, this tube delivers the **consistent, high-output performance** that defines it as a cornerstone of high-power vacuum tube amplification.

**Pros and Cons of buying a National 8668/8668-8668/yd1172/yd-1172 Water-Cooled RF Power Triode Tube**

The National 8668 (and its variants, including the 8668-8668, YD1172, and YD-1172) is a high-power RF triode tube commonly used in amateur radio, broadcast, and industrial applications. Below is a detailed analysis of its advantages and disadvantages.

---

### **Pros**

1. **High Power Handling**

The 8668 is capable of delivering significant RF power, typically in the range of **1,000 to 2,000 watts PEP (or CW)** depending on the circuit and cooling conditions. This makes it suitable for high-power amateur radio transmitters, especially in the HF bands (10m 80m).

2. **Reliability and Durability**

As a water-cooled tube, the 8668 is designed for sustained high-power operation. Properly maintained, it can last for decades, with many examples still in service after 30 years. Its robust construction reduces the risk of catastrophic failure under normal operating conditions.

3. **Compatibility with Classic Circuits**

The 8668 is a direct replacement for older high-power tubes like the **4CX1500A** and **4CX2500A**, making it ideal for restoring vintage transmitters. It is also widely used in modern linear amplifiers designed for the 80m 10m bands.

4. **Wide Availability of Parts and Knowledge**

Due to its popularity in amateur radio, spare parts (such as grids, anodes, and water-cooling components) are relatively easy to find. Additionally, there is a wealth of documentation, repair guides, and community support available online.

5. **Efficiency for Linear Amplification**

When paired with a properly tuned circuit, the 8668 can achieve good efficiency (typically **60 75% plate efficiency**), making it cost-effective for high-power transmission. This is particularly useful in amateur radio where efficiency directly impacts operating costs.

6. **Versatility in Applications**

- **Broadcast transmitters** (especially for medium-wave and shortwave).

- **Industrial RF heating and welding applications**.

- **Military and aviation communications systems** (due to its rugged design).

- **Experimental and homebrew projects** where high power is required.

7. **Lower Cost Compared to Modern Alternatives**

While not cheap, the 8668 is often more affordable than newer solid-state amplifiers of equivalent power. For hobbyists and operators running on a budget, it remains a cost-effective solution for high-power RF generation.

8. **Proven Performance in Extreme Conditions**

The tube s water-cooling system allows it to operate reliably even under high ambient temperatures or in environments where forced air cooling would be insufficient. This makes it suitable for field deployments or less-controlled environments.

9. **Modular and Upgradable**

Many 8668-based amplifiers allow for upgrades, such as replacing the water-cooling system with more efficient pumps or adding additional safety features (e.g., over-voltage protection). This extends the tube s lifespan and adaptability.

10. **Cultural and Historical Significance**

For enthusiasts, the 8668 represents a piece of radio history, particularly for those who appreciate vintage technology. Operating a tube like this can be a rewarding experience for those interested in the evolution of radio transmission.

---

### **Cons**

1. **High Initial Cost**

A new 8668 tube can cost **$500 $1,200 USD**, depending on the variant and supplier. Used tubes may be cheaper but come with risks (e.g., unknown history, potential internal damage). Additional costs include water-cooling systems, power supplies, and associated components.

2. **Complex Maintenance and Cooling Requirements**

- **Proper water cooling** (deionized water, correct flow rate, and pressure).

- **Regular cleaning** of the anode and grid to prevent carbon buildup.

- **Monitoring of vacuum levels** (leaks can degrade performance).

- **Careful handling** to avoid damage from static electricity or physical stress.

Failure to maintain these requirements can lead to tube failure or reduced lifespan.

3. **Sensitivity to Operating Conditions**

- **Grid current spikes**, leading to grid erosion.

- **Anode overheating**, risking thermal runaway.

- **Vacuum loss**, which can ruin the tube.

This requires skilled operation and precise tuning, especially for beginners.

4. **Limited Lifespan Under Abuse**

While durable, the 8668 is not indestructible. Poor maintenance, overdriving, or repeated high-power operation can shorten its lifespan significantly. Some operators report tubes lasting **20 30 years** with proper care, while others experience failures within a few years due to neglect.

5. **Space and Power Requirements**

The tube itself is large and heavy (typically **5 7 kg**), requiring dedicated space in a transmitter setup. Additionally, water-cooling systems add bulk and require plumbing, while high-voltage power supplies (often **3 5 kV**) demand careful installation.

6. **Safety Hazards**

- **Electric shock** from high-voltage components.

- **Fire hazards** due to RF arcing or cooling system failures.

- **RF exposure risks** (though properly shielded setups mitigate this).

This necessitates proper grounding, shielding, and safety protocols.

7. **Dependence on Expertise**

- **Understanding of tube characteristics** (plate voltage, grid bias, filament current).

- **Knowledge of RF tuning and matching networks**.

- **Troubleshooting skills** for common issues (e.g., grid current, anode temperature).

Beginners may struggle without guidance from experienced operators.

8. **Environmental and Disposal Challenges**

Tubes contain **lead and other hazardous materials**, making disposal difficult. Recycling options are limited, and improper disposal can be illegal in many regions. This adds an ethical and logistical burden to ownership.

9. **Limited Availability of New Tubes**

- **Longer lead times** for replacements.

- **Higher prices** due to limited supply.

- **Reliance on used market**, which may have inconsistent quality.

10. **Noise and Humidity Sensitivity**

The tube s vacuum can degrade over time due to **outgassing** or **moisture ingress**, especially if not properly baked during initial operation. This can lead to **microphonic noise** or reduced performance. Some operators recommend **baking the tube** (heating under vacuum) to improve reliability.

---

### **Conclusion**

The National 8668/8668-8668/YD1172/YD-1172 is a **powerful, reliable, and efficient** high-power RF triode, but it is **not without significant drawbacks**. It excels in applications where **high power, durability, and historical significance** are priorities, particularly for:

- **Amateur radio operators** running high-power linear amplifiers.

- **Broadcast and industrial users** needing robust RF sources.

- **Enthusiasts** interested in vintage radio technology.

- **Beginners** without experience in tube operation and maintenance.

- **Users seeking plug-and-play convenience** (solid-state amplifiers are easier).

- **Applications with limited space or power resources**.

- **Those unwilling to invest time in maintenance and troubleshooting**.

---

### **Recommendation**

- You are an **experienced amateur radio operator** or engineer comfortable with high-voltage and RF tuning.

- You need **reliable, high-power amplification** for HF bands (especially 80m 10m).

- You appreciate **vintage technology** and are willing to invest in maintenance.

- You have **dedicated space and power** for a water-cooled setup.

- You are restoring or building a **classic transmitter** and need a direct replacement for older tubes.

- You are a **beginner** and lack experience with tube amplifiers.

- You prioritize **ease of use and low maintenance** over performance.

- Your budget is tight, as the **initial cost and long-term maintenance** add up.

- You operate in an environment where **proper cooling and safety measures** are difficult to implement.

- You are considering **modern solid-state alternatives** (e.g., **Amplifier Research 1000D, KPA1500, or homebrew solid-state amps**), which may offer better reliability and convenience for similar power levels.

- **Solid-state amplifiers** (e.g., **KPA1500, Amplifier Research 1000D, or Yaesu

Details:

With a trusted brand like National, this model 8668/YD1172 tube offers reliable performance and quality for vintage electronics enthusiasts. The NATIONAL ELECTRONICS 8668/YD1172/YD-1172 Water-Cooled RF Power Triode Tube is a vintage power tube designed for use in audio and video equipment. Its water-cooled design helps dissipate heat effectively, allowing for consistent operation and durability in demanding audio applications.

part #: yd-1172 price

• $199.00

specifications tubesocketvintagego:

• brand: National
• mpn: 8668
• type: Power Tubes

returns tubesocketvintagego:

• time: 30 Days
• paid by: Buyer
• method: Money back
• policy: Returns Accepted

seller tubesocketvintagego:

• city: Ellington, Connecticut
• rating: 100.0%
• # reviews: 2513

shipping tubesocketvintagego:

• carrier: USPS
• class: Standard
• type: Calculated
• cost: $8.97
• transit: 5-9 Days
• service: USPS Ground Advantage

offer tubesocketvintagego:

• options: Ship-to-home
• started: February 12, 2026
• sold: 0
• availability: In Stock
• best offers: True
• quantity: 1

general tubesocketvintagego:

• Vintage Audio Video > Vintage Parts Accessories > Vintage Tubes Tube Sockets
• condition: Used

payments tubesocketvintagego:

• other
• wallet: Google-pay
• credit card: Discover

National 8668 Is Similar To:

• 0912005 National Union Type Vintage Globe Triode Tube Tests Nos (36.6% similar) 76 through the messaging system. I rate these tubes nos new old stock. I will not guarantee that our readings match your. All our tubes are tested thoroughly on an AT1000. About our tube:all tubes are tested with the audiophile in mind for shorts, gas, mutual conductance and noise large tube lots ...(September 20th, 2018)
• Xe5 Cl-8 188-5 National 10dx8 5 Sylvania Lot Rca Vintage Ge Tube 6f6g (35.1% similar) Vintage 5 tube lot rca XE5 cl 8 National 6F6G sylvan 10DX8 GE tubes have not been tested. There is a rca tube in a National box...(March 5th, 2015)
• 115n030 National Electronics (37.4% similar) Old new in box...(February 9th, 2015)
• 12a5 National Union Vacuum Tube (32.7% similar) Tested with my calibrated TV-7U tube tester. Minimum gm 45 is equal to 65 of the life tube. Tube tested at 79 for shorts and gas. Cut off time for same day shipping is 12 noon pacific. 30 day free return. Up for offer one National 12A5 tube...(February 17th, 2018)
• 12jt6a National Tube Amplifier (23.9% similar) 12JT6A tube's qty...(January 6th, 2015)
• Vintage 12sj7gt Nos Union Vacuum Tube 12sj7 National Nu (14.9% similar) I don't think it has ever been out of the box before now. If we miss your call, please leave a message. Vintage nu National union 12SJ7GT vacuum tube, 12SJ7, nos free shipping. Vintage nu National union 12SJ7GT vacuum tube, 12SJ7 numbers on the tube green box and lettering this item appears to be ...(March 6th, 2015)
• 14w7 Gt National Union Vacuum Tube Nos Nib Single Valvola Hre (25.7% similar) And all the angels sang because heavenly music was playing it turned way up. These tubes are nos nib. It is easy at that point to take where top line intersects the plate voltage , find lamp level and compare data sheet. All are nos nib and tested by me. I give a number of evaluations for tubes. At...(January 16th, 2019)
• 159w5c194ghct National Electronics New Crt (41.3% similar) This National electronics 159W5C194GHCT CRT tube is new in box...(June 26th, 2017)
• 182-b National Union Vintage Triode Nos (37.3% similar) Tested OK on TV10D u as a type 45 with proper filament voltage . Original box included, but is in poor condition. 182-B vintage triode nos National union...(March 8th, 2019)
• 190fb4 National Electronics Cathode Ray (45.8% similar) A note on bids and traveling. Buyer pays return shipping. This is especially useful should you find when return that are the winning bidder. Shipping calculator is at the bottom of this offer to calculate charges lower 48 states. Please see note on bids and traveling below.: National electronics ...(April 14th, 2017)
• 6x5gt Vintage Union National Nos Test Tube Pair Nib 1940-1945 Great. (25.5% similar) Next day shipping we combine shipping. Everything always arrives fast and fine. Canada everything always arrives fast and fine USA shipping rest of world typically 9 to test great for rectifier tubes tube tube vintage about 1945TWO solid rectifiers also tested no shorts. National union 6X5GT tube ...(February 11th, 2015)