MOTOROLA B93RCB-3105 Bones Hf Amplifier Ceramic Tubes 500 8560

( Brand: Motorola ), ( Manufacturer Part Number: B93RCB-3105 ), ( Type: Linear Amplifier ), ( Band: Hf )

Review MOTOROLA Bones 500 Watt Hf Amplifier Project Ceramic Tubes

The **Motorola B93RCB-3105 Bones** are a meticulously crafted, high-performance set of **ceramic tube sockets** designed exclusively for the **Motorola 500HF amplifier**, a legendary piece of audio equipment renowned for its robust construction and exceptional sound quality. These sockets are engineered to provide a secure, low-resistance connection between the amplifier s **8560 ceramic tubes** and their respective circuit boards, ensuring optimal signal integrity and longevity of the tubes themselves. Crafted from premium **ceramic material**, the B93RCB-3105 Bones are built to withstand the thermal and electrical demands of high-power audio amplification while maintaining precise alignment and mechanical stability. Their **precision-machined pins** guarantee a consistent, vibration-free fit, reducing the risk of loose connections that could introduce noise or signal degradation. Ideal for both audiophiles seeking to restore or upgrade their 500HF amplifier and technicians performing routine maintenance, these sockets are a testament to Motorola s engineering excellence, offering a reliable solution for those who demand nothing less than perfection in their audio systems. Whether used in a studio, home theater, or live sound environment, the B93RCB-3105 Bones ensure that the full potential of the 8560 tubes is realized, delivering clean, powerful, and dynamic sound with every note.

Buying a used Motorola B93RCB-3105 amplifier with 8560 ceramic tubes for around $500 is a decision that depends on your needs, budget, and technical expertise. Below is a detailed breakdown of the pros and cons, followed by a conclusion and recommendation.

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### **Pros of Buying This Amplifier**

1. **High Power Output**

The B93RCB-3105 is a robust linear amplifier designed for professional use, capable of delivering significant power (typically around 1.5 kW to 2 kW PEP with 8560 tubes). This makes it suitable for high-power broadcasting, studio monitoring, or serious amateur radio applications.

2. **Reliable Tube Technology**

8560 ceramic tubes are known for their durability and consistent performance, especially in high-power applications. Ceramic construction is less prone to thermal shock compared to glass tubes, making them more reliable in demanding environments.

3. **Professional-Grade Build**

Motorola amplifiers like this one are built with industrial-grade components, including robust transformers, high-quality capacitors, and sturdy chassis construction. This ensures longevity if maintained properly.

4. **Compatibility with Broadcast and Amateur Radio**

If you're involved in broadcasting (e.g., FM, SWL, or amateur radio), this amplifier can serve as a reliable final stage. It s often used in field-day operations or as a backup transmitter.

5. **Resale Value and Collectibility**

Motorola amplifiers from this era (1970s 1980s) are sought after by collectors and professionals. If you decide to upgrade later, you may still find buyers willing to pay a decent amount for it.

6. **Adjustability and Tuning**

The B93RCB-3105 allows for fine-tuning of plate voltage, screen voltage, and other parameters, which can optimize performance for specific applications (e.g., SSB vs. CW).

7. **Lower Cost Relative to New Alternatives**

At $500, this amplifier is significantly cheaper than a new high-power linear amplifier (which can cost several thousand dollars). For the price, you re getting a well-built, high-power tube amp that could last decades with proper care.

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### **Cons of Buying This Amplifier**

1. **Age and Wear**

The B93RCB-3105 is likely decades old, which means some components (e.g., capacitors, resistors, wiring) may be degraded or failing. Without a thorough inspection, you risk inheriting hidden issues like shorted capacitors or worn-out insulators.

2. **Maintenance Requirements**

- **Tube replacements** (8560s can last 10,000 20,000 hours but degrade over time).

- **Capacitor replacements** (electrolytic capacitors dry out and fail; ceramic caps may also degrade).

- **Insulation checks** (dirt, oil, or moisture can cause arcing).

- **Transformer inspections** (high-voltage windings can degrade over time).

If you re not experienced with tube amps, this could become a costly hassle.

3. **Power Supply and Safety Concerns**

High-power tube amps like this one draw significant current and operate at high voltages. If the power supply or grounding is faulty, it poses a serious risk of fire or electrical shock. You ll need to verify the safety of the unit before use.

4. **Limited Modern Compatibility**

The B93RCB-3105 may not have built-in features like digital tuning, USB interfaces, or modern safety circuits. If you re used to plug-and-play amplifiers, this one will require manual adjustments and troubleshooting.

5. **Noise and Harmonics**

Older tube amplifiers can produce more noise and harmonics compared to modern solid-state or digitally controlled amps. If you re sensitive to audio purity (e.g., for studio work), this may not be ideal.

6. **Weight and Portability**

This is a heavy, bulky unit (likely 50 100 lbs). Moving it requires careful handling, and it s not designed for portable use like some modern amplifiers.

7. **Depreciation Risk**

While tube amps can hold value, they also depreciate over time. If you re not planning to use it long-term or resell it later, the initial cost may not be fully justified.

8. **Learning Curve**

Operating and maintaining a high-power tube amp requires knowledge of RF safety, tube characteristics, and amplifier tuning. Beginners may struggle with diagnostics and repairs.

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### **Conclusion**

- You have experience with tube amplifiers or are willing to learn.

- You need a high-power amplifier for broadcasting, amateur radio, or studio use where cost is a priority over convenience.

- You plan to maintain it properly and are prepared for potential repairs.

- You value the reliability and professional-grade build of a vintage amplifier.

- You re a beginner with no experience in tube amp maintenance.

- You prioritize modern features like digital controls, ease of use, or low noise.

- You re on a tight budget and cannot afford unexpected repair costs.

- You need a portable or plug-and-play solution.

---

### **Recommendation**

1. **Inspect Thoroughly Before Purchase**

- Check for signs of arcing, burnt components, or swollen capacitors.

- Verify that all tubes (8560s) are in good condition (no cracks, blackened grids).

- Test the amplifier under load (if possible) to ensure it s functioning correctly.

- Ask the seller for maintenance records or proof of recent servicing.

2. **Budget for Maintenance**

Allocate an additional **$200 $500** for potential repairs (e.g., capacitor replacements, tube upgrades, or transformer checks). This is a necessary part of owning a used tube amp.

3. **Consider Alternatives**

- If you re new to tube amps, start with a **used but well-documented** lower-power amplifier (e.g., a 4-125 or 4CX250B-based amp) to learn the basics.

- If you need a modern solution, look into **solid-state amplifiers** (e.g., Yaesu FT-1000MP, Icom IC-7800 with external amp) or **digital linear amps** (e.g., Elecraft K3 with external amp).

- If you re serious about broadcasting, a **new or lightly used** high-power amp (e.g., a modern Motorola or Collins-based unit) might be worth the higher cost for reliability.

4. **Proceed with Caution**

If you decide to buy it, treat it as a **long-term investment** rather than a quick purchase. Join tube amp forums (e.g., TubeAmps.com, ARRL forums) for guidance on maintenance and troubleshooting.

**Final Verdict**: The B93RCB-3105 is a **strong choice for experienced users** who need a high-power, durable amplifier and are prepared for its maintenance demands. For beginners or those seeking convenience, it may not be the best fit. Always prioritize inspection and budget for upkeep.

Details:

This came from a working Motorola vhf 500 watt repeater. Comes with 4 tubes all are in good to great condition. The 8560 has same ratings as 4CX250. See pictures for all paper work that comes with it.

Any questions. The Motorola heat sink keep every thing nice and cool. Selling cage and tubes only. I rebuilt this to operate as a 7 MHz AM running class AB1 had 250 watts out with only 30 drive.

part #: b93rcb3105 prices

• $57.24-$247.97

specifications hamamateuradio:

• brand: Motorola
• mpn: B93rcb-3105
• type: Linear Amplifier
• band: Hf

general hamamateuradio:

• condition: For parts or not working
• Radio Communication > Ham, Amateur Radio > Ham Radio Amplifiers

seller hamamateuradio:

• # reviews: 403
• city: Nashville, Michigan
• rating: 100.0%

shipping hamamateuradio:

• transit: 3-8 Days
• service: FedEx Ground / FedEx Home Delivery
• cost: $44.13
• carrier: FedEx
• type: Calculated
• class: Standard

offer hamamateuradio:

• started: February 4, 2026
• best offers: True
• availability: In Stock
• quantity: 1
• sold: 0
• options: Ship-to-home

payments hamamateuradio:

• other
• credit card: Diners-club
• wallet: Paypal

returns hamamateuradio:

• policy: No Returns

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