RCA 1645A Cell Tubes

( Brand: Rca ), ( Manufacturer Part Number: 1645A ), ( Type: Vacuum Tube ), ( Country Of Origin: United States )

Review RCA Photo Cell Tubes Untested Pair

The RCA 1645A Cell Tubes are a classic and highly sought-after component in the world of vintage electronics restoration, ham radio, and audio enthusiast projects, particularly for those working with early transistor radios, tube amplifiers, and other analog circuitry from the mid-20th century. These small, cylindrical glass tubes belong to the family of **germanium point-contact transistors**, specifically designed as **PNP (Positive-Negative-Positive) devices**, and were originally manufactured by RCA (Radio Corporation of America) in the late 1950s and early 1960s. The 1645A is a direct descendant of the earlier 1645 model, with subtle improvements in performance and reliability, making it a dependable choice for applications requiring low-power amplification, switching, or signal processing in portable or battery-operated devices. Unlike modern silicon transistors, which are robust and heat-tolerant, the 1645A operates within a delicate range of voltages and currents, typically handling up to **100 mA of collector current** and **150 mV of reverse breakdown voltage**, while maintaining a **gain (hFE) of around 20 to 100**, depending on the individual unit. Its compact, **TO-5 metal can package** (though some variants may feature a plastic or glass encapsulation) houses the germanium junction, which is highly sensitive to temperature fluctuations requiring careful handling to avoid thermal damage or performance degradation. The 1645A s unique characteristics, such as its **low noise figure** and **fast switching speed** for its era, made it a favorite in early transistor radios like the RCA TRK-1 and TRK-2, where it served as the primary amplification stage for the audio signal. For collectors and restorers, these tubes are prized not only for their historical significance but also for their distinct **hissing sound** when active, a trait that adds to the nostalgic charm of vintage electronics. However, their fragility and sensitivity to static electricity, heat, and improper polarity make them challenging to work with, necessitating patience and precision when soldering or replacing them in circuits. Today, the 1645A remains a coveted part among hobbyists, often sourced from eBay, vintage electronics swap meets, or specialized transistor distributors, where they command a premium due to their scarcity and the difficulty in sourcing exact replacements. Whether used in a restored transistor radio, a DIY amplifier project, or as a curiosity piece in a collection, the RCA 1645A Cell Tubes embody the ingenuity of early semiconductor technology and continue to fascinate those who appreciate the art of analog electronics.

### Pros and Cons of Buying RCA 1645A Cell Tubes

The RCA 1645A is a classic, high-quality vacuum tube known for its performance in audio applications, particularly in preamplifiers, power amplifiers, and guitar amplifiers. Here are its key advantages:

1. **Superior Sound Quality** The 1645A is widely regarded for its smooth, detailed, and dynamic sound, making it a favorite among audiophiles and musicians seeking warm, natural tone. It is often praised for its ability to handle both low and high frequencies with clarity and warmth.

- **Preamplifiers** (e.g., in solid-state or tube preamps for guitar or audio)

- **Power amplifiers** (both single-ended and push-pull configurations)

- **Guitar amplifiers** (notably in models like the Fender Twin Reverb and Marshall JMP-1)

- **Phono stages** (for vinyl playback, where its low noise and smooth response are beneficial)

3. **Durability and Longevity** When properly cared for, the 1645A can last for thousands of hours, though like all tubes, it degrades over time. Its construction is robust, and it is less prone to catastrophic failure compared to some modern alternatives.

4. **Warmth and Harmonic Richness** The tube excels at adding subtle harmonic distortion that many musicians and audiophiles find desirable. It is particularly well-suited for genres like blues, jazz, and vintage rock, where a "tube sound" is sought after.

5. **Compatibility with Vintage Gear** Since the 1960s, the 1645A has been a staple in many classic amplifiers and preamps. Buying new or used tubes ensures compatibility with a wide range of vintage equipment without the need for modifications.

6. **Low Noise Characteristics** Compared to some other tubes, the 1645A has relatively low noise output, making it suitable for clean amplification and sensitive preamp stages.

7. **Availability of Replacements** While not as common as some other tubes (like the 12AX7), the 1645A is still produced by several manufacturers (e.g., RCA, JJ Electronics, Sovtek, and others), ensuring a steady supply of replacements.

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1. **High Cost** Compared to more common tubes like the 12AX7 or 12AT7, the 1645A is relatively expensive. Prices for new tubes can range from $20 to $50 or more, depending on the manufacturer and region. Used tubes may be cheaper but riskier due to unknown history.

2. **Limited Availability of Some Brands** While several manufacturers produce 1645A-compatible tubes, not all brands are equally reputable. Some budget options may sacrifice performance for cost, leading to inconsistent sound or shorter lifespans.

3. **Sensitivity to Power Supply Variations** The 1645A can be finicky with power supply conditions. Poorly regulated or noisy power can lead to inconsistent performance, including hum, distortion, or premature failure. This requires careful attention to circuit design and power supply quality.

4. **Heat Sensitivity** Like all tubes, the 1645A generates heat, and excessive heat can reduce its lifespan or cause performance degradation. Proper heatsink design and ventilation are essential in amplifier circuits.

5. **Not Ideal for High-Gain Applications** While the 1645A works well in moderate-gain scenarios, it is not as robust as some other tubes (e.g., the EL34 or 6L6) for high-gain or high-power applications. It may break up or distort unpredictably in such contexts.

6. **Replacement Complexity** Some vintage amplifiers or custom builds may require modifications to accommodate the 1645A s pinout or voltage requirements. This can be a barrier for DIYers without experience in tube electronics.

7. **Environmental Sensitivity** Tubes are sensitive to humidity, dust, and electrical interference. Storing them improperly or operating them in harsh conditions can lead to premature failure or degraded performance.

8. **Learning Curve for New Users** For those unfamiliar with tube electronics, the 1645A requires an understanding of proper handling, replacement, and maintenance. Mishandling (e.g., touching the filament or exposing it to power without proper warm-up) can damage the tube.

---

The RCA 1645A is a **premium tube** with a well-deserved reputation for its exceptional sound quality, versatility, and durability. It is an excellent choice for audiophiles, vintage gear enthusiasts, and musicians who prioritize warmth, clarity, and harmonic richness in their amplification. However, its higher cost, sensitivity to power supply conditions, and niche applications may not make it the best fit for everyone.

If you are building or restoring a **vintage amplifier, preamp, or phono stage**, or if you are a musician seeking a **classic tube sound for guitar or audio applications**, the 1645A is a strong recommendation. For high-gain or high-power applications, or for those on a tight budget, alternatives like the **EL34, 6L6, or 12AX7** may be more practical.

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- You are working with **vintage gear** (e.g., Fender Twin Reverb, Marshall JMP-1, or custom tube preamps).

- You prioritize **warmth, detail, and natural harmonic distortion** in audio or guitar amplification.

- You have a **stable power supply** and proper heatsink design in your circuit.

- You are willing to invest in **high-quality tubes** for long-term reliability.

- You need a **budget-friendly option** (e.g., EL34 for power amps or 12AX7 for preamps).

- Your application requires **high gain or high power** (e.g., modern guitar amps).

- You are new to tubes and need **more forgiving or widely available options**.

For best results, purchase from **reputable manufacturers** (e.g., RCA, JJ Electronics, or Sovtek) and ensure proper handling and storage. If restoring vintage equipment, verify compatibility with your specific circuit before purchasing.

Details:

Up for sale is a pair of RCA 1645A photo cell tubes which are untested. Shipping and handling charges: cost is calculated by your zip code but there are no extra charges for packing materials or my labor.

part #: 1645a price

• $30.00

specifications tubesocketvintagego:

• brand: Rca
• mpn: 1645a
• type: Vacuum Tube
• country of origin: United States

shipping tubesocketvintagego:

• class: Standard
• cost: $6.07
• carrier: USPS
• type: Calculated
• service: USPS Ground Advantage
• transit: 4-8 Days

payments tubesocketvintagego:

• credit card: Visa
• wallet: Paypal
• other

seller tubesocketvintagego:

• city: Titusville, Florida
• rating: 100.0%
• # reviews: 11111

returns tubesocketvintagego:

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

offer tubesocketvintagego:

• sold: 0
• quantity: 1
• options: Ship-to-home
• availability: In Stock
• started: May 14, 2026
• best offers: True

general tubesocketvintagego:

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

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