JENNINGS Vacuum Capacitors CADC-30-7.5N779 1-NOS 1-PULLED

( Brand: Jennings ), ( Manufacturer Part Number: CADC-30-7 ), ( Model: JENNINGS CADC-30-7 .5 N779 ), ( Type: Vacuum Variable Capacitor ), ( Country Of Origin: United States )

Review JENNINGS Pair Vacuum Variable Capacitors 1-pulled

The **Jennings CADC-30-7 (CADC-30-7.5N779) Vacuum Capacitor**, a single-unit, pulled specimen in pristine condition, represents a rare and highly sought-after component in the realm of high-voltage and high-power electronics. This meticulously engineered vacuum capacitor is designed to deliver exceptional performance in demanding applications where reliability, longevity, and superior dielectric strength are paramount. Manufactured by Jennings, a trusted name in precision capacitors, this unit belongs to the CADC series, renowned for its robust construction and ability to handle extreme electrical stresses without degradation. The CADC-30-7 designation indicates a nominal capacitance rating of 30 picofarads (pF), though actual measured values may vary slightly due to the nature of vacuum capacitors, which rely on the physical separation of electrodes rather than a dielectric material. The "7" suffix suggests a specific voltage rating or internal configuration tailored for high-voltage environments, while the "7.5N779" likely denotes a unique serial or model variant, adding to its exclusivity as a pulled, one-of-a-kind specimen.

Physically, the Jennings CADC-30-7 is constructed with an emphasis on durability and precision. The capacitor is housed in a robust, hermetically sealed metal enclosure, typically made from high-grade steel or aluminum, designed to withstand mechanical stress, thermal fluctuations, and corrosive environments. The internal structure features two parallel electrodes suspended within a vacuum-sealed chamber, eliminating the risk of dielectric breakdown or leakage currents that plague traditional electrolytic or ceramic capacitors. This vacuum environment ensures an exceptionally long operational lifespan, often measured in decades, as there are no degrading materials to fail over time. The terminals are meticulously crafted for low-inductance connections, allowing for efficient energy transfer in high-frequency applications, such as pulse generators, radar systems, or high-voltage switching circuits.

One of the most compelling attributes of the Jennings CADC-30-7 is its suitability for applications requiring ultra-low loss and high Q-factor performance. Vacuum capacitors inherently exhibit negligible dielectric loss, making them ideal for resonant circuits, oscillators, and filters where energy efficiency is critical. The absence of a dielectric material also means that the capacitance remains stable across a wide range of temperatures and frequencies, a feature that is particularly valuable in aerospace, defense, and industrial automation systems. Additionally, the vacuum-sealed design provides inherent protection against environmental contaminants, humidity, and mechanical shock, further enhancing its reliability in harsh operating conditions.

For collectors, engineers, and enthusiasts of vintage electronics, the CADC-30-7 (7.5N779) holds significant appeal as a pulled, one-of-a-kind unit. Being a "pulled" capacitor means it was removed from inventory or production for reasons such as testing, demonstration, or obsolescence, making it a rare find that often commands a premium in the secondary market. Its historical and technical value lies in its association with legacy systems, where Jennings capacitors were a staple in early radar, military communications, and high-voltage research. The inclusion of the specific serial number "7.5N779" adds an extra layer of authenticity and traceability, allowing owners to verify its provenance and ensure it meets the exact specifications of original equipment manufacturers (OEMs) that may still rely on such components for critical repairs or retrofits.

In summary, the **Jennings CADC-30-7 (CADC-30-7.5N779) vacuum capacitor** is a testament to engineering excellence, offering unparalleled performance, longevity, and reliability in the most demanding electrical applications. Whether used in modern restoration projects, high-precision instrumentation, or as a prized addition to a collector s archive, this vacuum capacitor embodies the pinnacle of analog electronics design a self-contained, maintenance-free solution that continues to deliver exceptional service decades after its manufacture. Its unique status as a pulled specimen further elevates its desirability, making it a coveted component for those who demand nothing less than the finest in electrical engineering heritage.

**Pros and Cons of Buying Jennings CADC-30-7 (CADC-30-7.5N779) Vacuum Capacitors (1NOS, 1 Pulled)**

1. **High Quality and Reliability** Jennings is a well-respected brand in the vacuum tube and capacitor industry, known for durable and high-performance components. These capacitors are designed for precision audio and RF applications, where stability and low loss are critical.

2. **Low Inductance and Loss** Vacuum capacitors inherently have very low dielectric absorption and inductance, making them ideal for high-frequency and sensitive circuits (e.g., preamplifiers, tube amps, RF stages). This minimizes signal distortion and phase shift.

3. **Long Lifespan** Unlike electrolytic or film capacitors, vacuum capacitors do not degrade over time due to leakage or polarization issues. They are virtually maintenance-free and can last decades if properly applied.

4. **Precision Tolerances** These capacitors are often used in custom tube amplifier builds where exact capacitance values are required for optimal performance. The CADC-30 series is known for tight tolerances, ensuring consistent results.

5. **Compatibility with High-Voltage Applications** Jennings vacuum capacitors are rated for high-voltage use (e.g., 300V or higher), making them suitable for power amplifier stages where robust insulation is necessary.

6. **Minimal Temperature Coefficient** Unlike ceramic or film capacitors, vacuum capacitors exhibit negligible capacitance drift with temperature changes, which is beneficial in environments with varying thermal conditions.

7. **No Aging or Leakage** Unlike electrolytic capacitors, they do not suffer from dry-out or leakage currents, which can be a major issue in long-term storage or high-reliability applications.

8. **Used in Professional and High-End Audio** Many audiophiles and professional tube amplifier builders prefer Jennings capacitors for their superior sound quality and reliability. This can add value if reselling or trading in the future.

---

1. **High Cost** Vacuum capacitors, especially from reputable brands like Jennings, are significantly more expensive than standard film or electrolytic capacitors. The price per unit can be prohibitive for budget-conscious projects.

2. **Limited Availability** New stock of Jennings capacitors can be difficult to find, especially for specific part numbers like the CADC-30-7. The "1NOS" (one of a kind) and "1 pulled" (likely defective or damaged) designation suggests this is a used or salvage item, which may further limit availability.

3. **"Pulled" Condition** The term "pulled" typically means the capacitor was removed from service due to failure or damage. While some pulled capacitors can be refurbished and restored to working order, others may have internal defects (e.g., cracked plates, degraded insulation, or shorted elements) that make them unusable. Testing is essential before purchase.

4. **Testing Required** Even if the capacitor appears physically intact, vacuum capacitors must be tested for capacitance, leakage, and insulation resistance. Without proper testing equipment (e.g., a capacitance bridge, megohmmeter, or oscilloscope), there s a risk of purchasing a faulty unit.

5. **No Warranty or Guarantee** Since this is a used or salvage item, there is no return policy or warranty. If the capacitor fails after purchase, there is no recourse.

6. **Specialized Knowledge Needed** Working with vacuum capacitors requires understanding of high-voltage handling, proper soldering techniques (to avoid damaging the vacuum seal), and circuit integration. Improper handling can lead to catastrophic failure.

7. **Potential for Counterfeit or Mismarked Parts** The used market can have counterfeit or mislabeled capacitors. Without verification from a trusted seller (e.g., a reputable tube parts dealer or auction house), there s a risk of receiving a fake or incorrect part.

8. **Limited Use Cases** While excellent for audio and RF applications, vacuum capacitors are overkill for general-purpose circuits where cheaper alternatives (e.g., film or ceramic capacitors) would suffice. This makes them less versatile for non-audio projects.

---

- You are a **tube amplifier builder or audio enthusiast** who prioritizes performance and longevity.

- You have **access to testing equipment** to verify the capacitor s functionality before installation.

- You are **willing to pay a premium** for high-quality, low-loss components.

- The capacitor is **authentic and in good condition** (not counterfeit or damaged beyond repair).

However, the risks particularly the uncertainty of the "pulled" condition, lack of warranty, and high cost make this purchase **less ideal for casual users, hobbyists on a budget, or those without experience in vacuum capacitor handling**. If you proceed, **thorough testing and verification from a trusted source are non-negotiable**.

---

- **Purchase from a reputable seller** (e.g., a well-reviewed tube parts dealer or auction house like eBay with verified feedback).

- **Request full testing reports** (capacitance, leakage, insulation resistance) before buying.

- **Consider buying new if possible** some Jennings capacitors are still available in stock from authorized distributors.

- **Budget for a spare** since vacuum capacitors are irreplaceable in some circuits, having a backup is wise.

- **Avoid the "pulled" unit** unless you are confident in your ability to test and refurbish it.

- **Explore alternatives** like high-quality film capacitors (e.g., Sprague, Cornell Dubilier) or used but tested Jennings capacitors from trusted sources.

- **Start with a smaller project** to test your comfort level with vacuum components before committing to high-value parts.

- **Gain experience with cheaper, non-critical vacuum capacitors** (e.g., smaller values or less expensive brands) before investing in a high-end Jennings unit.

- **Learn proper testing methods** (e.g., using a capacitance meter and megohmmeter) to avoid wasting money on faulty parts.

**Final Verdict:** The Jennings CADC-30-7 is a **premium component** with clear advantages for the right user, but the "pulled" condition and lack of guarantees introduce significant risk. **Only proceed if you are prepared to verify its condition and understand the implications of using a used component in a critical circuit.** For most casual users, a new or well-tested alternative may be a safer and more cost-effective choice.

Details:

No dents, cracks, or obvious damage. RF matching networks. Both look nearly identical, with clean ceramic bodies, smooth tuning shafts, and intact blue insulators. These are high-quality vacuum variables ideal for: Broadcast / amateur radio transmitters and antenna tuners.

voltage : 7.5 JV peak. They appear to be in great shape and should perform well, but please verify upon receipt for your application. Industrial RF heating and plasma equipment. High- voltage , high-power circuits where low loss and reliability matter.

Note: Untested by me no capacitance meter or high- voltage tester available. Current: 15 20 A RMS excellent for RF applications. Up for sale is a matched pair of genuine Jennings ITT Jennings CADC-30-7.5N779 ceramic vacuum variable capacitors. Specs: Capacitance: 3 30 pf variable.

Vacuum capacitors are robust but can lose performance if the seal is compromised. Condition: One unit: New Old Stock NOS never installed, pristine with full original markings.

part #: cadc307 price

• $99.00

specifications tubesocketvintagego:

• brand: Jennings
• mpn: Cadc-30-7
• model: Jennings Cadc-30-7 .5 N779
• type: Vacuum Variable Capacitor
• country of origin: United States

seller tubesocketvintagego:

• rating: 98.8%
• # reviews: 282
• city: Tucson, Arizona

general tubesocketvintagego:

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

returns tubesocketvintagego:

• policy: No Returns

shipping tubesocketvintagego:

• type: Calculated
• service: UPS Ground
• transit: 4-8 Days
• carrier: UPS
• class: Standard
• cost: $9.06

offer tubesocketvintagego:

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

payments tubesocketvintagego:

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

Jennings CADC-30-7 Is Similar To:

• R1d-26n300 Jennings Itt Radio Vacuum Relay Tube Vdc Ohms (35% similar) See pictures for details. Please only bid if you agree with the guarantee. Tubes are used but were taken from a working environment. This is my guarantee on vintage electronics. See my other offers for more vintage audio gear. The tube is 265 ohms and 26. Please see below for details on shipping. Up...(September 13th, 2018)
• Rf1d26s Jennings New Volt Vacuum Relay (33.6% similar) New Jennings volt RF1D 26S vacuum relay, P/N RF1D26S...(August 29th, 2018)
• Rig4253a22a10 Jennings Vacuum Relay Tube (31.4% similar) This includes poor print, oxidized pins, faint discoloration, or some grime. The testing is done on vintage tube testers. Buying and offers - all questions, conditions, constraints shall be made prior to making an offer or purchase, any after placement of the order are null void. You get the tube ...(November 26th, 2017)
• Tc-25 Jennings Radio Variable Vacuum Tube Capacitor Cvv Glass Pf (45.5% similar) I'm not really familiar with these, but my research shows that it is a vacuum variable capacitor made by Jennings, model CV TC-25-20S, rated 4 to 25 pf at 20KV. Since the metal parts show wear I'm guessing it is used, but glass and interior are nice clean. It is 2 in diameter, 75 long, 5/8 hub front...(May 3rd, 2018)
• Vc-12 20kv 12-20 Jennings Pair Radio Vacuum Capacitor Tube (51.8% similar) I pack and ship to you, the way would want you me. I strive to ensure your entire buying experience rates 5 stars. Please visit my other offers. Please see to photos for condition and quality...(May 18th, 2018)
• W-100 Jennings Nib Usa Vacuum (34.5% similar) Tube type number: W-100 actual brand: Jennings printed brand: quantity: 1 piece-single matching date codes. Plate construction: fetter country of manufacture: USA visible codes: lettering condition: 100% number mica spacers: spacer shape: saw rectangle glass coating: clear engraved base. No boxes ...(March 29th, 2017)
• Vc50 Jennings Radio Vacuum Capacitor (49.6% similar) Shipped with USPS first class package. Jennings VC50 vacuum capacitor 50PF 32KV...(January 14th, 2020)
• Jennings 1200-40n761 Water Cooled Variable Capacitor Cvfw 40kv Voa Radio Pull (53.2% similar) Jennings water cooled variable capacitor VFW 1200-40N761 40KV VOA radio pull. And data specs included as screenshots only no papers, look over all the pictures...(February 6th, 2026)
• Jennings Ucsx-1000-15s Itt Variable Vacuum Capacitor 1000 Pf 15 Kv Peak (50.6% similar) With its brand name reputation and quality construction, this capacitor is a sought-after piece for collectors enthusiasts of vintage electronics. The tit Jennings UCSX-1000-15S variable vacuum capacitor is a vintage electronic component made in the USA. From the collection of a lifetime radio ...(May 31st, 2026)