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NATIONAL UNION

5Z3 VT-145 NATIONAL UNION NOS NIB Matched Pair Hanging Filaments Black Plates Foil Getter USA

5Z3 VT-145 NATIONAL UNION NOS NIB Matched Pair Hanging Filaments Black Plates Foil Getter USA

€159,80 EUR
€159,80 EUR
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5Z3 ( VT-145 ) NU NOS NIB Black Plates Hanging Filaments Foil Getter Engraved Base Tube Rectifiers Made in USA

Description:

The National Union 5Z3 (VT-145) , made in the USA in the 1940s, are double half-wave rectifiers equivalent to the 5U4G, widely used in military radios, transmitters, and early audio power amplifiers.
These examples are in NOS NIB (New Old Stock – New in Box) condition and offer fine construction details such as the black plates , hanging filaments , foil getter and engraved base , distinctive features of National Union production of the time.

Tubes of this level not only represent a piece of American thermionic technology history, but are also highly appreciated for their refined and reliable sound reproduction.

Timbral characteristics and sound behavior

Bass: Full and deep, with excellent control. It provides a stable and authoritative foundation that gives solidity to the entire range.

Mids: Transparent, rich, and musical. Voices and acoustic instruments emerge with realism and naturalness.

Highs: extended and fluid, with a balanced, never fatiguing brilliance. They offer airiness and detail without harshness.

Dynamics: prompt and incisive, with the ability to follow both rapid transients and complex passages.

Soundstage: wide and three-dimensional, with clear separation of instruments and excellent depth.

🎧 Use in Hi-Fi amplifiers

Perfect for vintage tube power amplifiers and hi-fi preamplifiers, where they ensure stable power supply and an elegant, refined sonic impact.

🎸 Use in musical instrument amplifiers

Ideal for historic organs and amplifiers, they provide reliable power and a rich, robust, musical sound with a warm, authentic character.

🎯 Note for audiophiles and technicians

The 5Z3 (VT-145) National Union Black Plates with suspended filaments, foil getter and engraved base represent some of the most fascinating and sought-after versions of this historic grinder.
A perfect option for those looking for technical reliability, musicality and collectible value , suitable for both philological restorations and high-end hi-fi systems.

Test Results:

Tubes tested on Funke W19 Tube tester:
Voltage Test: Va = 100V, Vf = 5V
Good from: Ia = 78 mA
Average 100% Ia = 120 mA
Test Result: VERY STRONG

Plate current

Valve 1:

  • Section 1: Ia = 102 mA
  • Section 2: Ia = 102 mA

Valve 2:

  • Section 1: Ia = 105 mA
  • Section 2: Ia = 110 mA

Plate current:

Additional Tests

  • Operation: Stable tube, silent in operation and suitable for providing a regular and well-controlled power supply. Tested with Funke W19 tube tester.
  • Output Quality: Excellent – Very strong and stable output, no fluctuations.
  • Short circuits and GAS: Absent.

Conditions:

  • Conditions: NOS - NIB - New Old Stock, New In Box - Tested and working - Supplied in original box.
  • Functionality: Fully functional.
  • Cosmetic condition: Excellent – Excellently preserved lettering, minimal signs of wear. See photos for details.
  • Manufacturing Code: Absent - Year of manufacture obtained from the internal structure - Manufactured in the 1940s

Find out why our valves are different →

Terms of Sale & Safety

Sales Terms & Product Safety

Each vacuum tube is carefully selected, tested, and verified in our laboratory before shipment. Where stated in the listing, test results, matching data, and declared characteristics refer to measurements performed using the specified test equipment and operating conditions.

Sound descriptions are provided for guidance only and reflect the characteristics generally associated with that particular tube type. Personal sound preferences, tube rolling, or perceived differences between audio systems do not constitute a product defect.

Before installation, please verify the tube’s electrical and mechanical compatibility with your equipment and follow the manufacturer’s instructions.

New production and NOS tubes are shipped with a tamper-evident security seal and internal technical documentation to ensure traceability of the product’s condition at the time of shipment.

Product Safety (GPSR)

Vacuum tubes are electronic components intended exclusively for use in compatible equipment and must be installed in accordance with the equipment manufacturer’s instructions.

Due to their historical or vintage nature, certain technical specifications may be based on original datasheets or equivalent technical documentation when documentation from the specific manufacturer is unavailable.

Use only with suitable equipment. Keep out of reach of children.

Shipping & Returns

Shipping & Returns

We ship worldwide using carefully selected express carriers and protective packaging specifically designed for vacuum tubes.

If you change your mind, you may exercise your right of withdrawal within 14 days of delivery, where applicable under the relevant consumer protection laws. The product must be returned complete with its original packaging and accessories, in the same commercial condition in which it was received. Return shipping costs are the responsibility of the customer.

Every returned item undergoes a technical inspection. Installation, use, tube rolling, or any other handling may reduce the product’s commercial value and may affect the refund amount, in accordance with applicable law.

If you believe the product has a lack of conformity, our laboratory will carry out the necessary inspections and apply the remedies provided by the applicable consumer protection legislation.

For further details, Customers are invited to consult the “Terms and Conditions” and “Refund Policy” sections of our website, or to contact us before placing an order.

Vacuum Tubes Treasures
www.vtt.store | www.vacuumtubestreasures.com
📧 info@vacuumtubestreasures.com

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  • ATTENTION PLEASE

    Please understand that the writing on the glass of vintage valves has become very delicate over the years and comes off easily. You must handle them with extreme care to avoid this. Wear and damage to the writing on the valves reduces their market value and causes damage. Please exercise extreme caution.

  • ATTENTION PLEASE

    We wish to inform you that any attempts to manipulate shipping destination information in order to obtain lower shipping rates may be considered fraudulent acts. Please provide accurate information and contact us if you have any concerns. We reserve the right to review and, if necessary, cancel orders that we deem to be in violation of our conditions. Thank you for your understanding and cooperation.