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NATIONAL UNION

6V6GT National Union Matched Pair Smoked Glass Black Plates Foil Getter Made in USA '50s

6V6GT National Union Matched Pair Smoked Glass Black Plates Foil Getter Made in USA '50s

₩205,000 KRW
₩205,000 KRW
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6V6GT NU (National Union) – Smoked Glass – Black Plates – Foil Getter – Matched Pair – Made in USA ‘50s

VACUUM TUBES TREASURES Selection – Low Noise & Microphonics

One tube has a crack on the plastic base, visible in the photo.

This is an exclusively cosmetic defect that does not affect performance, as verified during testing.

Test Results:

Tube tested on AMPLITREX AT-1000 Tube Tester:

  • Test Conditions: Va = 250V; Vg2 = 250V; Vg = -12.5V 
  • Measurements taken after 10 minutes of warm-up.
  • 100% Average: Gm = 4.1 ; Ia = 45 mA
  • Test Result: VERY STRONG

Tube 1: Gm = 4.3 ; Ia = 41.6 mA

Tube 2: Gm = 3.8 ; Ia = 45.8 mA

Additional Tests Performed:
  • Microphonics: Low. Tested and compliant for hi-fi use, including phono stages and guitar amplifiers.
  • Emission Quality: Excellent – Very strong and stable emission, without fluctuations.
  • Short Circuits and GAS: None.

Description

Matched pair of 6V6GT National Union Made in USA, belonging to classic American production from the fifties. Both tubes share the signature construction with smoked glass, black plates, and foil getter, highly sought after by enthusiasts of early National Union power tubes.

One tube bears the code 51-39, corresponding to the 39th week of 1951. The other code is not fully legible, but its construction confirms it as part of the National Union production from the same historical period.

The pair was selected on an Amplitrex AT-1000, with measurements taken after a ten-minute warm-up. Tube 1 recorded Gm 4.3 mA/V and Ia 41.6 mA, while Tube 2 measures Gm 3.8 mA/V and Ia 45.8 mA. Considering transconductance and plate current together, the values are consistent for use as a pair in numerous push-pull output stages compatible with the 6V6GT.

Both showed very strong and stable emission, low microphonics, and no gas, shorts, or fluctuations. They are therefore suitable for vintage hi-fi amplifiers, guitar amps, and other power stages designed for the 6V6GT.

Regarding sound, American National Union tubes from this era are generally appreciated for a full-bodied, natural, and musical presentation, with rich mids, good dynamics, and defined high frequencies without excessive aggressiveness.

One of the two tubes has a crack on the plastic base, clearly visible in the photographs. During verification, this defect did not cause any electrical or functional anomalies: the tube proved stable and perfectly operational. However, normal caution is recommended during insertion, extraction, and handling, avoiding lateral pressure on the base.

These are used, tested, and fully functional vintage tubes, with partially worn but still legible markings. Supplied in custom Vacuum Tubes Treasures boxes.

A charming Fifties National Union pair, selected for their black plate construction, high emission, and authentic American production.

Condition:

  • Status: Vintage Tubes - Tested and fully functional. Supplied in our custom box for optimal protection. 
  • Functionality: Perfectly operational, with excellent test results.
  • Cosmetic Condition: Good – Markings partially worn, but still legible. 

    One tube has a crack on the plastic base, visible in the photo. This is an exclusively cosmetic defect that does not affect performance, as verified during testing. See photos for details.

Manufacturing Code: 

  • 51-39 → RMA/EIA Open Date Code → manufactured in the 39th week of 1951
  • KR S → undecipherable, identifiable by construction features. 1950s

Discover why our tubes 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
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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.

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