NOS Matched Pair National Union NU USA JAN-CNU-25Z5 Black Plate rtl Vacuum Tubes

Tube Type / Number: JAN-CNU-25Z5
Actual Brand*: National Union NU
Printed Brand: NU
Quantity of Tubes: Matched Pair
Plate Construction: Black Smooth
Getter Construction: D Foil
Country of Manufacture: USA
Visible Date Codes: UL/IU & AI/G5
Lettering Condition: 90 Percent
Year Made:
Number of Mica Spacers: 2I
Glass Coating: Clear
Engraved Base? No
Boxes Included? Multiple Boxes - SOME Original, Some Generic
Notes: ST, 1 Tube Rattles

Gm Test Results: 59/59 & 59/59
Minimum Good Value: 40/40
NOS Test Value: 50/50
Life Calculation: 100+% (where 65% = fail)

Tests as NOS?: Yes
True NOS?*: No

** Please note, many tubes will test NOS but will actually have a few hours of use on them. A truly NOS tube will have excellent getter flashing condition, no dirt/grime, usually in the original box, and no filament deposits. If a tube is listed  as "tests NOS" but is listed as "not True NOS" please expect the tube to have a small amount of use *

All tubes have been tested using only the best tube testers. We have a large fleet of tube testers, and every single one of them has been calibrated within the last year by industry experts. We mainly use the Hickok TV-7D/U, but occasionally we may use a Hickok 539, 533A, or 600A.