Tests NOS Matched Quad (4) RCA USA Type USN-CKR-77 Silver Plate Vacuum Tubes

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Tube Type / Number: Type USN-CKR-77
Actual Brand*: RCA
Printed Brand: RCA
Quantity: 4 Pieces-Matched Quad
Matching Date Codes? No
Plate Construction: Silver Smooth
Getter Construction: Bottom D Foil
Country of Manufacture: USA
Visible Date Codes: K2E & S5 & S5 & K3E
Lettering Condition: 90 Percent
Number of Mica Spacers: 2
Mica Shape: 2 U
Smoked Glass? Clear
Engraved Base? No
Boxes (always included): Mixed Generic & Original
Notes: ST
Tested For & Matched By: Gm (General Mutual Transconductance)

Gm Test Results: 46 & 46 & 48 & 48

Minimum Good Value: 30
NOS Test Value: 46
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.


All of our tubes are 100% guaranteed to arrive as described, test as described and to be void of any sound defects. We offer a 30 day return window from the day you receive the item.

PLEASE NOTE - While we accept returns for basically any fault, we DO NOT accept returns for buyer's remorse which includes buyers who decide they don't like the subjective tonal signature of a tube. We have had people exploit our generous return policy to tube roll on our dime so we have a strict policy against this behavior.

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