True NOS NIB CBS-Hytron USA 6BK7B Black Plate Top  Get Vacuum Tube 100+%
- Ships in 1 business day or less.
- Calculated at Checkout
Tube Type / Number: 6BK7B
Actual Brand*: CBS-Hytron
Printed Brand: CBS
Quantity: 1 Piece-Single
Matching Date Codes?
Plate Construction: Black
Getter Construction: Top 
Country of Manufacture: USA
Visible Date Codes:
Lettering Condition: 50 Percent
Number of Mica Spacers: 2
Mica Shape: Round Saw
Smoked Glass? Clear
Engraved Base? No
Boxes (always included): All Original
Tested For & Matched By: Gm (General Mutual Transconductance)
Gm Test Results: 66/70
Minimum Good Value: 43/43
NOS Test Value: 66/66
Life Calculation: 100+% (where 65% = fail)
Tests as NOS?: Yes
True NOS?*: Yes
** 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.
Vintage & NOS