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We are the Historic TubeMuseum, Tuxedo Park, New York Established in 1928 as a premier research facility in Tuxedo Park, New York, that attracted such brilliant and most visionary minds of the twentieth century - Albert Einstein, Werner Heisenberg, James Franck, Niels Bohr and Enrico Fermi to name a few.  The Tuxedo Park lab attracted these top-flight scientists who experimented with audio, sound, time measurement, and radar (first klystron tube). Welcome to the ...

 Historic TubeMuseum, Tuxedo Park, New York - and Sarasota Florida

TUBEMUSEUM NEW YORK

NATIONAL UNION 6SL7GT "BLACK-GLASS" Phenomenal TUBES!

phe·nom·e·nal/fəˈnämənəl

1. Very remarkable; extraordinary.

2. Perceptible by the senses or through immediate experience.


FEEDBACK

6SL7-GT VT-229 NATIONAL UNION USA BLACK GLASS MATCHED PAIR TUBES NOS 1950s - Picture 3 of 10


RARE OLD-WORLD 1950's U.S.A. QUALITY
Manufactured by the HISTORIC 
NATIONAL UNION (N.U.) TUBE CORP. INC.


NOT JUST A 6SL7-GT, BUT A WHOLE NEW EXPERIENCE 
IN ENHANCED SOUND and REMARKABLE 1950's HISTORY!


TESTED N.U. NOS 6SL7-GT U.S.A.
RARE MATCHED PAIR of DOUBLE-TRIODE TUBES



NOS 1950's NATIONAL UNION 
NOS 6SL7-GT
DOUBLE-TRIODE AUDIO FREQUENCY TUBES
MATCHED PAIR


RARE OLD-WORLD U.S.A. QUALITY

"BLACK-GLASS" BLACK PLATES!

 REAL QUALITY FROM 1950's ERA AMERICA
NATIONAL UNION 6SL7-GT
NOS MATCHED TUBES!
HOLY-GRAIL QUALITY 
of the 6SL7-GT

6SL7-GT VT-229 NATIONAL UNION USA BLACK GLASS MATCHED PAIR TUBES NOS 1950s - Picture 1 of 10

ALL ARE ACTUAL PICTURES of the tubes and boxes you will receive

LAST REMAINING REAL SURVIVORS
with HIGH TEST SCORES!

THE "PERFECT" 6SL7-GT NOS TUBES
FOR YOUR AMPLIFIER
PERFECT MUSICAL INSTRUMENT OR AUDIO AMPLIFIER TUBES!


The 6SL7 is an octal preamp tube prized by guitarists for its rich, punchy tone, smooth overload, and enhanced attack. It is predominantly found in vintage, hand-wired, or modern boutique tube amplifiers.
Notable guitar amps that use 6SL7 tubes include:

... and other great boutique 6SL7 amps!





Manufactured by the HISTORIC 
NATIONAL UNION TUBE CORP. INC.
HISTORIC 1950's TUBES 
MADE IN 
THE UNITED STATES of AMERICA


Two black glass matchbox tubes with green printed text reading “6SL7-GT VT-229 National Union USA 2-18” on a green background.

BOTH TUBES MADE IN 1952 (52-18 = 1952, 28th week & 2-31 = 1952 )

National Union, had itself been formed by the merger of four smaller radio tube companies in 1928. The actions of Radio Corporation of America (RCA) appear to have driven the National Union Radio deal. In this deal, RCA lent the newly formed National Union Radio two million collars for a period of five years at 5 percent interest. The National Union Radio Corporation also entered into a reciprocal license agreement with RCA, General Electric (GE), and Westinghouse to manufacture radio tubes under the patents owned by these companies. This provided RCA, GE, and Westinghouse with greater control over the cost and production of tubes used by their products and a ready market for the radio tubes that would be manufactured by National Union Radio. The National Union Radio Corporation remained a major manufacturer of radio and television tubes for several years after 1929. It continued to operate under that name until June 1954, when it became the National Union Electric Corporation. In November 1954 the company sold its TV tube manufacturing facilities to Sylvania. Finally, in 1960, National Union Electric merged with Eureka-Williams.

Name:National Union Radio Corp.; Orange (NJ)    (USA)  
Abbreviation:national16
Products:Model types Tube manufacturer
Summary:
National Union Radio Corp., Orange, New Jersey: Tyne, "Saga of the vacuum tube" page 359: "This corporation was formed in 1929 by the merger of Sonatron, Magnatron, Marathon and Televocal. It was licensed by RCA. 

The company operated a separate factory in Lansdale, Pennsylvania during World War Two for military tube manufacture.The company also developed and made a range of transistors in 1952-54. 

A full range of radio panel/dial lamps was made and in the late 1930's, a "Serviceman's Kit ' of multiple lamps was available. Very early NU lamps seen have the full name stamped into the base.

Founded:1929
Closed:1954
Production:1929 - 1954
History:
The National Union Radio Corporation was incorporated in September 1929. It came about to merge the tube manufacturing interests of four companies: 1) The Connewey Electric Laboratories of Hoboken, New Jersey, manufacturers of Magnetron tubes. 2) Northern Manufacturing Co of Newark, New Jersey, makers of Marathon tubes. 3) Sonatron Tube Co of Chicago and 4) Televocal Corporation of New York City. The New York "Times" carried the sale of Northern Manufacturing to National Union on October 1st, 1929. Two factories were utilised - in State Street and at McCarter Highway, Newark. The main products were radio tubes. Sylvester Webster Muldowny was president of the new company from the outset and was in office until the middle of World War Two. He was born in 1899 and had a vocation in the banking industry, having been in the Bond Department of the Chicago Trust Co from 1921 to 1924. He was at Lehman Bros from 1924 to 1929. Administration offices of National Union were at the American Insurance building at 15 Washington Street, Newark. According to the "Altoona Mirror" in their issue dated September 2, 1929 capital of the company was US$18 million. The major shareholders were Muldowny, Lehman Bros and Sears Roebuck.
As a relative newcomer to the tube industry, National Union made all the standard receiving types of the time and also some odd types as replacements. It did not involve itself in researching or developing new types of tubes. Initially tubes were branded with the type number and this was preceded with NV, NX or NY, depending on the tube type. Around 1935 all tube type numbers were preceded with NU-. The hyphen was dropped apparently in late 1935 or early 1936 and a while later the NU prefix was discontinued. Tubes were only identified by the relevant type number. In 1939 Muldowny became interested in the possibility of the company making tubes that may be needed for any military action that might develop. Over the following few months the Board discussed this several times and at the Board of Directors meeting on December 12, 1941 it was reported by the Chairman that he was going to propose that the Government finance a new building for work on wartime tubes. The application to the Defence Plant Corporation was for US$1,166,000 for building of the new factory, which was to be located in Lansdale, Pennsylvania. The company was offered a "very fair lease" for this. The directors agreed with the proposal.
The Bendix Company was very early with an initial order of 10,000 tubes and there was an order from the U S Signal Corps. Western Electric followed these with an order for 40,000 tubes. Some British designed military tubes, such as the MOV VT90 and NT99 "micropup" radar tubes were made in 1942 and 1943. In the long run, Muldowny was somewhat pessimistic about the profit that could be made on military tubes. Not all was good for National Union during the early 1940's as Philco had been buying up shares in NU, to a point where it had a majority shareholding. References were in corporate minutes about a possible merger. Possible problems with tax was the main thing that induced Philco to withdraw. Another thing was the court case of Ripka V Philco Corporation in which the plaintiff sued Philco for return of monies paid to Philco for shares. The sale had been made by the plaintiff on the (misinformed) understanding that the merger was a "done deal". Judgement in the Southern District Court of New York was handed down for the plaintiff late in 1945.
At the end of World war Two National Union turned its Lansdale Plant over to commercial tube manufacturing. In 1952 the company began research into transistors and developed two main types - junction and point contact. This was done at the N. U. Semiconductor Division at Hatboro, Pennsylvania. Production ceased by 1954. The transistors were relatively expensive; for example, the T21A was listed in the 1953-54 catalogue for US$ 61.25 each. National Union transistors are now considered quite rare but they are easily identifiable as they used a green casing and silver printing. National Union Radio Corp continued operating until June 1954 when it was renamed National Union Electric Corporation. Five months later the TV tube plant was sold to Sylvania. National Union Electric merged with Eureka Williams in 1959/60. At the time they were known as heating and air conditioning manufacturers. Eureka Williams was acquired by Electrolux in Sweden in 1974.
IS BLACK-GLASS BETTER?


..."The coating on the plates is used to dissipate heat from the tube components. At one point it was only made with nickel making the finished color black, during WWII once nickel became short, aluminum was used instead making the finished color dark grey. This became the adopted manufacturing process until the early 1950's or so.

So, as you say the plate color gives us a a good marker of when the tube was made, rather than a direct indication of the sound quality. Since the black plate process is older, those tubes are becoming more scarce, so more costly."..


Why buy to from sellers who don't even test or show you the real test results? 

Ask yourself this question: Why should I buy to from sellers who don't even test or show you the real test results, and only tell you what tester they have?

IN ADDITION: 

These tubes are individually sound-auditioned in our preamp to guarantee perfect performance

Why buy to from sellers who don't even test or show you the real test results? 

SEE THE ACTUAL AMPLITREX AT1000 TEST RESULTS IN THE PHOTO SECTION!


PAIR 2: (AVAILABLE)

Tube 1: 1,400/1,400
Tube 2: 1,400/1,400




ACTUAL TEST MEASUREMENTS SO YOU CAN BE "SURE" YOU'RE GETTING THE BEST! 

Both tubes test and appear either never-used; just stored! 
For the age of these tubes they are in remarkable condition!



- RARE NO LONGER MADE
- OLD-WORLD 1950's NATIONAL UNION QUALITY
- PERFECT SOUNDING TUBES
- RARE 1950 ERA TUBES MADE IN U.S.A.

TubeMuseum tested tubes takes the guesswork out of the process of selection delivering you the best Audio tubes that possibly can be.


Low-Noise Tested Microphonic Free

No H-to-K Leakage (Heater-to-Cathode) No leaks (0) zero!

You would be surprised how many tubes are "sold elsewhere with unreported and hidden" Heater-to-Cathode leaks! Any H-to-K leak will prevent a tube from reaching it correct operating point and could damage your preamp, so be sure and secure with Tube Museum Tested Tubes!


Terms of Auction

YOU GET TWO (2) TUBES AND BOXES EXACTLY AS DISPLAYED!

Domestic & International Buyer's Terms of Auction

International Buyers - Please note: Import duties, taxes, and charges are not included in the item price or shipping cost. These charges are the buyer's responsibility. Please check with your country's customs office to determine what these additional costs will be prior to bidding or buying. We do not low declare and we insure for full value.

We do not guarantee that your tester, or your tester's measurements will be the same as the Amplitrex AT-1000. Older testers, different testers, or the same tester may report different test measurements, and may not measure the same tube meaningfully (due to current dependency), accurately (due to calibration difficulties) or consistently (due to internal circuit drift) There is no warranty or returns based on what any other tube tester reports.

Per eBay's terms of service which every eBay account holder must agree to as part of being an eBay member, a bid is a legally binding contract. Please read the Terms & Conditions carefully before bidding. By bidding on this auction, you understand and agree to eBay's terms of service as well as all terms and conditions mentioned here.

Item must be in original condition including cosmetic lettering on tubes so handle with white-glove care, un-used with all original boxes, packing material, environmentally safe cornstarch pellets, and shipping box. ALL RETURNS subject to a handling charge if returned in different condition than received. Absolutely NO RETURNS on special orders or best-offer deals.

All exchanges must be pre-paid and returned in original packing, complete with no sign of wear or abuse, exactly the same condition as it was when you received it. In the event that the product is not in the same condition, and does not test the same as you received it, you will be subject to a refusal and return, a determined restocking fee, repair charge, or disqualification. RETURN AUTHORIZATION (RA) number and instructions is required before sending any items. Shipping and handling charges are non-refundable.

We do not guarantee that your tester, or your tester's measurements will be the same as the Amplitrex AT-1000. Older testers, different testers, or the same tester may report different test measurements, and may not measure the same tube meaningfully (due to current dependency), accurately (due to calibration difficulties) or consistently (due to internal circuit drift) There is no warranty or returns based on what any other tube tester reports.

THE COST OF ALL USA SHIPPING INCLUDES INSURANCE, TRACKING NUMBER AND DELIVERY CONFIRMATION

We do not low declare and we insure for full value.

International Buyers - Please note: Import duties, taxes, and charges are not included in the item price or shipping cost. These charges are the buyer's responsibility. Please check with your country's customs office to determine what these additional costs will be prior to bidding or buying.


 Visit this seller's eBay Store! 

 TUBEMUSEUM NEW YORK

REAL NATIONAL UNION 6SL7GT "BLACK-GLASS"  Phenomenal TUBES!

phe·nom·e·nal/fəˈnämənəl

1. Very remarkable; extraordinary.

2. Perceptible by the senses or through immediate experience.


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