Editing 6SN7 (section)

==History==
[[File:6SN7russ.JPG|thumb|Soviet version ''6Н8С'']]

The 6SN7 was originally released in 1939. It was officially registered in 1941 by RCA and Sylvania as the glass-cased '''6SN7GT''', originally listed on page 235 of RCA's 1940 RC-14 Receiving Tube Manual, in the Recently Added section, as: '''6SN7-GT'''. Although the 6S-series tubes are often metal-cased, there was never a ''metal-envelope'' 6SN7 (there being no pin available to connect the metal shield); there were, however, a few glass-envelope tubes with a metal band, such as the '''6SN7A''' developed during World War II - slightly improved in some respects but the metal band was prone to splitting.{{citation needed|date=October 2014}}

Numerous variations on the '''6SN7''' type have been offered over the years, including:
* '''7N7''' (Sylvania 1940, short-lived [[Tube_socket#Loctal|loktal]]-base version),
* '''1633''' (RCA 1941, also for 26-V radios),
* '''12SX7''' (RCA 1946, intended for use in 12-volt aircraft electronics),
* '''5692''' (RCA 1948, a super-premium version - not exactly identical - with guaranteed 10,000-hour lifetime),
* ''' ''6Н8С'' ''' ([[Cyrillic]], Soviet version, {{Circa|1950}}, in Latin letters: '''6N8S''');
* '''6SN7 DDR''', '''6Н8М''', '''E1606''' (='''CV278'''), '''OSW3129''' versions with different/larger glass envelopes;
* '''6042''' (1951, another 1633 type), and
* '''6180''' (1952)
* '''6SN7W''' (1956; a more rugged military version, glass envelope with metal band)<ref>{{cite web|title=6SN7W at the National Valve Museum|url=http://www.r-type.org/exhib/aad0076.htm}}</ref>

The American military designator for the 6SN7GA is '''VT-231'''. The British called it '''CV1988'''. European designations include the 1942 '''ECC32''' (not an exact equivalent), '''13D2''' and '''B65'''.

The 6SN7 has a 6.3 V 600 mA heater/filament. The 12-volt 300 mA filament equivalent is the '''12SN7GT''' or '''12SN7GTA'''. The '''14N7''' is the Loktal version of the 12SN7GT. There was also a comparatively rare 8V '''8SN7''' for 450&nbsp;mA series-string TV sets) and 25 Volt/0.15 Amp heater version: '''25SN7GT'''.