|
The Radio Electronics Television Manufacturers' Association was formed in 1953, as a result of mergers with other trade standards organisations. It was principally responsible for the standardised nomenclature for American vacuum tubes. American made tubes bear a RETMA designation to allow for easy cross-referencing. The RETMA tube designation does not incorporate the purpose of each tube in the designation. The Anglo-European Mullard-Philips tube designation does include tube use information in the designation. *First figure group: indicates heater/filament voltage; 0 means a cold-cathode tube * Letter group: letter(s) indicate the serial order of assignment of the designation. * *Letters U, V, W, X, Y and Z are commonly used for rectifiers * *S as a first letter indicates single-ended tubes, related to grid-cap tubes. * *S as a second letter indicates single-ended tubes. * *Combinations like AB, AC, AD and AE were used when all the single letters were used up. * *L as a first letter often indicates a lock-in (Loktal) valve. * *P as a second letter indicates a CRT. * *Wherever possible, the 12V equivalent of a 6V tube had the same letters, just 12 instead of 6. ::Occasionally the same letter groups were used for differing tubes but only where the last number would be different making the designation unique. For example there is a 12AV5 (beam tetrode), 12AV6 (double diode, triode) and a 12AV7 (double triode). * Second figure group is the number of useful elements (including the heater if this is separate from the cathode); in metal tubes the shell counts as one element. Internal shielding also counts, but base shielding does not. Electrodes connected together internally are counted as one element. There is an inconsistency in the way tapped heaters or filaments are counted. For example, the 12BH7 (double triode with separate cathodes) counts the centre tapped heater as one useful element, whereas the 12BY7 (pentode) counts the centre tapped heater as two useful elements. There are also inconsistencies in the way internal screens are treated. In the 6BX6 (pentode with g3 brought to its own pin), the screen around the assembly is not counted, whereas the 6BR7 (also a pentode with g3 brought to its own pin) has its similar screen included.〔Brimar Radio Valve and Teletube Manual (Edition No. 7)〕 In the case of a CRT, the second figure group indicates the type of phosphor the tube face was coated with. Additional letters: *A,B,C Improved backward compatible versions *E 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「RETMA tube designation」の詳細全文を読む スポンサード リンク
|