typically begin with "7" (for 6.3-volt types) or "14" for 12.6-volt types. This was fudged by specifying the heater voltage as nominally 7 or 14 volts so that the tube nomenclature fitted. Battery types (mostly 1.4-volt) are coded "1Lxn", where x is a letter and "n" a number, such as "1LA4". Russian loctals end in L, e.g. 6J1L. European designations are ambiguous; all B8G loctals have numbers either in the range: 20–29, (such as EBL21, ECH21, EF22) except for early tubes in the series: DAC21, DBC21, DCH21, DF21, DF22, DL21, DLL21, DM21 which have either B9G or octal bases, the change to Sylvania's locktal standard coming in 1942 or 50–59 (special bases, including the European 9-pin lock-in base), but other types are in the same range (e.g. while EF51 is B8G loctal, the EF55 is 9-pin loctal, B9G, and the EL51 has a side-contact P8A base). Other loctals Nine-pin loctal bases, B9G, include the 1938 Philips EF50, EL60 and some type numbers in the European 20–29 and 50–59 range; There is a different "loctal Lorenz" in the Mullard–Philips tube designation . Miniature tubes Efforts to introduce small tubes into the marketplace date from the 1920s, when experimenters and hobbyists made radios with so-called peanut tubes like the Peanut 215 mentioned above. Because of the primitive manufacturing techniques of the time, these tubes were too unreliable for commercial use. RCA announced new miniature tubes in Electronics magazine, which proved reliable. The first ones, such as the 6J6 ECC91 VHF dual triode, were introduced in 1939. The bases commonly referred to as "miniature" are the seven-pin B7G type, and the slightly later nine-pin B9A (Noval). The pins are arranged evenly in a circle of eight or ten evenly spaced positions, with one pin omitted; this allows the tube to be inserted in only one orientation. Keying by omitting a pin is also used in 8- (subminiature), 10-, and 12-pin (Compactron) tubes (a variant 10-pin form, "Noval+1", is basically a nine-pin socket with an added center contact). As with loctal tubes, the pins of miniature tube are stiff wires protruding through the bottom of the glass envelope which plug directly into the socket. However, unlike all their predecessors, miniature tubes are not fitted with separate bases; the base is an integral part of the glass envelope. The pinched-off air evacuation nub is at the top of the tube, giving it its distinctive appearance.