Outstanding features of the 827-R include its use of (1) thoriated-tungsten filament with special low-resistance, multiple-ribbon leads that handle high current without heating, (2) two multiple-ribbon grid leads that minimize the effect of lead inductance and (3) an entrant metal header-type construction. The header-type design serves not only as a low inductance terminal for the screen but facilitates isolation of the input and output circuits. As a result, neutralization of the tube is unnecessary except at the very highest frequencies. The plate of the 827-R is air-cooled by means of a highly efficient finned radiator which forms an integral part of the tube. This radiator must be cooled by means of a vertical flow of air from a properly installed air-cooling system.
The 827-R is a remarkable beam tetrode that opens the way for new economies of tube installation and application. It is the answer for dependability of high power at the ultra highs.
