The 7V7 is a sharp-cutoff pentode vacuum tube designed for high-frequency radio frequency (RF) and intermediate frequency (IF) voltage amplification stages in superheterodyne receivers and communications equipment. Featuring a 6.3V filament rating with a 450mA current draw, it utilizes an 8-pin lock-in (loctal) base in a T-9 glass envelope construction. Manufactured by companies including Sylvania, RCA, and Tung-Sol, this tube provides high transconductance and stable performance for mid-century receiver chassis requiring precise gain handling without automatic volume control feedback variations