The CV2925 (commercially the EBF2) is a double diode pentode designed for use in low cost broadcast receivers. This exhibit has the Philips/Mullard late 1930s bright red metallising.
The valve is a high impedance variable μ pentode, with two auxiliary diodes all sharing a common cathode. In a superhet receiver one diode would be used for signal detection and the other to produce an AGC voltage to reduce the receiver sensitivity on strong signals and thus prevent overloading and distortion. The vari-μ pentode voltage amplifier in a low cost receiver would be the IF amplifier.
The metallising covers all but the area around the top cap.
The Ct8 side contact brass studs.
The classic envelope is 31 mm in diameter and, excluding the Ct8 base pins, is 91 mm tall.
