The Mullard M8099 is a special quality version of the original 6AQ4 and was made for critical applications. The valve is a miniature single triode for use as a grounded grid amplifier, and thus at high frequency. The CV4070 identification is present on the reverse of the envelope.
This type of valve was designed for RF applications at VHF up to a maximum frequency of 250 MHz. These would include radio, television and radar. The equivalent noise resistance was given as 400 Ω.
The KB/D identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the D identifies the maker as Mullard Radio Valve Co., Mitcham.
The central triode with supports either side.
The Other Type designations on the envelope are CV4070 and 6AQ4. The CV has to include the factory of origin and thus we know this came from Mitcham in South London.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 46 mm tall.
