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Very rare 1959 – Mil’ wrinkle glass- Whyteleafe “A” Production !

This is a CV 4024 (military grade long live ECC81) by Mullard in1959 in the Whyteleafe “A” production plant in the UK. The tube has military early wrinkle glass, halo getter , copper grid posts and rounded plates, see pictures.  Extremely rare tube!

The tube has the very scarce Whyteleafe “A” factory mark; which made select tubes only for the military. Used in British military radar installations. They are long-lived and sweet in hi-fi applications.

 Tubes with matching triode systems; see test results. The halo getter has a non standard structure, I have never seen this construction before. See first picture.

Sonics

The very early British ECC81 tubes from Mullard are famous for their beautiful sonic character. I refer to the many threads on the web for more information. This CV4024 is one of the finest from Mullard in the ECC81 types.

Note: if your system is to “warm”, this tube is not a first choice. ECC83 tubes of Philips, Valvo or to a lesser extent Telefunken are to be considered in that situation. 

Test results*

Very healthy tube with excellent specs!

Valve V39

Ia (plate current): Transconductance (Gm): Gas test, Shorts test:

9,5 / 9,8  mA  5,5 /5,8 mA/V OK

=  NOS / NOS =  NOS / NOS

Where NOS is : Ia = 7 to 14 mA, Gm= 4,5 to 6,5 mA/V. 

  *  For test methods and factory specification read the tube testing page.

Short description