 Label: Brimar Type : 6BW7 This is an equivalent to the EF80 general purpose RF pentode. A bit noisy for audio applications although it has been used. |
 Label: Mullard Type : EF83 Valve Code : 4G Factory Code : D Marked "Imported" this was manufactured at the Valvo Factory in Hamburg, Germany. The EF83 is a vari-μ (remote cut-off) pentode design for audio use in, for example, AGC circuits in tape recorders. |
 Label: Mullard Type : EF86 Valve Code : 8Y5 Factory Code : L Marked "Foreign" this was made in the Mazda factory in Brussels, Belgium. The EF86 is a purpose designed low-noise pentode for audio applications. |
 Label: Telefunken Type : EF86 Valve Code : 213 This has the famous Telefunken diamond on the base. Notice how different the construction is to the Mullard examples. |
 Label: Mullard Type : EF86 Factory Code : B This one is British, made at the Blackburn factory. |
 Label: Mullard Type : EF183 Valve Code : I4 Factory Code : B Another Blackburn made, British valve. A vari-μ, frame grid, RF pentode. Not suitable for audio. |