ECC81, MULLARD, OLD SHIELD, YELLOW PRINT, FACTORY CODE, Tk3 B4I4, BLACKBURN 1964 MANUFACTURE

 ECC81, MULLARD, OLD SHIELD, YELLOW PRINT, FACTORY CODE, Tk3 B4D1, BLACKBURN 1964 MANUFACTURE

On offer today is a lovely Mullard ECC81, a premium quality ECC81 carrying the date code for 1961.       Carrying good white print, it tests as excellent using my AVO Valve Characteristic Meter VCM163 with the following results: At Va = 250V Vg = -2.0V 

Section 1: Ia = 11 mA; gm = 5.6 mA/V

Section 2: Ia = 12 mA; gm = 5.9 mA/V

The specification for a new/100% emission valve is:

Ia = 10 mA; gm = 5.5 mA/V

As you can see, this result show a strong valve with excellent matching of each triode section within the envelope.