ECC81, MULLARD, YELLOW PRINT, Tk3 B3I3, BLACKBURN, MARCH 1963 PRODUCTION

ECC81, MULLARD, YELLOW PRINT, Tk3 B3I3, BLACKBURN,  MARCH 1963 PRODUCTION

On offer today is a lovely Mullard Yellow Print, ECC81 carrying the date code for March 1963.       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 = 4.7 mA/V

Section 2: Ia = 10 mA; gm = 4.5 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.