On offer today we have a lovely matched pair of Mullard EL37.
Against the nominal AVO specification for 100% emission of :-
Ia =100 mA; gm = 11.0mA/V @ Va = 250V; Vg = -15V
Obtained results were:-
y10: Ia = 72 mA; gm = 9.0 mA/V
Y24: Ia = 70 mA; gm = 9.0 mA/V
As you can see, these results are slightly lower than nominal but should give superlative performance in Push-Pull output applications as the matching of both gm and Ia is superb.