A quantity of six CV5080 pentodes, equivalent to commercial type EF37A and manufactured by Mullard. These appear to be used, are marked KB/DA with services broad arrow, and have been tested for mutual conductance on a two panel AVO meter. Unfortunately, these are below spec and the following results for each valve were obtained;

0.4mA/V, 0.4mA/V, 0.6mA/V, 0.6mA/V, and 0.6mA/V

The AVO manual recommends a figure of 1.8mA/V for a good valve.

Thanks for looking.