Many thanks there Betail Sauvage. Léopold Bernard then may have set the tone for other tube sources like Kilby, Sauer, etc. where the upper rung metals were always sold in serialized sets. So 1000 tubesets & I wonder what type attrition thru the years would result in a residual number now beings a % of the 1000 gross?

Cheers,

Raimey
rse