THE GREAT MULLARD MAGIC BLOG — tube faults

Mullard used a few dodges to ensure that blemished face plates were not used in tube manufacture such as when fitting the EHT connection in the cone of the 12 inch tube, this would always be located immediately above the gather or shear marks so that when the tube was fitted in the set, the tube mask would hide these marks - pretty clever. Otherwise, it was a matter of 100% inspection and selection and this is how it was done.   Firstly, only blemishes which could be seen from a distance of  3 feet 6 inches distance either under...