[keithw]

The tube shield is to block electrical interference. The functions of containing heat, retaining tubes, etc. are secondary. Some of the foreign tubes, Italian and I recall, had the shielding material painted onto the tube.

Recently worked on a GE I think it was that was just being a pain to allign. Then I noticed that one of the tubes had a shield base and no shield. After intalling a shield things went much better.

keithw