When working on a power amp outside of its case and of the normal form with mains transformer at one end and output matching transformer at the other. Assuming the valves don't extend too far. Aluminium sheet about 20 inches by 5 inches. Bend down the middle lengthways to a right angle and place between the transformers protecting the third corner. Hold in place with a pair of large cable ties or doubled/trebled up smaller ones, preferably with delatchable grips .
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
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