hard valve
Electronics (now chiefly historical )
noun
A thermionic valve or tube with a hard vacuum, or evacuated sufficiently for any remaining gas not to affect its performance.
Origin
Early 20th century; earliest use found in Wireless World.
- letter bomb
- letter bomber
- letter bombing
- letter book
- letter-bound
- letter box
- letterbox
- letter card
- letter carrier
- letter case
- letter chute
- letter clip
- letter creditive
- letter cutter
- letter cutting
- letter drop
- letter dropper
- lettered
- letteree
- letterer
- Letterer–Siwe
- letter-for-letter
- letterform
- letter founder
- letter founding