[AMRadio] National tubes - Chinese 833's?


John Lyles jtml at losalamos.com
Wed May 23 16:40:14 EDT 2007


Few years ago I bought a bunch of 5C22 thyratrons from Richardson. They came in National tube cartons. None would fit the standard Johnson jumbo 4 pin socket due to the little alignment pin being in the wrong place. I had to cut the pin off to make them work, it slides into the base slot like a bayonet and turns to lock the tube into the base. After this encounter, I was worried. My concern was warranted when the tubes lasted no longer than 6 months before they began to mis-trigger. They were used as the crowbar trigger device in a big 15 kV 6 Amp plate supply.  We could not live with constant firing of crowbar protection circuit. I never used that brand again, oulled them all out and trashed them. Switched to E2V from the UK. These particular National tubes were marked made in USSR I believe. 

73
John K5PRO


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