What’s the point of only one cathode guard? « on: December 19, 2021, 11:11:01 AM » Author: Bulbman256
I bought some USA made Philips tubes at home depo yesterday and only one end of the tubes had cathode guards. Why would you only cover one cathode up when both are needed for proper operation?
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	Re: What’s the point of only one cathode guard? « Reply #2 on: December 19, 2021, 01:31:07 PM » Author: Roi_hartmann
Isn't that quite common thing at least for lower wattage lamps (like 20w and under)?
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	Re: What’s the point of only one cathode guard? « Reply #3 on: December 19, 2021, 02:03:56 PM » Author: Bulbman256
They are F40T12 /dx lamps made in April of 2021, the production line stamps where 53 and 56, both tubes had only one cathode guard on the non etch end
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Collecting light bulbs since 2012, a madman since birth.

	Re: What’s the point of only one cathode guard? « Reply #4 on: December 19, 2021, 02:54:41 PM » Author: Patrick
The cathode guard supports the mercury capsule.  I've heard it speculated that Philips eliminated guards as a cost cutting measure, but had to keep one on Alto lamps in order to support this method of mercury dosing.
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	Re: What’s the point of only one cathode guard? « Reply #5 on: December 21, 2021, 06:52:18 PM » Author: Silverliner
The last batches of F32T8s made at Salina had only one guard. They were always guarded on both ends unlike the T12s.
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