Re: Which lamp is older? « Reply #1 on: May 30, 2022, 07:16:57 PM » Author: HPS_250
The H33-1-GL/DX is definitely older since it was made before the 400w lamps were called H33GL-400/DX as they still are. If I remember correctly it’s likely from the 60s to around 1972/73. Unfortunately I don’t know the exact dates from the etches though, I’m sure some other members do.
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	Re: Which lamp is older? « Reply #2 on: February 21, 2024, 04:44:12 AM » Author: LightbulbManiac
The only date code I could decode is for the second lamp since on the first one I can't clearly see the date code. 57 = May 1967/1977
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	Re: Which lamp is older? « Reply #3 on: February 24, 2024, 12:56:10 PM » Author: wide-lite 1000
I'm gonna say the bottom one is older as the top one has the "R" in the etch . In the US at least , the "R" came out in the early 80's as a designation of a standard Mercury Vapor lamp.
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	Re: Which lamp is older? « Reply #4 on: February 29, 2024, 03:54:41 PM » Author: BT25
Top is from January, 1981. Bottom is from May, 1967.
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	Re: Which lamp is older? « Reply #5 on: February 29, 2024, 04:33:20 PM » Author: wide-lite 1000
I figured someone else could give a more detailed answer as to the dates .
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