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Osram 215V 80W 4-pin Lamp Ok, here is a weird one that I am looking for some help with, as I do not want to risk damaging it by trying to light it incorrectly. It appears to be a drawn wire filament and there are 4 pins on the base. It has a NATO stock number of 996-9602 which comes back with the interesting figure of 35/215 for the voltage. Of the four pins, one is not connected and measuring with my multimeter I get readings as follows: Pin 1 - Not connected Pins 2 - 3 = 37.5 ohms Pins 2 - 4 = 8.3 ohms Pins 3 - 4 = 44.6 ohms Can anyone advise, please..? We'd really love to see this one lit..! It is also shown as being intended for ships' navigation, but that's all we know. Keywords: Lamps

Osram 215V 80W 4-pin Lamp


Ok, here is a weird one that I am looking for some help with, as I do not want to risk damaging it by trying to light it incorrectly. It appears to be a drawn wire filament and there are 4 pins on the base. It has a NATO stock number of 996-9602 which comes back with the interesting figure of 35/215 for the voltage. Of the four pins, one is not connected and measuring with my multimeter I get readings as follows:

Pin 1 - Not connected
Pins 2 - 3 = 37.5 ohms
Pins 2 - 4 = 8.3 ohms
Pins 3 - 4 = 44.6 ohms

Can anyone advise, please..? We'd really love to see this one lit..! It is also shown as being intended for ships' navigation, but that's all we know.

Tungstalite_200V_60W_Drawn_Tungsten_Lamp_2.jpg Osram_215V_80W_4-pin_Lamp_Lit.jpg Osram_215V_80W_4-pin_Lamp~0.jpg GE_120V_50-100-150W_Clear_Demonstration_Lamp.jpg Royal_Ediswan_230V_15W_Green_Pygmy_Lamp.jpg
Lamp/Fixture Information
Manufacturer:Osram-GEC Ltd.
Model Reference:NATO 996-9602
Lamp
Lamp Type:Incandescent
Filament/Radiator Type:Drawn wire tungsten
Base:4-pin valve base
Shape/Finish:ST-78
Service Life:1000 hours
Burning Position:Vertical, base down
Electrical
Wattage:80
Voltage:35 / 215 / 250
Optical
Lumen Output:750 / 120
Physical/Production
Factory Location:England (location unknown at present)
Fabrication Date:Not known at present (Date code 30VB)
Application/Use:Ships Navigation
File information
Filename:Osram_215V_80W_4-pin_Lamp~0.jpg
Album name:Ria / Incandescent Lamps
Keywords:Lamps
Filesize:177 KiB
Date added:27 May 2025
Dimensions:1790 x 1260 pixels
Displayed:7 times
URL:https://trad-lighting.net/gallery/displayimage.php?pid=867
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Comment 1 to 5 of 5
Page: 1

Tuopeek   [Tue 27 May 2025 at 18:51]
Could this actually be a Barretter rather than a lamp? The different resistances could provide different volt drops. Although I have only ever seen ones with two filament but no tappings.
Max   [Tue 27 May 2025 at 19:25]
I have that lamp in the collection, and it is intended for naval application indeed. The reason for the filament tap is so the lamp can run either on standard AC supply (215 or 250 V), or on emergency DC battery supply (35 V). Its operation is straightforward: pin 2-4 should be the 35 V input due to its lowest impedance, pin 2-3 for 215 V operation, and pin 3-4 for 250 V operation. If you want to keep risks to a minimum, then run the lamp from a Variac at lower than specified voltages, this way you can also check that the right filament section is energized (small one for 35 V, large one for 215 V, and all of it for 250 V).

My lamp doesn't have the NATO code but the British Admiralty stamp on its bulb. Its date code follows the British ELMA system and is "33", which I would translate to September 1944 (1936 is another possibility but I doubt the lamp is that old, I'd need to trace its patent to be sure though).
Ria   [Tue 27 May 2025 at 20:05]
Thanks Max, I was sure you'd know..! I'll give it a try later and let you know.
Max   [Tue 27 May 2025 at 20:12]
Looking forward to seeing the lamp lit!
Ria   [Tue 27 May 2025 at 23:57]
We did a quick lash-up with croc clips on the pins and it worked fine, so we'll make up a project box with a lampholder on it so we can wire it up properly, watch this space Bulb Man

Edit: I found the date code, it shows 30 and the letters VB.

Comment 1 to 5 of 5
Page: 1