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Thorn 200W SLI/H HO linear Low pressure sodium lamp got this lamp today, was pleased to add a SLI/H lamp back to my collection (I used to have a few but traded/gave them to other collectors at one point) I also got it because I was quite curious to measure its electrical characteristics given the struggle several members have had running these lamps for today I started with a simple 150W SON choke as is generally given as the closest compatible gear and results where interesting, when the lamp struck current was about 1.2A, then slowly dropped to about 1A with the voltage rising quite high to 175V during the first stages of warm up (which is why I suspect some members lamps go out as 175V is really pushing it for 240V OCV so if your mains voltage is say 230V I could see the lamp going out) then as the lamp warmed up some more it dropped all the way to 115V 1.75A, but I noticed the ignitor was still ticking away slightly so I disconnected it and the lamp voltage rose to about 125V and the current dropped to about 1.67A where it stayed more or less (wavering up and down slightly) and the lamp seemed nice and stable (I suspect this lamp might have quite a high re-ignition peak voltage every zero-crossing that was keeping the ignitor active slightly, but I dont have an oscilloscope to verify that) lamp specs are officially 145V 1.55A so its not too bad but the current is a little high, so it will be interesting to see if I can figure out a better solution :) (the main important factor is the lamp current as the cathodes are most sensitive to that, and its worth noting as current increases lamp voltage will drop, which why some members have had current suddenly shoot up with the lamp voltage suddenly dropping and because the of the lower lamp voltage there is more voltage across the choke so it pushes more current through the choke and then just ends up running away, usually on GEC 60W and 200W SLI/H lamps) all in all very happy to have another SLI/H lamp again and its been very interesting to study its electrical characteristics and I hope others find it interesting/helpful in running their own SLI/H lamps :) I will be conducting some more testing in the days to come to see if I can produce a better result (I am quite curious to see how the setup I used for my F48T12/SHO tube will do for example)

Thorn 200W SLI/H HO linear Low pressure sodium lamp

got this lamp today, was pleased to add a SLI/H lamp back to my collection (I used to have a few but traded/gave them to other collectors at one point)

I also got it because I was quite curious to measure its electrical characteristics given the struggle several members have had running these lamps

for today I started with a simple 150W SON choke as is generally given as the closest compatible gear

and results where interesting, when the lamp struck current was about 1.2A, then slowly dropped to about 1A with the voltage rising quite high to 175V during the first stages of warm up (which is why I suspect some members lamps go out as 175V is really pushing it for 240V OCV so if your mains voltage is say 230V I could see the lamp going out) then as the lamp warmed up some more it dropped all the way to 115V 1.75A, but I noticed the ignitor was still ticking away slightly so I disconnected it and the lamp voltage rose to about 125V and the current dropped to about 1.67A where it stayed more or less (wavering up and down slightly) and the lamp seemed nice and stable (I suspect this lamp might have quite a high re-ignition peak voltage every zero-crossing that was keeping the ignitor active slightly, but I dont have an oscilloscope to verify that)

lamp specs are officially 145V 1.55A so its not too bad but the current is a little high, so it will be interesting to see if I can figure out a better solution :)

(the main important factor is the lamp current as the cathodes are most sensitive to that, and its worth noting as current increases lamp voltage will drop, which why some members have had current suddenly shoot up with the lamp voltage suddenly dropping and because the of the lower lamp voltage there is more voltage across the choke so it pushes more current through the choke and then just ends up running away, usually on GEC 60W and 200W SLI/H lamps)

all in all very happy to have another SLI/H lamp again and its been very interesting to study its electrical characteristics and I hope others find it interesting/helpful in running their own SLI/H lamps :)

I will be conducting some more testing in the days to come to see if I can produce a better result (I am quite curious to see how the setup I used for my F48T12/SHO tube will do for example)

Image_from_iOS_2814929.jpg Image_from_iOS_281829.jpg Image_from_iOS_2814729.jpg IMG_0913.JPG Image_from_iOS_2814529.jpg
File information
Filename:Image_from_iOS_2814729.jpg
Album name:Lightbulbfun / My Lamps
Manufacturer:Thorn
Type/Model:SLI/H HO
Wattage:200W
Date manufactured:November 1982 (date code 11)
Filesize:2837 KiB
Date added:15 Sep, 2020
Dimensions:2730 x 2048 pixels
Displayed:40 times
URL:http://80.229.24.59:9232/gallery/displayimage.php?pid=14596
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Comment 1 to 10 of 10
Page: 1

Lightbulbfun   [15 Sep, 2020 at 09:10 PM]
I did some further experimenting with this, it turns out you do need to leave the ignitor in circuit or the lamp will go out eventually, so I feel the 200W SLI/H HO does need a leak transformer or high OCV ballast of some kind to function properly, and can not satisfactorily/easily run off a choke ballast on simple 240V mains, it would be interesting to try 2 90W Leak SOX ballasts in parallel but I have only the one sadly,

for those wondering about the choke+series capacitor setup it will also still go out there as well (and it goes out as as the voltage begins to drop which is weird, but I suspect its because the re-ignition peak voltage is still too high for that type of circuit)

I also did some reading of Lamp datasheets, and noticed that the original Mazda/AEI 200W SLI/H while shown is a thermal starter switch start circuit that the ballast still boosts the OCV to 320V , however the GEC 200W SLI/H lamp datasheet shows a regular choke type setup, it was interesting to see the different control gear setups for what are lamps of supposedly the same specification, I must get a GEC 200W SLI/H and see how it compares Smile (I dont have a data sheet for a 200W SLI/H HO lamp but I know those are electrically different a normal 200W SLI/H specs are 135V 1.6A a 200W SLI/H HO runs at 145V 1.55A)
Funkybulb   [16 Sep, 2020 at 12:46 PM]
Very interesting to experiment Smile
thorncollector   [16 Sep, 2020 at 11:05 PM]
gec 200w sli will run ss off a 90/55w sox choke in parallel, the ho lamp needs an as you say a high ocv leak transformer, as preheat is not possible with a ho lamp
Funkybulb   [17 Sep, 2020 at 05:12 PM]
I wonder if possable on 277 volt OCV?
Lightbulbfun   [17 Sep, 2020 at 05:54 PM]
nah I tried with the variac (270V) and it still went out eventually
lampy   [17 Sep, 2020 at 08:15 PM]
has no one got a genuine 200 watt leak transformer then for one of these?
Lightbulbfun   [18 Sep, 2020 at 03:13 PM]
a few lucky collectors do, but they are rare as rocking horse shit! any genuine SLI/H gear is really rare sadly
Slyspark   [18 Sep, 2020 at 08:15 PM]
I have the proper, genuine ballast to run one of these on!
Andy   [18 Sep, 2020 at 09:50 PM]
I can only dream of finding the correct gear for these lamps.
Funkybulb   [19 Sep, 2020 at 04:33 AM]
This will be interesting to experment on 480 volt OCV then

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