1,000 Watt Marconi Radar Systems Military Short Arc Searchlights

Newest acquisition. I spotted these behemoths a couple weeks ago and stayed with the bidding process until I snagged these powerful military Short Arcs. While they may remotely resemble the MegaRay, the light with the 90 degree mirror weighs 72 lbs and the straight output light weighs 60 lbs. The optic you see in front of the straight output configuration light is approx. 5.75" to give some idea of scale. I am expecting them to arrive any minute so some of my description may change as I confirm things. I brought them all the way over from North Wales, UK. Can you believe it....They were picked up on Tuesday morning and are almost here.

I've not been able to determine what they were prototyped for (These are Prototypes #2 and #3) but I would suspect some type of aircraft. Not that I am all that familiar with all military lighting, but I have never seen nor heard of anything like these so I have a feeling they never made "production". They don't really resemble any helicopter light I've seen so maybe they were developed for some type of fixed wing reconnaissance aircraft. No hits on Google other than the sales thread and a forum they were on before. They were made by Marconi Radar Systems, Ltd before they were absorbed by BAE so that puts these lights at somewhere around 1985 or earlier. Does anyone know if visible light is ever used to run or test radar systems? I have wondered if they are somehow related to radar systems. The seller had them for a couple of decades after buying them at a MOD military auction in 1991. They both function as designed and built. The second light has a rotating mirror in the head to deflect the light 90 degrees, other than that, they are the same. The switch box provides knobs for dimming and one to rotate the deflection mirror. Each one has an internal shutter so the light can remain on without any visible light being transmitted. Sort of like the VSS-3a and how it turns on in infrared mode so as not to give away its position inadvertently. The seller states that the input fuse is rated at 75 Amps and the system runs on 28 Volts so knocking off 1/3 of the power (as a guess), these could be 1500 Watt Short Arcs. I don't know beam spread at this point either but am hoping for 2 degrees max and better yet, 1 to 1.5 degrees.

At some point, I am going to try to get to my test range for comparison shots. However, I don't want to repeat my "tank lights" episode from years back in which my 2.2KW VSS-1 "tangled" with the local Police departments' 1.6KW NightSun. There are no PD choppers here so I'll just have to worry about the local patrol vehicles. To power them at the range, I'll need my 4.5KW, 240 Volt generator and the Lorain 29 Volt, 100 Amps Rectifier. I think the 240V/16.5 Amps from the genny will be enough but will run the Lorain in the field but will try it at home from the house 240V/30 Amp circuit first to measure. That's a lot of heavy stuff to handle so the beam shots won't be easy to get. And the genny noise plus what I expect to be an impressive beam will probably generate calls.





Cooling fan intake or exhaust, not sure yet




Separate Power Supply




Be Careful!




Switch Box




Front View




Profile




Right Angle device




OEM Crates




The Pair




The light is a full third larger than I had imagined. It is a monster but I don't think it's 80 lbs. Guessing 60 but will weight it later.

Fire Foxes 3 and typical Kleenex box with tape measure.




I just had to take the front lens off to see inside. I'm very surprised. The orifice the light is emitted from is about 1/4" to 5/16" in diameter. Makes me think this is a laser. It's kind of scary looking in there. But then it hits a Plano Convex lens and is dispersed. How much, I don't know. I've got a lot to look at before I fire one up. And then I don't want to melt anything I'm aiming at so will break out a leftover piece of 3/4" granite slab.

Re: Right Place At The Right Time - Vers. 2.0

A few more pics. Upon removal of the ignitor cover, I noticed that there is white "goop" over the surface of the main ignition coil. However, on all other coils like this that I have seen, the goop or other insulation is hard. This stuff looks and feels like it has turned to the consistency of Thermal Compound and the oil base has partially separated from the solid material. There is an oily film on many of the components and on the bottom and side of the ignitor housing. Anyone ever seen this?

Ignitor Cover




Ignitor Coil with Goop fallen off




More Goop where I don't think it should be - probably from shipping




More Goop thrown around




Warning




Ignitor identifier




Cooling Fan




Ignitor Cover with Goop

Re: Right Place At The Right Time - Vers. 2.0

incredible find Bob!!!!:twothumbs I'm jealous as hell! Lol
interesting with such a small light output orifice, I'm very curious!

Re: Right Place At The Right Time - Vers. 2.0

I love following you story-type monster-light-threads :twothumbs

Re: Right Place At The Right Time - Vers. 2.0

Thanks Driver!

More pics of the lamp and surrounding area

Finned "Snout" removed to reveal lamp and shutter device. The burn impression on the shutter reveals the beam to be about 5/8" in diameter as it hits the shutter.




There's a small motor that pivots the shutter out of the beams' path. The reflector is obviously an Elliptical as it's harnessed all output into the 5/8" diameter beam at the shutter and then after traveling another inch or so, it passes thru the .300" hole behind the shutter. From there, it has to travel about another 6" to hit the Convex lens where it is collected, diverged and sent out tightly collimated at about the size of the 5.75" lens according to the seller.




Front of the light, snout removed showing lamp support. One of the two bolts on the right was nearly falling out of the hole.




Lamp Close-up. Chamber looks to be about 1 5/8" in diameter. I didn't notice the "0.8" and smaller text in the reflector while taking the pic. I need to go back and see where it's coming from. Only markings on the front base so far are "49". I still don't know the power level of the light. I'll have to take readings with the ignitor cover off at some point. checking and setting focus will be a time-consuming task. The snout needs to be removed for each movement.




Much as I want to, I've decided to not remove the lamp until I have run the light just in-case something happens during removal and re-installation and I want to get the Volts and amps at the bulb so I know the power level and can get a new bulb made if the need arises.

Re: Right Place At The Right Time - Vers. 2.0

Just some guessing of output power. Based on the strip resistor in the power supply, the lamps running Voltage will be between 20.2 and 20.8. after start-up and boost. They have tapped the strip at 3 points and each tap lands on its own terminal which is marked with a Voltage range. The cable directly out to the ignitor and then to the Anode is on the "20.2V - 20.8V" terminal. My second guess is that the Amperage draw will be somewhere around 66% of the 75 Amp input fuse rating - so 49 Amps. 20.5 x's 49 = 1004 Watts. Once I finish re-insulating the 45KV ignition coil, I'll be able to fire it up and verify the numbers. I'm hoping for more than 1000 but logic tells me it will be right at 1000 Watts. Changed the title to reflect my guess. Doing lots of cleaning and polishing while I wait for the multiple layers of liquid electrical tape to fully cure on the coil. Maybe done by Wednesday.

Re: Right Place At The Right Time - Vers. 2.0

:twothumbs

Re: 1,000 Watt Military Short Arc Behemoths

Neat! Thanks for pics and data. Glad someone here got them, I considered bidding but shipping cost looked huge from UK (you obviously sprung for air freight).
For power supply, just fired up my AN/VSS-3 with a Mean Well RSP-1500-27 switch mode up to 56A output and will run on 120V, $335 + tax and shipping from PowerGate. Might work for you.

Re: 1,000 Watt Military Short Arc Behemoths

I mentioned in your VSS-3 thread about member Modamag's 2 remaining Lorain 29V/100 Amp rectifiers that will run off 120V. $150 each. He's in your area so you could pick one up, no shipping.

Re: 1,000 Watt Military Short Arc Behemoths

looking forward to seeing this thing fired up.

i dont think i will ever get anything bigger/badder/brighter than a Maxabeam, but to see one of these big beasts (60"CA, VSS3, Megaray, Locator etc) in action would be awesome

Re: 1,000 Watt Military Short Arc Behemoths

Hey BVH nice lights and great find! Having been a pilot for a while and from my time at Fort Rucker, my best guess would be that these were design to be some sort of quick-deploy beacon lights for military aircraft. What leads me to this conclusion is the rotating (or oscillating) mirror head on the one light. There was most likely a rotator also meant for the second which got lost along the way. I think that, with the rotator attached and operating, the beam profile and divergence will tell us more. Typically, aircraft beacons will have a slight upward angle of a few degrees as well as a certain spread, and will be configured such that the lower portion of the beam is near parallel with the ground or diverging about a degree from it.

When you get these babies fired up it should be more telling. Check the mirror, is it absolutely flat or does it have even the slightest convex shape to it? It may be hard to tell on visual inspection but will be much more obvious when operating. Also when operating, see if the beam really is deflected 90 degrees of if there is any upward angle along with a certain amount of divergence. Does the mirror actually rotate or is it a side-to-side oscillation? How fast is the rotation or oscillation? I was also noting the converging mount holes in the flanges on the light without the rotator head... can't really see the other side but this may be another clue. It does say "searchlight starter" on the power supply but that may not be very telling if it was a "generic" light starter used in other apparatus as well. Being prototypes this really has me curious :thinking:

Re: 1,000 Watt Military Short Arc Behemoths

Thanks for the thoughts, Zep. I've spoken to the Advanced Radiation Corp (ARC) guys a few times on lamp orientation. It is always best to orient the bulb so that when a light is in normal operation, the Anode is straight up. This is because all the brute forces of the flame are directed at the large Anode electrode - which is designed to take the heat and force. Cermax bulbs come with a warning not to operate them above 45 degrees above the horizon. This is because the thin Cathode is in front. Point it up too much and the flame will be blown back against it and damage occurs rapidly. This is the same configuration used in these lights. The Cathode is in front. If the lights are pointed up, the bulbs would most likely expire quickly. I can only conclude that they are made to run horizontal (an acceptable compromise) or possibly even run facing down - best for the lamp. The Anode in the VSS-1 was straight up. Perfect for the bulb since the light was used horizontally, not much up or down. My 600 watt helicopter minigun light has its' Anode in the rear so as it's pointing down, the Anode is up. The VSS-3 has its' bulb oriented horizontal - the compromise. So these certainly could have been airborn using the compromise orientation. But why the 90 degree head?

The non-90 degree light has a cast alum lens holder that finishes it off in front so the lights were made to be finished off either way - straight or 90 degree. Either end piece will go on either light - the snout and its' mounting flange are the same on both lights. The rotational motor wiring exists in both lights.

I did learn a tid bit today from an acquaintance. He knows someone who worked supplying a few short arc bulbs to a military contractor here in the U.S. many years ago. It was secret at the time. The light was being developed to defeat some type of Radar system. It was heavy in the U.V. output and could be variably pulsed and was approximately 1KW. I don't see any pulsing facilities or components (not that I would necessarily recognize such components) but it is interesting that Marconi Radar Systems business was all about designing and building Radar systems. Who better to develop a Radar defeating device that themselves?

Final coat of Liquid electrical tape applied today. A good 24 hours to dry and maybe tomorrow or Friday might be fire-up eve. Not sure about the beam shots though. Gotta think about how to do it descretely.

Re: 1,000 Watt Military Short Arc Behemoths

Grabbed a quick, down and dirty beam shot out of the garage. Just kind of a "it works" shot. Unfortunately there is no frame of reference beyond the gate. The next surface for light to hit is 4,800 feet away and fog was starting to obscure it. So at this point, I don't know how it looks on typical 350 yrd, 900 yrd and 1,100 yrd targets I usually shoot at. Not much else I can do given the length of my power supply cables. Might try my tired 110 Amp SLA's to see if I can take the setup to the range one night. Kind of looks like a natural gas flame.

It's a 1000 Watt light, give or take. Running about 19.5 Volts and 49 Amps to the bulb, all other components such as fans etc are out of the calculation. So it's currently running at about 955 Watts.

The end of my Cul-de-Sac is just to the left of the beam and I made sure that all neighbors were in for the night and that no lookie-loos were coming before I ran it. Neighbors across the street were aware and promised not to look at the source. Even with all this, I was very nervous about lighting it off.

If you love the sound of a gas turbine winding up, you'd love to hear the start up of the power supply and light cooling fans. The closest I've ever heard! Man, it sounds WAY COOL!

Re: 1,000 Watt Military Short Arc Behemoths

Look'n good bob! Glad to see you got at least one of them fired up!
Seems like a damn bright beam, but is it me or just the photo, that makes it like its weighed heavy to the upper right? Can't wait to see how the distance shots compare! Wtg bud! Congrats

Re: 1,000 Watt Military Short Arc Behemoths

BVH said:

Grabbed a quick, down and dirty beam shot out of the garage. Just kind of a "it works" shot. Unfortunately there is no frame of reference beyond the gate. The next surface for light to hit is 4,800 feet away and fog was starting to obscure it. So at this point, I don't know how it looks on typical 350 yrd, 900 yrd and 1,100 yrd targets I usually shoot at. Not much else I can do given the length of my power supply cables. Might try my tired 110 Amp SLA's to see if I can take the setup to the range one night. Kind of looks like a natural gas flame.


It's a 1000 Watt light, give or take. Running about 19.5 Volts and 49 Amps to the bulb, all other components such as fans etc are out of the calculation. So it's currently running at about 955 Watts.

The end of my Cul-de-Sac is just to the left of the beam and I made sure that all neighbors were in for the night and that no lookie-loos were coming before I ran it. Neighbors across the street were aware and promised not to look at the source. Even with all this, I was very nervous about lighting it off.

If you love the sound of a gas turbine winding up, you'd love to hear the start up of the power supply and light cooling fans. The closest I've ever heard! Man, it sounds WAY COOL!

Click to expand...

Very cool lovecpf
How about a video of the startup process?

Re: 1,000 Watt Military Short Arc Behemoths

Turn the volume WAAAY up!




By the way, the searchlight is not dimmable. The "Dim" knob on the switch box is for dimming the switch box "Shutter Open" and "Lamp On" pilot lamps.

I received 7 cables with the lights. Each cable is sheathed in a fine brass/bronze flexible weave material. I'll bet each cable cost between $300 and $500 to manufacturer.

When warmed up, total Amp draw is about 57 including the fans. My 100 Amp Lorain rectifier acts as though it's not even turned on. There is no Voltage sag at all. 28.0 when idle and 28.0 when powering the load. What a deal at $150! And as a bonus, there is no cooling fan so no useless noise. It has massive heat sinks on the back side.

Re: 1,000 Watt Military Short Arc Behemoths

Thank you very much for the cool video

Thats louder than I though it would be, your description sound about right though

I do think the noise would be somewhat prohibitive when using the light anywhere...

Re: 1,000 Watt Military Short Arc Behemoths

Marconi is part of BAE now. I used to work for them at the Rochester factory (Rochester in Kent, not Rochester in New York). I cant actually say what they made there (official secrets act) but suffice to say they were THROWING OUT loads of cool stuff...I expect they may have had some stuff similar to what you've got there. If only i'd been into lights back then!

Re: 1,000 Watt Military Short Arc Behemoths

Thanks snake. Might you know of anyone who may have worked at the Leicester plant who might know something about these?

Driver your right about the noise being loud for a light. But it sure sounds great and adds to the mystic of the lights. These certainly won't be "casual use" lights with all the equipment needed to run them away from a 240 Volt outlet. I could do it now but it would take my 175 lb, 4.5KW generator, the 85 lb Lorain and its' #4 cables, 30 lbs of hook-up cables, 55 lb power supply and 70 lb light. I'd love to spring for some high Amp Hour, custom 7-cell SLA's but they are way too much money for very occasional use.

Re: 1,000 Watt Military Short Arc Behemoths

What do you do in your spare time? Googling and ebaying on 'prototype searchlight' ?!
Congrats, interesting thing.

Would have thought it was for optical communication..say over the Street of gibralter or over the Berlin wall.
Is the some kind of shutter inside? Or only the oscillating mirror?