# Shootout Maxabeam Gen3-85 Watt & CAI Communicator 123 Watt



## BVH (Dec 27, 2011)

Written sometime in June/July 2011…



You might have already read something of this 150 Watt Short Arc military searchlight. If so, you know that the bulb was damaged and the light stopped working. I offered to buy the light knowing its’ condition because I love military lighting products. Before I made an offer, I had to ask myself – “Self, do you think you’ll be able to find a new lamp for this 30+ year-old light?” I answered “maybe” and that’s good enough for me! I figured that even if I was unsuccessful, I’d have fun trying and I’d still have this unique light in my possession. 

As a side note, this device is called a Searchlight/_Communicator_. I don’t remember this being mentioned or it might have been lost when CPF had its’ hiccup early this year. Obviously, one purpose was for use as a handheld long-range visible and infrared searchlight. Purpose number two, and probably the primary purpose was to be used as a personal communicator when used in conjunction with another identical light operated by someone else. Absent from this light is the cylindrical shaped light wave receiver/amplifier that mounted to the top of the light, microphone and earpiece. When connected, the device did two things: 1. It converted a persons’ audible speech into electrical impulses which in-turn, were used to modulate/pulse the light produced by the short arc bulb. 2. The receiver on the light down field received the pulsed light wave and converted it back to audible speech. Two people could voice-communicate with each other at up to approximately 7 miles pretty much as if they were using walkie-talkies. This could be done in both visible and infrared modes.

My quest to get the light going started by tearing it down to see what was going to need repair and/or replacement. Once I knew what needed to be done, I contacted a department director at the CAI, a division of Bourns Inc. company (the original manufacturer) to inquire if a long-time employee might know something of this light and its’ bulb. The director informed me that Goodrich had bought this part of the business from them and forwarded my email to two people there. That avenue ultimately yielded an answer that there was no one there familiar with the light and no info on the bulb. I then web searched short arc bulb mfg’s and came up with a couple of companies that I sent inquiries to about trying to match the bulb. They were helpful in doing research but again, the ultimate yield was nothing. Understandably, large companies have no interest in selling a bulb or two. I then sent the bulb to Dons Bulbs.com who hoards tons of obsolete light bulbs and performs detailed bulb searches if he doesn’t have any. After I had sent the package off, I found Wolfram lighting, a small specialty company that makes short arc lamps. I emailed them and received a reply that they don’t make this type of bulb but that another company they forwarded my email to, might be able to help. I followed up with an email of my own to the new company (Advanced Radiation Corporation - ARC) and received a reply that they, more than likely, could make this bulb. My heart raced! 

I quickly emailed Dons Bulbs and asked him to terminate his search and to mail the bulb to this company. After they received the bulb, they had some technical questions which I tried to answer the best I could. We were talking about bulb dimensions and arc location and it became apparent to me that in order to do this right, I needed to take the light up to them so they could see physically see the bulb and how all the parts worked together to position the bulb in proper focal point of the reflector. Part of the problem was that the Anode base was damaged to the point where it was not possible to know its’ original critical dimensions. 

A tiny bit of Anode electrode connector ribbon sticking out of the quartz. I saw that the Anode base endcap had been ground down and separated from the ribbon








There was a similar problem with the Cathode base adapter but there was barely enough original material to obtain the needed dimensions.

















Luckily, ARC is located within a reasonable driving distance from me.

I arrived at 8:15 and was immediately greeted by John, one of the owners. He ushered me into the offices where I got to talk with Ray, his dad, the founder of the business, now retired (but shows up every day, M-F and works for free). This man probably knows everything there is to know about gas discharge lamps. (This company makes the OEM lamps for Spectrolab’s NightSun and Starburst short arcs and the original stick Maxabeam bulb among hundreds of other bulbs. I got to hold a NightSun bulb! I had sent many macro photos and measurements to them the day before, and believe it or not, they had new bases already made when I got there in preparation for making a new lamp. No order had been placed, no money given, yet they were already working on it! I had expected this to take 2 – 3 weeks to accomplish, but WOW, they were already on it. 

As you can see in the pic above, the Anode end of the original quartz bulb still had about .030” of the electrode sticking out so Ray, the founder said why don’t we go out back in the shop and test the bulb. If it works, just silver solder on the new base, re-pot it and call it a day – NO CHARGE. Well, a couple hours later, I was re-assembling the light with the original working bulb as tested in their test rig! This was WAY more than I had ever expected! I had brought my tools and portable 28 Volt power supply just in-case and that proved to be a good move.

Unfortunately, the light did not fire up. Lots of arc strikes as it should be doing but it did not light off. Well, after having taken up 4 hours of the two owners time and receiving machining services from three of their employees for free, I did not feel it was right to take up any more of their time. I thanked them profusely and headed for home. After all, I knew the bulb worked after their repairs because it tested out fine. 

I got home and started to trouble shoot the problem. In darkness I could see arcing taking place but it was not between the Anode and Cathode tips. It was somewhere further back in the light. I kept trying to ignite it so I could tell where the short was. Surprise! Just before I was ready to stop for the evening, the light started up four different times after about 30 tries. 

I eventually decided that the arcing was occurring from the Anode base to the wall of a large, thick ceramic bushing the bulb Anode base sits in. When I looked very closely at the bulb base, I could see what I thought were arc traces on it. How could the spark jump through the ceramic bushings’ 3/16” wall to ground? I kept Ray and John updated with my troubleshooting and they offered many suggestions and technical info. (I now know the purpose for the tiny wire that wraps around the arc chamber. It’s called the Trigger Wire and in some uses, is electrically connected to the cathode base, then wraps around the arc chamber but obviously does not connect to the Anode. During ignition, High Voltage is present in the wire which Ionizes the Xenon gas in the arc chamber so it can then be ignited when the spark jumps the gap inside the bulb). 

The next morning, unprompted from me, I got a call from Ray and John. Ray told me that the ceramic bushing is most likely Aluminum Oxide and if it’s dirty enough, it could be conducting. The bushing did have quite a bit of metal tracings in it from bulb movement made during the focusing operation. I had tried to clean it the night before but it is one tough piece of material and I could not do much. He said the only two ways to clean it are in a bath Hydrofluoric acid, which is unobtainable by most people or to heat it in an industrial oven to about 1100C. He then offered to clean it for me if I would mail it to him. Again, NO COST! That being done, the light still failed to start but I could still see the arcing taking place. It turns out that the arcing was actually coming from a very loose fitting front/Cathode bulb adapter. (The ground brass adapter in the pic above) I saw this when I took the light apart. There is a small spring between the adapter and the bulb base. Because of the loose adapter fit, the arc was finding its’ way thru the small gauge spring which could not handle the power and was beginning to melt in half. There were arc track marks on the bulb base. Oh well, I thought at the time, I’ll have to wait for the new bulb which will have threaded studs on both ends for a positive fit. At the time, I had no thoughts of buying a lathe so I figured I'd have to go to a local machine shop to get some adapters made. 

ARC suggested that when they make the new bulb, that I have them shorten the arc gap a little to make starting easier and to provide more surface brightness from the bulb with just a bit more power consumption. It will have better throw, too with the smaller light source. A few weeks after my last communication with them, I had decided to buy the lathe so I told them to hold off making anything until my lathe arrived and I set it up. This was early August.

Fast forward to this week… My new PM1236 lathe arrived about 5 weeks ago. It took me a few weeks to get it set up and adjusted. Last week, I horsed around just turning shafts, doing my first threading and some practice boring. Last week, I figured that since I’m still waiting for the new bulb, why not try to make a special adapter for the working bulb I have now. It will be good practice and if it works, I’ll have two working bulb/adapater setups for this old light. I spent a total of about 10 hours making the adapter in the pics below. It doesn’t look like much for 10 hours of work and it would probably take a machinist less than an hour to make, but I’m just learning. There were so many calculations that I needed to nail down in my mind. Bore diameter of the adapter for a very, very light “press fit” over half the length of the old bulb base. OD for the end of the adapter that goes into the split retainer clip/ground contact, OD for the shell since it sits in another larger bore, taper angles, how to make the tapers, remaining wall thickness of the shell – will it be strong enough to support boring down to about a .028” wall thickness, (this because I needed to use my parting tool to cut down the shaft behind the adapter to a very small diameter so I could get in there and create the taper. I should have done the boring first!). What order should I do the different cutting operations in?. All this and trying to insure that the arc gap ends up in the same place as it did with the old adapter.

I’m so pleased that I got all the machining done without destroying the part or any tooling. I had visions of the adapter breaking away from the original shaft material due to forces beyond which it could handle or boring thru the shell because the walls were getting thin. I assembled the light and it works like it should! Ignition is very rapid now with the solid ground contact.

Here’s the Communicator














Here’s how the original bulb mounting parts lay out in the light







Original Cathode adapter loose on bulb base. Original adapters "clipped" onto the rounded base ends and did not fit over the cylindrical part of the base.







Front light window ***'y where the Cathode base adapter is located







The adapter bore and split ring seat







New adapter exterior. My Very First part made on my new lathe!







New adapter interior. The small hole is threaded to 8-32 so I can use a screw to pull the adapter out of the split ring







Question: When parting off, is there a technique to not ending up with a nub needing to be removed?







Just for info: The ballast mounted on the inside of back cover. Two, double layered IC boards.







The Ignitor – located on the back side of the light body, next to the ballast.







The control panel on the back of the light. Forgot to show the focusing knob where the focusing shaft comes thru the center hole. The "blank" is where the audio receiver/transmitter used to connect.







Beamshots:

CAI Communicator 350 Yrds





Maxabeam Gen3 350 Yrds





CAI Communicator 900 Yrds





Maxabeam Gen3 900 Yrds






CAI Left Maxabeam Gen3 right, 350 Yrds









This is a 150 Watt (Input Rated) light. About 123 Watts goes to the bulb. I'm a little disappointed that the 85 Watt Gen3 Maxabeam focuses narrower and throws further. Well, it’s only 1970’s technology. It’s still quite a machine for its time and I love having it.


----------



## mvyrmnd (Dec 28, 2011)

What a story! Those blokes at ARC need to be bought a few beers, I think. Kudos to them and congrats on your light


----------



## ma_sha1 (Dec 28, 2011)

BVH,

Unbelievabe what it took you to get it working again! Bravo! 

This is likely the only light remaining of its kind, even Bob/Dir. of Engineering at Peaks Beam didn't know it existed. 

Were you able to change bulb position to achieve optimal focus? The light originally limited its focus ability & could not go down as tight. The arc is probably still much bigger than the MB bulb so that the increased power wasn't enough to over come the increased arc size.

Congratulations!


----------



## BVH (Dec 28, 2011)

ma_sha1 said:


> BVH,
> 
> Unbelievabe what it took you to get it working again! Bravo!
> 
> ...



Ma, final bulb arc location rearward will be achieved by constructing the new bulb so that the arc gap is .065" more rearward into the reflector. I've accomplished more rearward movement on a temp basis by shimming that amber colored plastic retainer (held in with the 3 screws) back by .060" with tiny washers underneath it. I can now dial the knob such that the hotspot gets to it's smallest size and begins to grow and de-focus if the knob is turned further. The only negative of that is that the silicone O-ring does not seat against the Aluminum Oxide insulator bushing but I don't run it for long periods so it should have no overall negative effect. It made a big difference in reducing the hotspot/narrowing the beam. What I noticed at the 350 mark, is that the hotspot of the Communicator can actually be made a bit smaller than the MB but in doing so, it becomes dimmer. It's difficult to see in the reduced size pics but the beam of the Communicator close to the light consists of two elements that converge much like the beam of the VSS-1 tank light that I used to have. Probably because of the large area taken up by the infrared shield mechanism and the spider across the window. Because this may be a one-of-a-kind makes me enjoy it even more. I enjoy keeping old lights alive.

Mvyrmnd, Father and both sons received 4Sevens Mini123's.


----------



## FRITZHID (Dec 28, 2011)

Congrats Bob on getting this jem working! its a beautiful light and you've done a great job fab'n the new parts, looks great! (time to add this one to your tag line!)


----------



## Echo63 (Dec 28, 2011)

Nice work on getting a rare old light back up and running.

I agree with myvrmnd, the guys at ARC deserve some beers.


----------



## Parker VH (Dec 29, 2011)

Thanks for the great report Bob. Congrats on your lathe purchase. Let the projects begin!!


----------



## Parker VH (Dec 29, 2011)

Bob, Did you have the enhanced output reflector added to your Maxa Beam? I thought you did, but I wasn't sure.


----------



## BVH (Dec 29, 2011)

Parker VH said:


> Bob, Did you have the enhanced output reflector added to your Maxa Beam? I thought you did, but I wasn't sure.



Yes. It's all Gen3 except, Peakbeam says one of their hand-selected bulbs added about 900,000 CP to my specific light versus the OEM Peakbeam bulbs I got off Ebay. With my bulb, it's producing 11,900,000 and with theirs, it was reported as 12,800,000 CP.

EDIT: I'm hoping when I get the new, shorter arc, higher luminance bulb, my throw and brightness will increase. I know I'm losing some throw and brightness now because the Anode electrode has worn unevenly which has most likely increased the arc gap and caused the flame to be non-symmetrical.


----------



## Chicago X (Dec 29, 2011)

What an awesome light, and story to go with.


----------



## DM51 (Dec 30, 2011)

Great stuff! Superb report, excellent photos and beamshots. 

When I started reading and saw that beautiful reflector, I thought the MB was going to be beaten into second place, so it is very interesting to see the result. Marvellous to see a vintage light being brought back to life!


----------



## Sway (Jan 3, 2012)

Most excellent work in getting the communicator up and going Bob! 

I just love reading stuff like this and many cudos to the guys at ARC for their assistance :bow:

Cheers
Kelly


----------



## BVH (Feb 15, 2012)

IlluminatedOne said:


> Great to see it up and running again. Nice to see a peice of short arc history back in working condition.
> 
> It sure would be great to have a pair of those with the audio transmitters and receivers.
> 
> ...



Great find Illuminatedone!! I enjoyed reading his site. And I thought my Communicator was advanced technology for the 60's/70's! WOW, the same technology back in the 40's from a 5 Watt bulb Incan bulb! Amazing!


----------



## Patriot (Feb 15, 2012)

Amazing story about this vintage rebuild BVH! I'm always blown away by your tenacity and resourcefulness when it comes to solving these types project puzzles. Great job with you new lath and machining. I feel kind of silly that I didn't even know this type of light and communication technology existed back then. I was even more impressed to read the link that Illuminatedone posted. I couldn't help but to boggle over the precision and complexity of the tiny parts and intricate machining packed into these devices. It really fits the stereotype of German innovation of that era. 

Back to your build BVH, I was thinking that the Communicator was going to embarrass the Maxabeam. I was surprised at how dominating the Peakbeam was in comparison but like you stated, 30-40 years difference in technology accounts for a lot. I noticed the split beam effect of the communicator right away in your pictures and at first was trying to figure out why I was seeing two beams. Kudos to you for keeping another piece of history running!


----------



## BVH (Feb 15, 2012)

I'm really hoping when I get the new, smaller gap bulb, that it will do better. The Anode tip in the original bulb is not a perfect "V", probably due to the wear of many hours on it. So some distortion of the point of light is taking place, I'd imagine. Smaller gap, better formed electrode and maybe it will be closer or better, who knows. Compared to the MB, the size of the Communicator "center support" so to speak, is huge, hence the appearance of the split beam. It's actually more of a tapered ring/donut beam when you see it in-person. Still, it's fun to have an oldie working again.


----------



## Patriot (Feb 15, 2012)

Yeah, judging from the beamshots, it wasn't only the lack of perfect focus but the overall luminus flux seemed far behind the 85W MB. Given the wattage of the Comm. I expected more lumen output regardless of how tightly if focused. Something tells me that efficiency is being lost. Wouldn't that be amazing if it was all remedied by the new bulb...tighter and brighter! oo:


----------



## BVH (Feb 15, 2012)

ARC says the new bulb should produce around 2800 Lumens. I "think" the Gen3 MB produces 2000'ish? The CAI's reflector is larger but with more loss in the center (may or may not matter) So who knows until I get it and machine the adapters to use it. Excited, I am!


----------



## DM51 (Feb 15, 2012)

Someting I should have done before - I've added this to The BIG Lights thread.


----------



## BVH (Feb 15, 2012)

Thank you DM! Do you ever use the Barn Burner?


----------



## DM51 (Feb 15, 2012)

Yes... if I want to demo some impressive lights, out come the Barn Burner, Polarion PH40 and Maxabeam!


----------



## matthewcyho (Feb 16, 2012)

Nice BeamShot , Bob


----------



## rhodiuman (Feb 17, 2012)

Very nice work, keep the fire burning


----------



## Bill Idaho (Feb 18, 2012)

BVH: 
I might have found another one! The one I found is about the same size, is definitely military, complete, apparently in working order. The housing seems to be a little different as it does not have the ("cooling"?) fins. One minor hiccup though: 
It has a coiled cord (and not very robust I might add) with a relatively small three prong fitting. I have several -make that MANY military radios, receivers, antennas, etc, including all the related cables. As I've stated before, I have a VSS-1 AND a VSS-3 with all of their cables/connectors. I'd like to think (humbly) that I am somewhat familiar with most common military connectors/fittings.
The connector on this hand-held is way smaller than anything I have ever seen before.


----------



## BVH (Feb 18, 2012)

Now Bill....Come on....How could you make that post without pictures! It's almost a crime!!  I need to see it, please post some good close-ups. Does it have the cylindrical modulator attached on top? Have you tried it? After re-reading your post, maybe you found/saw one and it belongs to someone else? If that's the case and you're not interested in it, I sure would be if it's for sale?


----------



## Bill Idaho (Feb 19, 2012)

No, it's not mine, (but POSSIBLY for sale). I have my doubts. (I'll have to convince him he'll never be able to find a power supply, and he may as well sell it to me......hmmmm)

Admittedly, my web-fu is NOT up to posting pictures. I can snap some pic's but I have a hard time wrapping my head around all the "photobucket" stuff. Maybe I can send them as an attachment to your email address?


----------



## BVH (Feb 19, 2012)

Would love to see them. 

Does it have the modulator on top?


----------



## Patriot (Feb 20, 2012)

BVH said:


> Would love to see them. [email protected]




If you're able to and if the lead is good, would love to see the pictures as well.


----------



## BVH (Apr 9, 2012)

Update. Got my new ARC bulb today. I've got to make some base adapters to accommodate the better crafted bulb bases so it will be a while before I get it installed. The best thing is that the great guys at ARC gave it to me for free! Thank You A.R.C.! Pic a little later.


----------

