tubes-- ID ?

From:  Robert W. Stephens [SMTP:rwstephens-at-headwaters-dot-com]
Sent:  Saturday, April 11, 1998 8:29 PM
To:  Tesla List
Subject:  Re: tubes-- ID ?

> From:  DamDeName [SMTP:DamDeName-at-aol-dot-com]
> Sent:  Thursday, April 09, 1998 11:59 PM
> To:  tesla-at-pupman-dot-com
> Subject:  tubes-- ID ?
>  Hi all -- 
>       I need some specs on some tubes----
>  1.   AMPEREX  # 6508  ------------  made in Holland
>  2.    UXL 2000 DK ---- made in Japan -- ( xenon projector lamp , I believe )
>  3.    XBO2000W/hofr--  OSRAM - made in Germany  ( xenon projector lamp ,also)
>     The amperex tube looks like a high power pulse type -- ( hope so ) :-)
> thank you 
>               Sandy


I used to work with xenon projection lamps, and although I can't put 
my hands on my Osram catalogue I can tell you from memory:

The XBO2000W/hofr is a 2000 watt short arc xenon lamp.  It will 
operate at about 28-29 volts DC across the lamp at up to 75 Amps.
the h means horizontal burning is permissible (vertical burning anode 
up, is also possible), the ofr means that the 
grade of pyrex used for the envelope stops short UV making this lamp 
Ozone Free.  Osram are one of the highest quality of xenon arc lamps.
Note that they are under considerable positive pressure when cold 
(about 8-10 atmospheres).  When hot the pressure climbs to ~20 atmospheres.
They should be handled like live hand grenades and shipped with the 
anode up.  They should not be removed from their protective plastic storage
explosion shield until completely installed in the lamphouse.  These 
things are considered lethal if they pop in your face, especially 
while hot.  They are incredible lightsources, but they sure push the 
materials technology to the limit.  I'm not trying to scare you.  Just warn you
of the dangers.  I've personally never had one go pop, but I've heard enough
stories.  They really make a mess of the lamphouse if they decide to go
boom.   Once they have reached their rated hours of operation they 
should be removed from service, even if they appear to be running 
fine.  The inside of the glass grows dark from deposited tungsten and 
this makes them run hotter.  Eventually the pyrex breaks down from 
the extra heat.  I like to put old ones up against a tree and pop it 
with a 22 rifle at a safe distance.  I then save the anode and 
cathode.  The cathode is thoriated tungsten.  The anode is more pure 
tungsten and perfect for spark gap electrodes.

The UXL 2000 DK is a similar lamp by the sounds of it and will 
probably be a 2000 watt lamp.

The power supply for these is similar to the DC supply used for 
carbon arc lamps, but since the xenon lamp electrodes cannot be 
physically brought together to strike the arc, a high voltage, high 
frequency igniter, a spark gap driven Tesla coil in actual fact, is used in series 
with the anode or cathode of the lamp and the DC supply.  About 40-50 kV is 
required to start a 2 kW xenon lamp.  I have some 2 kW ignitors in 
stock if interested. They produce the required 50 kV at about 30 mHz.
The DC supply should have a no-load voltage of 
about 80 volts for these lamps or they won't start reliably, dropping 
to the 28-30 volts once the lamp arc starts.  Ripple current reduces 
lamplife and must be kept below 5%.  The power supply is kind of 

Oh yeah, forgot to mention, these lamps require properly designed 
forced air cooling.  I wouldn't operate one without consulting an 
application guide.  These are available from Osram/Sylvania.  Ask for 
any pamplets they have on Theatre Xenon.  I know one of them is 
called "How to get the most from your Xenon lamp", or something like 

Have fun.

Robert W. Stephens
Lindsay Scientific Co.
RR1 Shelburne, ON Canada L0N-1S5
Tel: 1-519-925-1771   Fax: 
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