Re: Toxic magnetrons?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Jim Lux <jimlux-at-earthlink-dot-net> 

At 04:14 PM 8/29/2003 -0600, you wrote:
>Original poster: G <bog-at-cinci.rr-dot-com>
>High-power magnetrons may contain beryllium in the filament. Not generally 
>an issue in consumer equipment...

Curious... Can you cite a specific magnetron part number or manufacturer 
that uses Be in the filament?


Other than in Sam Goldwasser's microwave oven FAQ, have you seen any 
manufacturer's literature that indicates that any vacuum tube uses Be in 
the filament?  Thoria, yes, other rare earth oxides, yes, particularly in 
"dispenser cathodes".  I did find a single literature reference (1996 IEEE 
International Conference on Plasma Science) to using Be/BeO composites in 
dispenser cathode in an experimental Crossed Field Amplifier (which a 
magnetron is a special case of) for the AEGIS SPY-1 radar.   There are some 
references to using metallic Be in decidedly unusual magnetrons (as used in 
Russian plasma physics labs). There are also some references  (at IVEC 
2000) to Be cathodes in connection with an oxygen reservoir to create a BeO 
film, mostly to say how unsuitable they are and to discuss replacements, so 
they do exist (in those "baby Amplitrons" in the SPS-48 and the 
aforementioned SPY-1D).

The point is that you're really, really unlikely to come across an 
unlabelled tube that has Be in it, notwithstanding the literal truth of 
Sam's statement that "Magnetrons MAY contain Be"  sure enough, some 
magnetron probably does contain it.

There is a good chance that a high power (much higher than consumer 
microwave at 1kW) might have BeO (Beryllia) in it as a mechanical support 
or component.  Most high power tubes do use BeO somewhere. Can't beat that 
real high thermal conductivity and good properties when it gets hot. And 
frankly, BeO is a bigger problem than Be... it's brittle, cracks, and makes 
dust, which can be inhaled.  I'd not just go bashing ceramic vacuum tubes 
or RF transistors with a hammer on the driveway.

The curse of the web....  factual statements (i.e. "High power magnetrons 
with beryllium in the filament") without backup or references.

Why am I ranting???? There are enough legitimate hazards around that you 
should really pay attention to (high voltage,e.g.) rather than agonizing 
about the possibility of Berylliosis from a magnetron.  The original 
statement was that there was a "highly toxic pink bead", and I believe that 
the original poster made the comment based on reading from the web from 
FAQs like Sam's.  By such means do inaccurate data propagate (like "skin 
effect prevents TC RF from penetrating human skin", which is repeated over 
and over, although demonstrably false.)

If the original poster has independent knowlege of the toxicity of oven 
magnetron components, then they should say so.


>cya,
>Gregory
>
>>Can you elaborate on the "highly toxic pink bead" you referred to?
>>
>>What is the actual material the pink bead is made of?
>>
>>Where is it located in the magnetron?
>>
>>Are you referring to a microwave oven magnetron, or a high power radar
>>magnetron?
>>
>>Regards,
>>Scott Hanson
>--
>"Without ZIM, I am lost."
>GeekID#-1229
>http://thegeekgroup-dot-org
>