[TCML] unknown tube...

[BunnyKiller]

Hey Jim...

it is common belief not to touch halogen bulbs due to skin oils, it is 
also not good to touch hi impulse bulbs used for lasers also...but then 
again, both of these types of bulbs are operating in hi temperature 
enviroments and most are under hi pressure... 3 - 10 atmospheres.  The 
actuall arc is normally in contact with the "glass" envelope ( normally 
made from quartz glass, halogen having the tungsten element within 
millimeters of the glass) and knowing that an arc can create excessive 
temperatures ( whe are talking plasma temps), the oils left behind from 
handling can in many cases compromise the general integrity of the 
envelope ( causes tiny hairline fractures in the glass surface which 
leads to an explosive failure). As far as contaminating the envelope of 
a vacuum tube device, you must ask the question of does it lend itself 
to the same heat levels as an arc lamp? Is an arc being formed and is it 
in close proximity to the envelope? With what I do know of vaccum tube 
devices, I would have to say that touching the outer envelope would not 
be detrimental to its life as it would be for say a laser style 
discharge lamp... Im old enough to remember the TV repair man coming to 
the house to replace tubes in the TV and he never cleaned the tubes he 
handled when he replaced them....  and they would glow red when the TV 
was on...  damn Im old....someone would actually come to the house to 
fix the TV!!! 

Scot D



Ed Phillips wrote:

> Hello coilers,
>
> I know it is true that one shalt not touch the glass of a halogen bulb or
> the vacuum will be compromised by the oils in the skin. Is this true in
> general of vacuum tubes?
>
> Jim Mora"
>
>     No and I don't think that's the reason for not touching the 
> envelope of those light bulbs.  The explanation I've heard is that any 
> fingerprints or the like can carbonize and cause local heating which 
> is injurious.  I don't think those things operate under high vacuum 
> conditions anyway.  Anyone know?
>
> Ed
>
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