Hi Steve !
Well... according to a red coloured note I found in the
original Eimac box when ordering some 4CX250's many
years ago,- those tubes contained BeO.
According to that note the premises should be immediately
evacuated and Eimac called if a tube seal cracked !!!!
I suspect this was Eimac's way of avoiding possible damage claims,-
but the note stated clearly that the product contained BeO ...
I asked a friend in the industry about this and he told me that BeO
were often used as a combined mount/insulator/heatsink for the G1
and G2 structures in metal/ceramic power tubes.
I do not think it is necessary to evacuate if you break a seal ! Unless
you machine the stuff or treat it in a way that makes BeO powder
or dust I would not be too concerned.
BTW my microwave oven came with some really idiotic warnings...
It did not tell me not to dry my cat in it,- but it came close :-)
***My latest shipment from Eimac with 4CX250's came without the
warning note .. they may have changed internal construction or revised
their policies... ****
Peter
----- Original Message -----
From: "Steve Thompson" <g8gsq@eltac.co.uk>
To: <amps@contesting.com>
Sent: Saturday, November 17, 2007 11:09 PM
Subject: Re: [Amps] more dangers in our shack
> A lot?
>
> The only tube I know of which has BeO in its structure is used in
> the UK Clansman 353 tank radio. This has BeO between the anode and
> a conduction cooling mounting flange. CCS1 and 8873 use a BeO
> block for the cooling path.
>
> BeO can be dangerous, and I play very safe if I break it in a
> transistor, but I believe that prolonged exposure to a specific
> range of particle sizes is needed to lead to lung disease. The
> fumes from incineration are probably more dangerous.
>
> Just for calrification, in a RF power transistor, the BeO is
> between the mounting flange and the leads. The white top cap is
> alumina.
>
> Steve
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