[Amps] BeO in tubes

[jeremy-ca]

The original RCA 8072/8121/8122 had no screen grid support which resulted in 
heat distortion bending it into the plate and ZAP. Around late 1966 ceramic 
spacers were used; Ive no idea if any BeO was used but National Radio 8122 
warranty failures were returned to RCA for evaluation. That resulted in the 
final fix in 1967-8.

Carl
KM1H


----- Original Message ----- 
From: "Steve Thompson" <g8gsq at eltac.co.uk>
To: <amps at contesting.com>
Sent: Sunday, November 18, 2007 3:57 AM
Subject: Re: [Amps] more dangers in our shack


> Nils Petter Pedersen wrote:
>> 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 !!!!
> Interesting. In the 4CX250s I've opened up, I don't recall seeing
> any ceramic in the grid support structures - but these would have
> been 60/70s date codes. As you say, maybe the original design was
> different.
>
> Steve
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