>
>Tom Rauch wrote:
>>
>>You need enough capacitance near the screen to absorb the initial spike.
>>Neither a MOV or gas tube will work well by itself. Even a modest
>>overvoltage is too much for regulators. Slow the transient down.
>>
>>Actually, the MOV is a last resort just to protect the socket
>>capacitor...as would be a gas tube.
>
>The MOV or gas tube at the screen terminal is actually the *first* line
>of defense because that is where the arc hits. Tom correctly identifies
>that the screen bypass capacitor in the socket is at least as valuable
>and important as the tube. The tube may survive,
A tube that arced is already a proven leaker.
>but if you blow that
>capacitor, you need a whole new socket.
The last two tetrode amplifiers I built were grid-driven and they had
directly grounded screens. ....... Direct screen grounding is how large
tetrode amps are normally built.
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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