>
>measures wrote:
>>
>>>
>>>measures wrote:
>>>>The grid protection circuits I am talking about are those that provide no
>>>>protection because the transistor that interrupts has too low a current
>>>>rating and it shorts during a glitch -- thereby affording no protection.
>>>>
>>>Failure of that transistor to survive a glitch/arc/parastic/flash-
>>>over/whatever is a simple DC design fault that can be cured by a 10K
>>>resistor.
>>>
>>A 10k-ohm resistor can prevent C-E shorts due to excessive collector
>>current?
>>
>>>I don't think that's a good reason to remove grid current protection for
>>>normal operation.
>>
>>Replacing a shorted transistor with a fuse-R is hardly removing
>>protection. Shorted transistors afford no protection because they can
>>not turn off.
>
>We may be talking about different transistors. Let's start again.
>
>Where in the circuit is the transistor that you say burns out in a
>glitch?
In series with the grid current meter shunt. This transistor must open
to stop the flow of excessive grid current. If the transistor has too
much current, it C-E shorts.
>
>Why do you believe that it should be removed, if that also involves
>disabling grid current protection in normal operation?
Grid current protection is disabled by the C-E shorted transistor. By
replacing the shorted transistor with a fuse or fuse resistor, protection
is restored.
>
end
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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