SV: [AMPS] SB-220 Glitch Resistor ???

[measures]

>
>Ian Roberts wrote:
>>
>>measures wrote:
>>> The negative end of the capacitor stack is limited to a couple of volts
>>> above gnd potential due to use of glitch diodes in the metering
>>> circuitry.  The logical place for a glitch resistor is in the positive > 
HV 
>>lead.
>>
>>Presumably there are two possible places to insert the resistor: in the
>>HT a.c. lead right out of the transformer, thus protecting everything
>>including the bridge rectifier and caps, 
>
>No - the problem we're trying to protect against is not a surge into the
>caps (a step start protects against that) but a surge *out* of the caps,
>triggered by the tube going almost short-circuit. 
>
Indeed.  The mystery is that following a big bang, a grid/fil. shorted 
3-500Z most often show normal leakage on a high-pot (0 - 10uA). .   

>The main source of danger to the tube is the energy stored in the caps.
>All this energy can be dumped into the tube unless there's something
>else to absorb it. The basic information is in Eimac App Note #17 [*]
>
>.....
end

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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