On 7/25/06 at 6:08 AM R L Measures wrote:
>On Jul 24, 2006, at 9:03 PM, Will Matney wrote:
>
>> Keith,
>>
>> Excessive grid current did, either from being over driven, or an
>> arc from a gassy tube.
>
>Will M.: Could an unloaded condition cause excessive grid current?
Sure, there's others. I only said two quickly off the top of my head.
>>
>> Best,
>>
>> Will
>>
>> *********** REPLY SEPARATOR ***********
>>
>> On 7/24/06 at 10:28 PM Keith Dutson wrote:
>>
>>> I am not talking about AFTER the fuse blows. What current CAUSED
>>> it to
>>> blow?
>>>
>>> Thanks.
>>>
>>> Keith
>>>
>>> -----Original Message-----
>>> From: amps-bounces@contesting.com [mailto:amps-
>>> bounces@contesting.com] On
>>> Behalf Of Will Matney
>>> Sent: Monday, July 24, 2006 9:33 PM
>>> To: amps@contesting.com
>>> Subject: Re: [Amps] "Tubes 201" - How Vacuum Tubes Really Work
>>>
>>> Keith,
>>>
>>> Since it's loose from ground, and no corcuit can be made, it hangs in
>>> space,
>>> and can only be acted upon by the electron flow from the cathode.
>>> In this
>>> case, if the grid is slightly more positive, it will accept some
>>> electrons
>>> thus bringing it to 0 volts or slightly negative to ground. This
>>> is called
>>> coming into equilibrium or equalling out. If the tube is not slightly
>>> positive, it will not accept any electrons, and the electron flow
>>> will be
>>> opposed by the grid. Terman, and I think the author of Tubes 201
>>> discuss
>>> this. In any case, the grid can never be made positive by these
>>> actions
>>> taking place.
>>>
>>> Earlier, when Rich mentioned about grids, I thought he meant a grid
>>> becoming
>>> positive. Bill posted what he meant which is correct and the same
>>> as above.
>>> I privately told Rich of this, and am sorry I questioned him, it
>>> was a
>>> mis-understanding. We actually were meaning the same thing at the
>>> time.
>>> Rich
>>> like me does not believe a grid can become positive by being
>>> bombarded by
>>> electrons. Even if a grid gets to the point of emitting electrons
>>> from
>>> being
>>> hot, they are replaced by the electron flow from the cathode. By
>>> reading
>>> some other texts, none of those do either.
>>>
>>> Best,
>>>
>>> Will
>>>
>>> *********** REPLY SEPARATOR ***********
>>>
>>> On 7/24/06 at 9:15 PM Keith Dutson wrote:
>>>
>>>> I am totally lost on this excessive grid current discussion. If
>>>> there
>>>> is a resistor or fuse tied between the grid and chassis and it
>>>> blows,
>>>> the grid obviously has a potential above or below ground. Which
>>>> is it?
>>>> Can it be either depending on the fault?
>>>>
>>>> 73, Keith NM5G
>>> [snip]
>>>
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>>
>>
>>
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>
>R L MEASURES, AG6K. 805-386-3734
>r@somis.org
Best,
Will
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