Amen, couldn't have said it better!
Will
*********** REPLY SEPARATOR ***********
On 7/24/06 at 3:16 PM R L Measures wrote:
>On Jul 24, 2006, at 9:46 AM, Will Matney wrote:
>
>> On 7/24/06 at 6:25 AM R L Measures wrote:
>>
>>> On Jul 23, 2006, at 10:40 PM, Peter Chadwick wrote:
>>>
>>>> Rich said:
>>>>
>>>>> I autopsy tubes, and I have no yet seen an arc mark in a kaput tube
>>>> with a good vacuum.<
>>>>
>>>> It's sad that G6JP is no longer alive. He spent his entire working
>>>> life doing tube manufacture and applications at the M-O valve
>>>> company, and he said that flashovers weren't uncommon.
>>>
>>> Surely, and those valves that had leaky seals and flashed over, did
>>> not pass final test, landed in the recycling bin, and never saw
>>> daylight.
>>>> There's also the articles in the Journal of the IEE. My father in
>>>> law tells me that they had flashovers in continously pumped tubes
>>>> at the QRO point to point stations he worked at -although the
>>>> biggest problem was when someone with greasy fingers touched the
>>>> grid during re-assembly. That meant that they had a lot of pumping
>>>> to do before the valve really got hard.
>>>>
>>>> So Mr. Measures, the fact you've never seen what you take to be
>>>> marks of a flashover in a tube with good vacuum doesn't mean that
>>>> it doesn't occur.
>>> Agreed. However, there's presently a faint smell of specious
>>> reasoning in the air.
>>>> But, of course, proving (or disproving) a negative is not easy, so
>>>> either party can sit back in the warm glow of satisfaction that
>>>> really, they're the ones who are right!
>>>
>>> Are Au and Mo notable emitters?
>>> Can the grid of a tube with a hard vacuum reach high temperatures if
>>> no current is passing through it?
>>> If zirconium has to be at 1400ºC (Terman) in order to absorb oxygen
>>> and nitrogen, how can a 3-500Z's anode getter air molecules?
>>
>>
>> One needs to study how tubes are constructed to see what may
>> happen. The metals used in them were picked
>> over their high heat qualities (wouldn't melt). The plating had to
>> do with emission of electrons.
>>
>> Yes, I seen a reference earlier about the 3-500Z having a getter of
>> zirconium. For it to work, it's optimum temp is
>> 1400 deg C and is what it's ran at in this application.
>
>Indeed
>
>> In that case, the anode would be white hot (the welding color of
>> steel). There's some other problems with this too, but I won't go
>> into them here (IE Hydrogen gas).
>
>Not a minor consideration.
>
>> If one actually
>> wanted to make this work, it looks like a tantulum anode would have
>> been a better choice.
>
>Better but definitely not cheaper.
>>
>>
>>>
>>> Editorial -- As I see it, the proponents of the floating grid
>>> catastrophe theorem have a conflict between reality and what they
>>> wish reality to be.
>>
>>
>> The theory is what has me bothered in that, if I read them right,
>> think a grid could become positive from an arc.
>
>But that would require gas inside the tube.
>
>> Also, in the ways a grid could become positive. A good read of the
>> book, Radio Engineers Handbook, by Terman will straighten out all
>> the mis-conceptions. Actually, Tubes 201 follows right along with it.
>
>The idea of a grid going positive when it is being struck by
>electrons is pretty wacko.
>>
>
>R L MEASURES, AG6K. 805-386-3734
>r@somis.org
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