The boiling point of anything in a vacuum is lower, but I do not know
how much lower it is for gold. In any case, it would still be above
the melting point of 1063ºC.
cheers, Bill
On Apr 7, 2005, at 10:58 AM, Bill Fuqua wrote:
> What is the boiling point of molten gold in vacuum? I assume it is
> lower in vacuum as with any liquid in a vacuum.
> It may be even more complex than that!
>
> 73
> Bill wa4lav
>
> At 10:11 AM 4/7/2005 -0700, R.Measures wrote:
>
>> On Apr 7, 2005, at 3:26 AM, Ian White G3SEK wrote:
>>
>> > R. Measures wrote:
>> >>> No, I'm simply saying that the Eimac tube guys that I knew and
>> worked
>> >>> with said a lot of what passes for "truth" is a bunch of nonsense.
>> >>> In their experience, every case of "parasitic problems" in 8877
>> amps
>> >>> could be resolved by properly grounding the grid
>> >>
>> >> Did the 8877 design team use improper grid-grounding that resulted
>> in
>> >> the "oscillation condition" they observed that caused gold to
>> >> evaporate
>> >> from the grid of the DUT?
>> >>
>> > That seems to be conflating two different stories, on the basis of
>> > information from an individual Eimac employee which the company
>> > subsequently said was incorrect.
>>
>> Eimac's Reid Brandon told Paul Pagel, the *QST* Technical Topics
>> Editor, that Mr. Willis B. Foote was not authorized to release the
>> information on the finding about gold-sputtering in the 8877 during
>> testing at Eimac.
>> >
>> > The "oscillation condition" in question was not a VHF parasitic as
>> we
>> > know it,
>>
>> Agreed since the pattern of gold-evaporation indicates that the RF
>> current was in the UHF region.
>>
>> > but can only arise in extremely large tubes that are big enough
>> > to have their own internal VHF resonances.
>>
>> It's obviously not VHF. Since the resonance of a 3-500Z's grid
>> measures c. 90MHz, my guess is that an 8877's grid probably resonates
>> above 600MHz when it is grounded by an Eimac grid-grounding collet.
>> *Has anyone ever measured the grid resonance of an 8877? - (my dipper
>> craps out at 300MHz)
>> >
>> > What causes gold evaporation is overheating - that much seems
>> obvious.
>> > What caused the overheating in any particular case is entirely open
>> to
>> > question.
>>
>> The grid's base metal is Mo (molybdenum), which melts at 2617ºC. The
>> grid is plated with Au (gold), which boils at 2966ºC. If the entire
>> grid structure was overheated, why isn't the Mo melted in tubes with
>> Au
>> boiling-blisters?
>>
>> >
>> >
>> > --
>> > 73 from Ian G3SEK
>> >
>> >
>>
>> Richard L. Measures, AG6K, 805.386.3734. www.somis.org
>>
>> _______________________________________________
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>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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