>On Thursday 27 November 2003 06:26, R. Measures wrote:
>snip
>> >>
>> >> ** When I see gold meltballs through a microscope, I see no barium
>> >> oxide or strontium oxide.
>> >
>> >I'd be surprised if it was there in large enough lumps to see.
>>
>> ** I can see their spherical shape only with 30 - 50 X magnification.
>> Otherwise, they look like yellowish dust. [see Fig 24 on my Web site].
>> I can see the cathode coating, but none of it appears to be on the
>> meltballs.
>> -- ¿Why would strontium oxide and barium oxide be attracted to a
>> positive charge.?
>
>I think they don't need to be. If something delivers enough energy to spray
>melted gold from the grid everywhere, I reckon that it's highly likely that
>some cathode material gets sprayed around as well, onto the grid and
>into/onto the gold balls.
** Could be, however, strontium and barium oxides are definitely
visable, and saw none other than on the cathode.
>If I remember my valve theory correctly, that can
>deliver the 'rectifier' effect and also account for the change in breakdown
>voltage if the gold balls are dislodged.
** Most of the gold meltballs I see are not lodged, they're loose and
free to move around.
>>
>> >Do you see the effect once the balls are out of the tube?
>>
>> ** I have no means of unsoldering the ceramic-metal seals in order to
>> remove the contaminant. The most successful thing I have tried so far is
>> moving the gold meltballs down into the base by tapping.
>
>Sorry - I meant do the gold balls themselves show a tendency to be attracted
>to a +ve voltage when removed in the same way as when they are inside the
>tube?
** Good question. Next time I open a gold-sputtered 8877, I'll conduct
this experiment. My guess is that the presense of air molecules will not
make a difference.
>
>I've been trying with aluminium dust and 20kV, but I haven't yet seen any
>sign of metal particles being attracted either way.
>
** One would think that aluminum would behave similarly, although,
unlike gold, it's outer electron shell is not chock full.
cheers, Steve
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