[Amps] Arc distance and plasma

[PA3DUV]

Bill Clinton saw a purple glow AND arcs without inhaling!
Cheers, Dick
PA3DUV

----- Original Message ----- 
From: "Will Matney" <craxd1 at verizon.net>
To: "Steven Cook" <sccook1 at cox.net>; <amps at contesting.com>
Sent: Saturday, July 29, 2006 2:03 AM
Subject: Re: [Amps] Arc distance and plasma


> Steve,
>
> Keep in mind that there's a difference in the gas ionized you see as a 
> purple glow and that of an arc. However, these ions go in the opposite 
> direction of electrons in a tube, and strike the cathode which can damage 
> it. They also start to neutralize the space charge which causes anode 
> current to rise until you have a snowball effect, and the tube can 
> eventually burn up from the high current. This can go on until the cathode 
> can't emit any more electrons and the tube is said to saturate. This is 
> where you'd see a white hot anode and the glass actually getting hot 
> enough to melt.
>
> It's according to how much a tube has went soft (gassy) as to where any 
> getter can clean it up. The gas has to be absorbed by the getter material, 
> and the getter has to be so that it will absorb all gasses in the tube. If 
> the glow is still in the tube after it has set and baked for a while, or 
> baked several times, I'd venture to say it never will. What will happen is 
> that the cathode emmision will start to eventually drop off from being 
> damaged from the ions striking it. This can also cause material from the 
> cathode to be deposited on the control grid thereby damaging it that much 
> more.
>
> Best,
>
> Will
>
> *********** REPLY SEPARATOR  ***********
>
> On 7/28/06 at 4:34 PM Steven Cook wrote:
>
>>Tom, et al.,
>>
>>The 3-500Z's in my TL-922 both exhibit a purple "plasma" above the top of
>>the plate inside the glass envelope.  The intensity seems to change with
>>plate voltage (CW vs. SSB) setting.  Also with frequency.  Does not seem
>>to
>>affect tube function -- output power about 1300W with 100W input.
>>
>>Is this due to gas inside the tube.  Will it eventually getter out?  Does
>>the presence of this gas have a deleterious effect on the tube life
>>expectancy?
>>
>>Thanks in advance...
>>
>>Steve (((WG7K)))
>>
>>----- Original Message ----- 
>>From: "Tom W8JI" <w8ji at w8ji.com>
>>To: <amps at contesting.com>
>>Sent: Friday, July 28, 2006 7:51 AM
>>Subject: [Amps] Arc distance and plasma
>>
>>
>>> Rather than claim I can look at a tube and magically tell
>>> what happened years ago with my magnifying glass,  I thought
>>> I would add a picture of a 3-500Z under RF plasma
>>> conditions.
>>>
>>> The photos clearly show then concentration of plasma during
>>> a hard fault.
>>>
>>> http://www.w8ji.com/fault_protection.htm
>>>
>>> Enjoy.
>>>
>>> 73 Tom
>>>
>>>
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>>
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>
>
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