>
>-----Original Message-----
>From: Richard <2@mail.vcnet.com>
>To: Steve Thompson <g8gsq@qsl.net>; AMPS <amps@contesting.com>
To: <amps@contesting.com>
>Date: 08 March 2002 23:07
>Subject: Re: [Amps] TenTec Titan 425
>
>
>
>
>>>? The whatever on the anode is 8kV positive or negative. This is
>>>apparently sufficient to attract or repell the negatively charged gold
>>>melt-balls - and change current flow. Typically, I see way less leakage
>>>current with negative 8KV. With air leakage, the current is the same
>>>with either polarity.
>>
>>
>> I should have said ...whatever the metal is on the inside of the anode
>>...... If we have -ve charged gold meltballs, why should they exhibit
>>different repulsion from the gold of the grid compared with the copper(?)
>on
>>the inside of the anode?
>>
>The grid is at 0v. The anode is at +8kV. The meltballs go to the anode.
>When the polarity is reversed, the meltballs seemingly head toward the
>base because current decreases.
>--------------
>Attribution failure
>
? RR
>When the polarity is reversed, won't the meltballs go towards the +ve grid
>and give the same current?
>
? With pos. 5kV on the anode, some of the meltballs apparently stick to
the anode insulator where they form a leakage path. With neg 5kV on the
anode, thanks to like charges repel, the meltballs apparently head
through the grid-cage and fall toward the base. By tapping on the top of
the tube, more meltballs can be dislodged and moved into the base. A
>20:1 reduction in leakage current can be accomplished with this seemingly
shmuckish technique. However, if the tube is inadvertently inverted,
some meltballs move back to the anode insulator and anode-grid leakage
increases substantially.
- The tapping process also dislodges gold meltballs from the strontium
and barium oxide emissive coating on the cathode. Since gold poisons
electron-emission, dislodging gold from the cathode increases emission.
Thus, a tube that was producing low anode-current, may return to normal
emission. (note - gold meltballs are too small to be seen with a
magnifying glass, so I use a 30x microscope to view them)
cheers, Steve
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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