[AMPS] HV fuses

Wed, 22 Jul 1998 15:30:36 -0700

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Rich Measures said:

>A correctly sized "glitch" resistor does not need to be replaced after
an 
>"event".  A HV fuse may not prevent gold-sputtering damage to the grid
of 
>the tube from VHF parasites.  {see photos in September 1990, QST}

>Limiting peak current discharge current is quite probably more
important, 
>and a fuse  isn't fast enuff. 

Yes I think the fuse cannot be fast enough.  However, I am begining to
believe that the amount of damage sustained by an internal flashover
(i.e. gold sputtering) can be lessened by the addition of a HV fuse.
Just for clarification, my reference to the word "flashover" is an
electric arc
thru free space from the high voltage DC line to a lower potential bus.
Internal, external, or whatever,  due to gas, parasitics, foreign
particles or any other reason.  I think repeated flashovers cause an
accumulated damage that can eventually kill the tube.  The lesser the
amount of energy passed by each event, the better the going gets in the
long term.  

73's  alex samson ke6vkj

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<P><FONT COLOR=3D"#000000" SIZE=3D2 FACE=3D"Arial">Rich Measures =
said:</FONT>
</P>

<P><FONT COLOR=3D"#000000" SIZE=3D2 FACE=3D"Arial">&gt;A correctly =
sized &quot;glitch&quot; resistor does not need to be replaced after an =
</FONT>
<BR><FONT COLOR=3D"#000000" SIZE=3D2 =
FACE=3D"Arial">&gt;&quot;event&quot;.&nbsp; A HV fuse may not prevent =
gold-sputtering damage to the grid of </FONT>
<BR><FONT COLOR=3D"#000000" SIZE=3D2 FACE=3D"Arial">&gt;the tube from =
VHF parasites.&nbsp; {see photos in September 1990, QST}</FONT>
</P>

&gt;Limiting peak =
current discharge current is quite probably more important, 
 &gt;and a =
fuse&nbsp; isn't fast enuff.

Yes I think the fuse cannot be fast =
enough.&nbsp; However, I am begining to believe that the amount of =
damage sustained by an internal flashover (i.e. gold sputtering) can be =
lessened by the addition of a HV fuse. Just for clarification, my =
reference to the word &quot;flashover&quot; is an electric =
arc

<P><FONT SIZE=3D2 FACE=3D"Arial">thru free space from the high voltage =
DC line to a lower potential bus.&nbsp; Internal, external, or =
whatever,&nbsp; due to gas, parasitics, foreign particles or any other =
reason.&nbsp; I think repeated flashovers cause an accumulated damage =
that can eventually kill the tube.&nbsp; The lesser the amount of =
energy passed by each event, the better the going gets in the long =
term.&nbsp; </FONT></P>

<P><FONT SIZE=3D2 FACE=3D"Arial">73's&nbsp; alex samson ke6vkj</FONT>
</P>

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