Re: 811 tube coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Steven Ward by way of Terry Fritz <twftesla-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>

Robert,
Is there any way that you could give me a diagram of your connections that 
you described?  Ive gotten this coil to work with poor results, it 
oscillates but only puts out a small 1/4" arc.  I need all of the help i can 
get.  You say that this may hurt the tube?  The site claims that it will run 
it at less than its max ICAS ratings, im confused?  So if you could just 
send me a diagram, that would help a lot, thanks.

Steve Ward.


>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: 811 tube coil
>Date: Sat, 29 Jun 2002 12:54:29 -0600
>
>Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><rheidlebaugh-at-zialink-dot-com>
>
>Steve: for a tube to work you must supply + voltage to the plate and ground
>return to the cathode /fillament. A reverse bias or - voltage is applied to
>the grid to controle current through the tube. A tube is a normaly on
>devise. A transistor is normaly off and must be forward biased to turn it
>on.
>      Your schematic shows B+ voltage to the ground and plate via the coil,
>but no - voltage to the filament/cathode. There is - 2500v applied to the
>control grid via the diode, but not to the fillament/cathode. You are
>missing a connection and a resistor, probibly at the R to fillament with a
>5K or so resistor connecting L3/R junction to the grid. The high wattage
>resistor should go to the fillament not the grid. I do not know what is 
>ment
>by the term " sputter mode" of opperation  as this is not a normal tube 
>term
>. Sputter mode is usualy a term used in vacuum deposition and would refer 
>in
>a tube to distruction by excess current.
>     I hope this helps. your curcuit uses a - supply voltage to make the 
>coil
>safer. My coil uses + voltage and no safe way to touch any part of the
>primary. My secondary is grounded to earth ground. My 811 coil was made in
>the early 1950's and with high use is still working well.
>    Robert  H