Re: 811 tube coil

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

Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>

Steve: as I don't know how to send from my new scanner I'll have to use
words. My circuit is a tickler coil oscilator not a taped coil hartly like
yours. It is quite compact with a 3"to 2" cone secondary 6.5" long wound
with 400T of  #32 wire. The primary is 4" OD plate coil # 16 wire tapped
every second turn 34T starting 1" above the base. with a 3/4' space and 50T
#24 wire grid coil above that. The plate coil is tuned with a 500Pf 6Kv
capacitor. The grid coil is not tuned, but has .004 uf  3Kv capacitor to
ground at the bias connection. The other side of the grid coil goes direct
to the grid with no other connections. The power transformer is a 1200v
shunted with .004uf  3Kv capacitor . one lead to the plate coil with the
plate coil then to the plate. All in series. The tube acting as its own
rectifier. The second plate transformer lead is connected to a 5K ohm
reostat in series with a 5K 25W resistor to ground. The reostat being the
grid bias control. The reostat transformer connection also goes to the grid
coil capacitor connection. The fillament is supplied with a 6.3V 10A CT
transformer with the CT to ground. Each transformer has a seperate switch so
fillament can be turned on then the plate supply. The secondaty is grounded
at the bace and has an electric fence insulator on the top with a brass bolt
to make connections. 400 turns dosent give streamer voltages, but provides
200kv to do research. When this was built 2Kv solid state diodes didnt exist
so the tube is the rectifier and oscilator. The coil form is a varnished
paper cone about 10 layers thick with an open brass tape ring at the top to
prevent racing arcs. No toroid. While it is compact it has done a lot of
real work powering research projects  from linier excellerators, X-ray ,
microwave , to  lasers. Its to good to retire with over 50 years on the same
tube. Yes I have a spare tube in a box marked " Victory, save paper" All
ground connections are earth ground connections as no 3 wire power existed.
     Robert  H  

> From: "Tesla list" <tesla-at-pupman-dot-com>
> Date: Sat, 29 Jun 2002 22:13:20 -0600
> To: tesla-at-pupman-dot-com
> Subject: Re: 811 tube coil
> Resent-From: tesla-at-pupman-dot-com
> Resent-Date: Sat, 29 Jun 2002 22:18:59 -0600
> 
> 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
> 
> 
> 
> 
>