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Re: Big Tiode

Subject:  Re: Big Tiode
  Date:   Sun, 18 May 1997 10:06:14 +1000
  From:   Ralph Down <rjdown-at-fan-dot-net.au>
    To:   Tesla List <tesla-at-pupman-dot-com>


>> Hi All,
>> I went to a local Hamfest last weekend and scored a large triode tube
>> (valve).  It is a Philips TB 4/1250
>> about 4 1/2" diameter and 6" tall with a very substantial anode.  I have
>> tried searching on the web for info on this tube, but so far no luck.
>> Does anyone have any data on this tube? - anode voltage, heater voltage,
>> wattage, pin out etc?

>> Any help on Tube Tesla coils would be most welcome.
>> Regards
>> Ralph Down

>> 
>> 
>Ralph,
>
>That tube sounds like a tetrode with 1250 watts plate dissipation 
>rating.  
>Your 0.001 mfd mica cap should be O.K. for your tank cap.  
>Perhaps John Freau can be of more help on this than I.
>
>Good luck, and nice score!
>
>rwstephens
>
>
>
Thanks for the info
I have had a bit more of a look through the glass envelope and done some
tests with a multimeter.
It has a 5 pin base.  Three pins appear connected together by a flat
plate
at the bottom of the glass envelope and the centre of this plate has a
cylindrical tube about 1/2" diam mesh which extends upwards inside the
anode
which is about 1 1/4" diam and connected to a terminal on top of the
envelope.
I surmise that these three common pins are the grid connection and the
other
2 must be a directly heated cathode.
So it looks like a triode with directly heated cathode.
I am going to guess that the heater voltage is 4 volts (TB 4/1250)
I have been told that B signifies a triode
I'm not sure what T indicates (maybe Transmitter Tube)
The 1250 is probably either anode voltage or power rating.

Can anyone help with a schematic diagram for a Tube Tesla using the
above
tube, a .001 7kv mica cap and a 2.5kv microwave oven trannie?

There is not much discussion about Tesla coiling on this list recently,
maybe this will get us all back on topic a bit!

Thanks again 
Ralph Down
Today is the tomorrow you worried about yesterday....... and everything
is O.K.