833A Tube Coil

From:  Pete [SMTP:casius-at-cyberserv.co.za]
Sent:  Thursday, May 28, 1998 12:49 PM
To:  tesla-at-pupman-dot-com
Subject:  833A Tube Coil

Hi to all interested,

As you know, I have recently built a T-Coil using two 833A tubes. I have
been getting +/-200mm discharges with 1600VAC HT supply from an old
re-wound micsro wave oven transformer. Tonight I got daring and fished
out an old DC supply (2800 volts). The supply was from and old two tube
813 grounded grid linear amplifier. Actually the linear is still in
operation. Use it with my CB radio when DX'ing. Gives 600 watts PEP.
The Coil would NOT fire up on DC (Don't know why). The anodes glowed
very orange but nothing happened. So I used the AC voltage at 2000VAC.
This transformer is quite large and the chances of current limiting is
slim.  The T-Coil shot out a discharge of +/-300mm with 2000VAC.  There
was all sorts of funny noises coming from some where, like high pitched
noises. I did not leave it on too long to find out what or where the
noises where coming from. It was actually a little scary -- Ha Ha. I
shudder to think what will happen with the full voltage rating of the
833's (4000 Volts). I can say that a microwave oven transformer is
definitely current limiting and seriously retards output when using 833A
tubes.  This particular microwave transformer is rated at +/-800Watts.
Actually I need to improve my earth. All I have is a piece of twin flex
going to a earth rod 3 foot into the ground.
Will keep you posted when I try the system again. Need a beer now. For
those who may frown " I don't play with T-Coils when I have had a beer
or two".
I have scanned the schematic. It is available as a jpeg file for anyone
interested. The same schematic also works with 812 and 8005 triodes -
tried and tested.

Regards to all