Introduction & Tube 833A

Hello.  This is my first post to the list so maybe I should 
introduce myself first? I'm quite young, only 16 years old and
I live in Finland. I have been reading the list for more than 
a year now and received lots of valuable information, so 
thanks everyone who has posted to the list =)

During the past 1 years I have built (with the help from my friend) 
two coils and tried to build a tube driven TC but it didn't work very well.

The sparks from my first coil were only about two inches long and
my current coil puts out sparks about 20" long but I'm expecting
to get more in future. I'll probably post the details of my coil later 
and see if anyone of you have some tips for making it better...

But now to the main reason for this post, the tube 833a...
I could get few unused 833a:s for cheap, only about 40usd piece,
or at least I think that it is quite cheap price for that tube (correct
me if I'm wrong?).  According to what I know about 833a it should 
be suitable for TC use, and now I would like to know that will it work
and if it will work then how well will it perform in tube driven tesla
In the past I have bought so much parts that I haven't been able to 
use after all, so now I want to be sure that I don't buy something I can't 
use. And I would also like to get specifications for that tube because I 
don't have the exact data.

Thanks in advance,