Re: VTTC question

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

Original poster: "Steveh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <steve.g.hall-at-attbi-dot-com>

250TH tubes would work well for a tesla coil. The specs are as follows:
Fillament - 5V 10.5A
Max plate voltage - 4000V
Max plate current - 350mA
Max plate dissipation - 250W
Max grid dissipation - 40W
A 250TH tube can easily put out 750W of power in a class C power oscillator,
possibly up to 1000W if you push it to the limit and have a very efficient
circuit. That said, a pair of 250TH tubes could do the same or a little bit
better than a single 833 tube. You should get sparks in the 21 to 22 inch
range (with two tubes).
If you do build a tesla coil with these tubes, be very careful not to
destroy them. Be sure and use the proper finned heat sink connectors on the
plate and grid. 250TH tubes were only made by a few manufactures and have
been out of production for many years. These beautiful tubes are quite rare
now and are highly sought after by collectors. Also, the plates on these
tubes are made of tantalum and are quite small for a 250 watt tube. They
would melt relatively quickly if overloaded. If you want to build a coil
with rare, unusual tubes, these would be the ticket. If you want to generate
lots of power, I would recommend the 833C tube. These tubes have a huge
graphite plate and are very rugged. Chineese 833A and 833C tubes are easy to
find and can be purchased new for about $100. I just bought a brand new one
on eBay for about $60. They work very well for tesla coils. Good luck!

Steve
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, November 09, 2002 2:50 PM
Subject: VTTC question


 > Original poster: "Gregory Peters by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <s371034-at-student.uq.edu.au>
 >
 > Hello all,
 >
 > Today at a hamfest, I saw several large vacuum tubes, namely:
 >
 > LK250TH
 >
 > These are quite large triodes. Any idea how well these would work in
 > a VTTC? How long a spark?
 >
 >
 > Cheers,
 >
 > Greg.
 >
 >
 >