813 in my vttc...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Brett Miller <brmtesla2@xxxxxxxxx>

All,

Regarding my 813 vttc experiments, I probably ought to
run by the specs one more time, just in case some
folks missed them in my initial 833A vttc first light
post.

Primary Coil:  21 turns 12AWG stranded THHN on a 6"
dia former.

Secondary Coil:  19" winding length 26AWG on a 3.5"
dia former Fo greater than 300 KHz even after topload
to ensure nice swordlike sparks.

Feedback Coil: 25 turns awg 23 enameled magnet wire
(high temp polyester).  Feedback Coil has been slid up
the primary/feedback former until it is about in the
midpoint of the secondary winding.

Tank Cap:  2x 1.1nF 50KV doorknob caps in parallel for
2.2nF

Grid leak resistance:  6K at 50W

Grid leak capacitance:  1.1nF Yish doorknob

Large MOT with no current limiting and doubler (12x
1n5408 diodes for 12kv at 3A).

Filament transformer:  Medium sized Zebra MOT with
secondary hacksawed off and filament winding added
(12AWG stranded) for a bit over 10V.  Actually...it's
running at 11V on the 813 with no power applied.  This
may be important to note, since running higher voltage
on the filament may produce greater emission and
higher overall output from the coil (I'm not worried
about burning up the filament).

...

At first I had used an 18 gauge jumper to attach the
813's heater to the 833A filament socket already on my
vttc base.  This was bad.  I got 6" sparks on the
average.  I soldered some 10 gauge wires onto the 813
socket (which were about 3 inches long) and outfitted
them with crimped on ring lugs.  I then bolted the
ring lugs onto the 833 terminal posts.  As soon as I
went over about 110 volts on the variac I was getting
12" sparks...output had doubled as a result of going
to larger gauge cathode wiring.

Vttc veterans are probably scoffing, but it's a big
lesson for me, and something to keep in mind for
beginners.  Don't wimp out on the wiring for the anode
and cathode on your vttc, it will bottleneck.  I
thought I could jumper just for a test, but if you do
so, the test will be mostly in vain.

-Brett



____________________________________________________________________________________
Do you Yahoo!?
Everyone is raving about the all-new Yahoo! Mail beta.
http://new.mail.yahoo.com