More Single 833A Info

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Cameron B. Prince" <cplists@xxxxxxxxxx>

Hey guys,

I was finally able to work on the VTTC again tonight and I got together some
of that info you requested. I also made some new observations and confirmed
some other things.

1) The baffle or guard I had on top of the primary is not needed (depending
on #2) See the photo I took tonight:

http://www.teslauniverse.com/members/cprince/images/vttc/DSC00119.JPG

2) The grid coil MUST be wound the opposite direction of primary coil. The
upper turn MUST go to the grid and the lower to the grid leak components. I
am sure the connection of the primary has an impact on this also. In my
setup, the lower turn goes to the plate. Others say that you simply swap the
grid connections if the coil fails to oscillate. I think I've proven it's
more in depth than that. If I reverse the grid coil, my coil runs, but has
constant arching from the secondary to the grid. I believe the direction may
be running the grid out of phase preventing the arcs.

3) Someone asked for plate current values. I tried to connect a meter
between ground and the center tap of the filament transformer like I've seen
in some schematics and the meter went ballistic as soon as I turned on the
staccato controller, but before the variac was brought up. Is this the
correct way to connect a meter to measure plate current and/or could I need
a resistor on my meter? It is a Simpson 1257 0-1DCA Plate Current meter.

In the meantime, I used my clamp meter as you can see here:

http://www.teslauniverse.com/members/cprince/images/vttc/DSC00110.JPG

The meter showed about 260mA at the highest I saw it.

4) Another question I received was regarding how hot the tube ran. Here's a
picture of it taken tonight:

http://www.teslauniverse.com/members/cprince/images/vttc/DSC00120.JPG


Here are a few photos that make up the cabinet I built for the system. This
is a prototype out of scrap wood. I'm going to build something nicer later.
You can see the modular design I'm experimenting with here:

http://www.teslauniverse.com/members/cprince/images/vttc/DSC00100.JPG
http://www.teslauniverse.com/members/cprince/images/vttc/DSC00101.JPG
http://www.teslauniverse.com/members/cprince/images/vttc/DSC00102.JPG


Here are the specs of the various components that make up the system:

PRIMARY COIL

      Form: 11" x 6 1/2" O.D. (5 15/16" I.D.)
   Winding: 30t 12AWG 600V stranded starting 1" from bottom - 5 1/8" up form
Inductance: 116.3 uH total Q 4.04 @ 1 kHz

http://www.teslauniverse.com/members/cprince/images/vttc/DSC00107.JPG
http://www.teslauniverse.com/members/cprince/images/vttc/DSC00108.JPG


SECONDARY COIL

      Form: 17" x 3 1/2" O.D. (3 1/4" I.D.)
   Winding: 16" winding length 28AWG starting 1" from bottom
Inductance: 21.08 mH Q 1.93 @ 1 kHz
Resistance: 334.6 Ohms
Res. Freq.: 419 kHz - 365 kHz w/ torroid
 Electrode: 4" 1/4x20 all thread 3 1/2" extending above end cap sharpened

http://www.teslauniverse.com/members/cprince/images/vttc/DSC00109.JPG


GRID COIL

      Form: 6.25" I.D. - plastic garage sale sign glued to form ring
   Winding: 22t 24AWG 4 1/2" above highest primary turn
Inductance: 167 uH Q .969 @ 1 kHz

http://www.teslauniverse.com/members/cprince/images/vttc/DSC00105.JPG
http://www.teslauniverse.com/members/cprince/images/vttc/DSC00106.JPG


TORROID

          Total Width: 5 7/8"
Cross-Sectional Width: 1 5/8"


TANK CAPACITOR (4nF & 3nF in series - 80kV each)

   Capacitance: 2.4 nF .003 dissipation
Voltage Rating: 160kV


I'm going to play with capacitor values in the grid circuit hopefully
tomorrow night and see if I can further optimize it.

Feel free to drop me any additional questions you may have.

Thanks,
Cameron