TCBA Volume 10 - Issue 1
Page 8 of 18
833 Tesla Coil
by
John C. Wiesner
31 Haystack Road
Clifton Park, NY 12065
The 833 type transmitting tube makes an impressive Tesla coil. The tube will withstand a great deal of plate voltage. Mounting the tube may be difficult because of the unique socket used. To overcome the problem, an 11" X 6" aluminum plate was used. A bend was formed 1" in making an L-shaped plate for mounting. This plate can be screwed to the 14" X 18" baseboard. At least 6" should be provided between the secondary coil and the aluminum plate to prevent arc-overs. The primary is wound on a 6" sonotube 6 1/4" high after applying several coats of shellack. The board contains the primary and secondary coils, tube fliament transformer, tuning caps, and bias resistor. The plate supply is contained in a separate box with the power transformer, 20 ampere powerstat, ampere meter, plate main switch and inrush eliminator relay and resistor. The coil is capable of 17" to 22" discharges. When the coil is running the tube will glow a dull orange color.
Parts List
| V1 | 833 RCA transmitting tube |
|---|---|
| TR1 | 10 volt, 10 ampere filament transformer |
| C2 | (2) 500 picofarad mica capacitors in parallel |
| R1 | 5K, 40 watt resistor |
| C1 | .003 mica capacitor (5 kv) |
| C3 | .007 and .002 mica capacitors in parallel (12 kv) |
| C4 | .004 6 KV transmitting mica capacitor |
| L1 | 20 turns of #6 AWG (PVC) close wound on bottom of 6" sonotube. |
| L2 | 19 turns #18 AWG (PVC) wire close wound on top of 6" sonotube (grid coil) |
| L3 | #28 formvar wire wound on 3 1/4" X 33" plastic pipe. |
- PL Pilot Lamp 120 VAC.
- F1 3 AG. 30 AMP. fuse
- SW1 20 AMP. S.P.S.T. switch
- R1 10 ohm 10 watt W.W. resistor
- RL1 120 VAC. 20 AMP. relay
- M1 0 - 50 AMP, AC. AMP. meter
- T1 Plate transformer 3KV. 300 MA.
- Variac or powerstat 0 - 135' VAC. 20 AMP.
The power supply should be capable of deliverying 0-3 kv at 1/2 amp or better.