Building the Super 833C Audio Modulated Tesla Coil


This is a dual 833C push-pull low level audio modulated Tesla Coil with a 100 watt mos-fet RF amplifier feeding the fixed bias 833C grids through a tuned phasing transformer. Due to deviation from convention, it was decided to build this Tesla Coil in modular rack mount form. Currently in the design and prototype stages, the "Audio Tesla 833C" will feature some serious cutting edge "old school" technology to the "Nth" degree! Featured below are pictures of the progress to date...more pictures and comments will be added as we move forward with this project! 


The Plate Supply 


High Voltage DC Plate Power Supply Rack, Construction and Testing
(Click on pictures to enlarge)

Calibrated Panel Meters-01.gif (150200 bytes) Building 5kv Resistor Divider.gif (179943 bytes) Front Panel-01 .gif (139829 bytes) Testing MOT's Efficiency.gif (206060 bytes) Chassis Layout Top-02.gif (195564 bytes)

833C PS-01.gif (165472 bytes)

833C PS-02.gif (206374 bytes) 833C PS-03.gif (175791 bytes) 833C PS-06.gif (181285 bytes) 833C PS-07.gif (148315 bytes) 833C-PS-09.gif (172209 bytes) 833C PS-05.gif (201758 bytes)


The Oscillator / Modulator 


RF Oscillator / Mixer / Audio Modulator Rack

Audio Tesla front view-01.gif (30284 bytes) Audio Tesla back view-01.gif (59352 bytes) 833 modulator-osc board top.gif (250794 bytes) 833 modulator-osc board bottom.gif (271464 bytes) 150khz AM carrier (2V  P-P) audio input at 1khz (5V output).gif (186400 bytes) 150khz AM carrier 50 percent (1V P-P) modulated with 1khz.gif (191722 bytes)
150khz mixer output (3V P-P) with 1V P-P input.gif (198526 bytes) 150khz mixer output with 1V P-P audio input at 1khz.gif (189817 bytes) 150khz mixer output with 2V  P-P audio input at 1khz (5V output).gif (199795 bytes)      


The Grid Drive Amplifier


100 Watt GE MOSFET PLC Amplifier Rack
Frequency Range:  30 ~ 450khz
Can you say "grid drive" ?

    100W PLC AMP-01.gif (160403 bytes) 100W PLC AMP-02.gif (151250 bytes)    


The Grid Bias Supply

Current Limiting Grid Bias Supply Module for Class AB1 Push-Pull Operation

  Beta-1 Bias Supply-01.gif (173961 bytes) Beta-1 Bias Supply-02.gif (155072 bytes) Beta-1 Supply-03.gif (145738 bytes) Beta-1 Supply-04.gif (166103 bytes)  

The Main RF Deck (Tank Circuit)


Note: At this time, the RF deck has not been completed. Quite a bit of research and testing has led me in the following directions:

  • A pair of 833's mounted on a custom G-10 base

  • A flat pancake primary coil; center tapped for push-pull

  • An MMC ceramic doorknob cap-bank tested over 45 minutes at full power with a conventional 12kv/60ma table top Tesla Coil! (Pictures shown)-no heating or frequency drift observed! (There are 100 of these in series / parallel configuration)

  • High quality VLF plate chokes used 

833C Custom Socket-01.gif (208751 bytes) 833C Custom Socket-02.gif (193402 bytes) 833C Pancake Primary Tank Coil-01 .gif (200318 bytes) Ceramic Doorknob Caps-01.gif (165216 bytes) Ceramic Doorknob Caps-02.gif (176451 bytes) Ceramic Doorknob Caps-03.gif (175527 bytes)
Ceramic Doorknob Caps-04.gif (225771 bytes) Ceramic Doorknob MMC-02.gif (132368 bytes) Ceramic Doorknob MMC-03.gif (113797 bytes) Table Top SGTC with low ESR oil cap-01 .gif (204027 bytes) Table Top SGTC with low ESR oil cap-02.gif (191653 bytes) Table Top SGTC with ceramic doorknob MMC-01.gif (211257 bytes)
Table Top SGTC with ceramic doorknob MMC-02.gif (172199 bytes) 833-01 copy.gif (94185 bytes)