Final Assembly

(The Beginning of The End)

This is it guys! The coil is practically done. Now that we have all of the components ready it was time to do the final assembly and place them all into the control cabinet, wire everything up, connect the two coil stands and perform some final tests. At this stage the coil is actually complete; however, the doesn't mean that the coil is finished, we still need to test and tweak it and fix any problems that arise.

We actually has a small mishap, the voltage and current screens that monitor the primary and aux circuits needed to have isolated power which we weren't informed about. This cause a short circuit of mains voltage crossing through the DC power circuit destroying the screens. New ones have since arrived and been installed, relays now isolate them. 

Once we officially finished the wiring in the control board, wiring and mounting began inside the control cabinet. The MOT stack power supply and voltage doubler were built and installed, the safety gap was correctly spaced and mounted and the charging choke assembly was fitted along with the primary MMC array. All of the latter components were then connected to the other components such as the spark gap and RF chokes with wire and solder. All necessary components were grounded and a new ground lead ran to our grounding rod. Also, a fresh coat of paint was added to the control cabinet.

We also had a problem with inrush current, the large variac was pulling tons of amps and caused our on board breaker to trip. We added a resistance circuit and short circuit switch to fix this.

As it was soon time to test the coil proper, we spent a good amount of time reviewing everything to ensure there was no potential problems that we had overlooked. Upon further inspection, the primary coil was dangerously close to the secondary. To prevent arc overs, we added acrylic tubing around the innermost coil. After doing so we decided it would be a good idea to apply the same principle to close cables inside the control cabinet. Wooden slabs were also inserted to help separate thing inside from crossing.

 We even decided to vacuum out all of the dust and wire cut offs to tidy thing up a bit.

Once the control cabinet wiring was done, we ran the HV cables from the cabinet out to the 2 coil forms and set it all up for preliminary testing.

The coil is done. After everything was set up, over the past few day we ran many tests. Many small problems came up such as bad soldering, broken contacts and power problems. All of these have been fixed now though. 

The aux circuit is officially done and works, the spark gap fans come on and the spark gap motor fires up and spins the disk. Using the tachometer and hall sensor, the disk reaches around 3200RPM before the tachometer cuts out. We were along using half the voltage from the variac at that point. A new tachometer is on order.

The final test ran today. This was the one of main power. We didn't expect it to work first time and our expectations were right. As previously insinuated by the very limited current carrying capacity and previous tests, the diodes lives were short lived and burnt out straight away. This prevented the voltage double from working and thus no arc across the spark gap. New diodes are on order, this time rated for 25kV at 2A.

Until they arrive there is nothing else we can do excluding small alterations and improvements.

The next blog post will be a test with them installed, hopefully then, the coil will have its first light.

Stay tuned, the end is right around the corner!

Next: First Light???