This is the first video in a series of 3, on how to get started with the UD3.1b Tesla coil driver, FiberNet and TeslaTerm.

I love you all for the great work!

Great. I'm not saying 1/4 inch is wrong here but a few weeks back I buttoned up
a small coil with primary current of ~200amps and 3/32" copper tubing. Worked great.

One disadvantage of having the connection and wire come out from the top makes
secondary strikes to the primary more likely. Not only does it reduce the primary to
topload distance it also introduces sharp edges rhat encourage flashover.

In my limited experience tesla coils are all about screwing up so be prepared...

Cheers.

I thought that you just wanted the ability to change the output needle position according to some user-adjustable control. For that case, the "John Freau phase shifter" may work because you only need an adjustable phase shift with a 60 Hz frequency. However, if you want to see the needle rotate then you need some small frequency adjustment as others have stated. And as others have stated, some sort of inverter with 120 volt output is probably the most logical way to do it. I have seen "true sine wave" inverters for sale but they aren't cheap. I'm not sure if a conventional PWM (square wave) output inverter will work. You would just have to try one. In either case, you would then need a way to slightly adjust the output frequency of the inverter since they are designed to be fixed at 60 Hz. Depending on the method used to generate the 60 Hz output perhaps you could possibly hack into the circuitry to provide a way to adjust the output frequency slightly. I am not hopeful of that because I think that the output frequency is tied directly to the input frequency.

If the meter will operate properly with a PWM output inverter, you could use a single phase of the 3-phase output of a VFD. These commonly provide a way for the user to adjust the output frequency with a knob, either built-in or externally supplied. 240 volt single phase input VFDs with 240 volt 3-phase output are commonly available. I use one to control my lathe. I can adjust the output frequency with a knob. There may be a 120 volt VFD available but I don't know. If this would work I have seen small cheap Chinese VFDs on E-Bay for less than $100.

Looks great.

I'd wonder about making contact to the primary ring for tuning. From the top you have to get
down into that narrow canyon. From the bottom cutting holes...

Not a criticism just curious...

Cheers.

Yeah that's a good question, what I intend to do is basically make a metal P-clamp into a 90 degree connector that mates to an insulated wire using a 3d printed housing (if that makes any sense). I'll post it after I design it. I was going to drill through the bottom once tuning is established then cover the top. Also the grooves are big enough for 1/4" tubing but I was thinking about trying the 1/8" tubing first which will give me more room to make the insulated connector. It didn't seem to make a big difference in javaTC whether it was 1/8" or 1/4" and considering the relatively small amount of power I'm going to use and the skin effect, I am not convinced 1/8" will be too small but I don't know. I'm trying not to screw this up but this is the first tesla coil I've ever built unless you count the slayer exciter.

Looks great.

I'd wonder about making contact to the primary ring for tuning. From the top you have to get
down into that narrow canyon. From the bottom cutting holes...

Not a criticism just curious...

Cheers.