The power supply and spark-gap board…
Pictured above is my completed power supply board. The input filter and safety-gap board sits on top of the neon sign transformer. The small grey box (lower left corner) is the supply junction box and also houses the second mains line filter and MOV. The blue tube is the 25uF power factor correction capacitor. Front center is the main RF earthing bar and on the right is the main spark gap (detailed below).
The main spark gap. The tube is 110mm pvc about 200mm long. The pipes are 15mm x 75mm copper with 0.5mm gaps between each. The bolts sticking out of the top are the variable tapping points for altering the power output of the coil. At present, it runs best at the highest setting but one. At the rear of the tube is the quenching / cooling fan.
I believe this type of gap is named after it’s creator, Richard Quick and are usually just called ‘RQ’ style units.