Difficult mechanical parts
The upper and lower lecher plate are pressed to each other using brass M3 bolds and nuts, insulated by teflon.
The diameter of these insulators is 16 mm, the diameter of the inner ring 10 mm. Total thickness is 4 mm, equally devided between the outer and inner ring (each 2 mm thickness). The thickness of the inner ring is critical because it must fit smoothly in the upper lecher plate.
The HT feed-through is made of teflon as well.
The diamensions are :
Overall diameter : 35 mm. Diameter of 1st ring : 20 mm. Diameter of 2nd ring : 10 mm.
The thickness of ring one and two is 1.5 mm. (both the cabinetplating as well as the brass ht decoupling capacitor plate have a thickness of 1.5 mm). The Thickness of the outer ring is approx. 7 mm and not critical. In the center a 3 mm hole is drilled to allow connection between the ht connector side and the ht capacitor.
This picture gives a close (but fuzzy) look of the ht capacitor side. The 2nd ring can be seen with the 3 mm bold in the middle. A ring of 12 mm diameter and 3 mm hole is inserted first, followed by a soldering joint (with rf coil connected), a washer and finally a 3 mm nut.
The tube connectors are made of brass. The dimensions are 10 * 15 * 9 mm. The hole has a diameter of 9 mm. A M5 bold is used to fasten the connector .
Only one side is theaded. The other side is drilled to 5.1 mm to allow the M5 bold to pass without any friction.