A CAD representation of the finished coil: ("The Phoenix")
Proposed Coupling Adjustment
(Circled in red)
Despite using a long drill I still needed to drill in from each end.
Drilling the Acrylic legs for the threaded rod
The method employed for the 4 sliding trays of 216 capacitors (101nF - 12 strings of 18 in series) was to simply mill slots into four of the Acrylic rods that support the upper level. The trays themselves are 0.197 inches [5mm] thick and the milled slots that retain the shelves are 0.25 inch deep and wide. Anymore depth would have weakened the support rod as the central hole down the centre is 0.314 inches [8mm].
Sliding MMC Trays
The aluminium and brass mounting on the base of the secondary has a central threaded boss (circled in blue) that screws down onto the copper threaded rod (shown below, also circled blue).
This allows the outer surface of the secondary's mounting plate (circled red) to engage against a matching Aluminium surface on the lower part. As the secondary is rotated it then screws itself down and locks tightly, so no movement is possible.
Although most likely not needed, the lower mating surface has a slot cut into it in case it acted as shorted turn.
The base of the secondary is just a normal flange that doubles up as both a mounting point and also the secondary's lower connection to earth.
Screwing the secondary down......
...... until it's fully home and tight.
The secondary is now in place and locked tight against the bottom mating surface.
This is necessary if you wish to use a big toroid, and also the rigidity allows the coil to be moved in situ without having to take the toroid off.
The eventual idea is to have copper bars (shown as yellow above) forming most of the tank circuit.
The basic layout of the SRSG board (Tufnol) takes shape.
Here you can see where the copper busbar has to pass underneath the SRSG motor mounting.
The oblong depression (right side) milled into the base board is to provide clearance for the bottom of the 12" rotor.
(I wish to keep the coil as low as possible to avoid ceiling strikes - things are very tight!)
Wiring CircuitThe individual trays of capacitors for the MMC will each terminate onto the two vertical busbars.One of these bars for space reasons, has had to be routed underneath the main SRSG motor as seen above.
The Finished SRSG
The two upright brass pillars to the bottom left, will hold the horned safety gap. The HT input connections are the two round brass terminals (middle & bottom right). The tall copper rod (rear right) will go through into the top level and will have one end of the primary tap connected to it. While the copper bar running under the motor will go to the MMC.