Assembly Instructions

Unscrew the rear tubular housing from the coupling nut and then unscrew the front tubular housing from the coupling nut. Remove the mu-metal shield (10) from the retainer ring (12) by loosening the nylon locking set screw (11). After insertion of the PMT in the socket, install the mu-metal shield and make sure it sits squarely in the bottom of the socket base (13). WARNING: The mu-metal shield should NEVER be assembled in the base without the plastic insulator ring (09). Electrical shock may result if someone touches the outside housings under such a condition. The plastic insulator ring also serves as a mechanical alignment aid to keep the mu-metal shield centered within the front tubular housing. Tighten the nylon locking set screw but don't over do it and strip the nylon threads in the process. The mu-metal shield has a solid friction fit in the copper ring inside the retainer ring to make good electrical contact. Screw the base assembly, with the PMT and mu-metal shield attached, back into the front tubular housing, up to the half way point of the threads in the coupling nut. The PMT socket and dynode chain assembly (15) is spring loaded (16) so one can see how much compression the light guide will induce on this assembly, thus assuring a good contact with the PMT without the risk of damage to the latter. Insert the collet nut (03) and the inner collet (04) onto the light guide as shown in Figure 5.9. Position the outer collet inside the entrance to the front tubular housing and check that it matches the direction of the cone to that of the outer collet. Smear a thin layer of optical grease on the light guide and insert the latter into the inner collet until it makes contact with the PMT. This can be verified by observing the movement of the socket against the, now slightly compressed, springs. Insert the outer collet into the inner one and screw the collet nut making sure the springs remain slightly compressed in the process. Use the special tool to tighten the collet nut until the light guide cannot be moved in or out. Replace the rear tubular housing by screwing it all the way into the coupling nut. Insert the foam plastic light stop (02) between the collet nut and the light guide. The mechanical assembly is now complete.