MTK 446 electronic timer: mounting

Model 446.2002

MTK timer mounting

The timer consists of:

The overall size is 40mm long, 26mm wide and 12mm thick. The total weight, including wiring is 9.3 g. The timer is mounted to the inside wall of the fuselage pod by a single bolt that screws into the rear of the connector unit. This is threaded for an M2 screw. Due to the depth of this hole only a short screw should be used. A length of 3 or 4 mm is recommended.

Model 446.2004

MTK timer mounting

The timer consists of a single circuit board, measuring 42mm long, 21mm wide and 17 mm high overall. The total weight, including wiring, is 7.3 g.

It is mounted to the inside wall of the fuselage pod by a single bolt that screws into the white mounting block, which is threaded for an M2 screw. This screw is supplied with the timer. There is a 1.5mm insulating stand-off on the underside of the circuit board to make sufficient clearance behind the board for solder connections and surface mount components on the back of the double sided circuit board.

Replacing a model 446.2002 timer by a model 446.2004 unit

Some fiddling may be needed to fit a model 446.2004 into the space occupied by the earlier model because it is 2mm longer and 5 mm thicker. In addition, the mounting screw is closer to the top edge of the unit than it was on the earlier model despite it being 5mm narrower.

The timer did drop straight into my 2003 vintage M&K short model but could not be fitted parallel to the bottom of the fuselage. Instead its front end had to be canted up to clear the top battery retainer; if the timer had been installed directly above this retainer rather than to its rear this substitution could not have been made without extensive surgery to the front end's interior.