Wireless Set No. 52 Canadian - Project

[David Dunlop]

This last bit of activity was more of an in depth study than actual physical work. I shall attempt that work tomorrow morning when my head is clear.

I was suspicious some time ago that the Power Selector Switch for MED, LOW and HIGH Power that is mounted directly above the LOCKS, Panel, looked very much like the Selector Switch on the front of the Canadian Wireless Set No. 19 Mk III Supply Unit No. 2. I took a look through the Parts Manuals for both sets this evening and indeed it is: SWITCHES, Toggle, 4-pole, 3-position ZA/CAN 0178.

What struck me as odd when I got my first live look at the 52-Set Sender, was the fact the SWITCHES, Toggle was set so far back from the rear side of the front panel. Only about half of the toggle lever actually sticks out from the panel. Eventually all cylinders started firing and I realized two key things. First, space was needed behind the panel for the lock slide to move up and block the toggle lever from reaching its lowermost, HIGH, power position. Second, the front mounting plate on the SWITCHES, Toggle was designed for a flush fit behind a wireless panel. Point One does not allow this, nor does the fact the LOCKS, Panel occupies the position where the lower mounting screw for the SWITCHES, Toggle would go on the Sender front panel. The work around for this by the Canadian Marconi Company Engineers is rather interesting.

A set of three cylindrical spacers was employed, along with a small, rectangular adapter plate, thereby keeping the switch and the lock unmodified.

In the last photo you can see two long spacers closest to the camera at the bottom of the Sender. These allow the two mounting screws for the lock to pass down and through the adapter plate. Between these two spacers you can see the thin line of the bottom edge of the mounting plate for the switch, with the square lock nut spot welded to it. Normally, the lower mounting screw for the switch would come in from the front of the plate and into the square nut. In this case, the mounting screw comes in through the adapter plate at the back and then into the square nut.

In the background and to the right of the lower right spacer, you can see the smaller spacer that is used for the upper mounting hole of the switch assembly. The upper spacer is shorter than the lower two to keep a constant gap between the rear of the Sender front panel and the switch mounting plate. It will be an interesting exercise getting that shorter upper spacer back in place when it comes time for reassembly.


David