Wireless Set No. 52 Canadian - Project

[David Dunlop]

The full Nomenclature for this component is, SWITCHES, Rotary Disc, SP, 12-Position, 2-Bank, No. C1, and its circuit reference is S3A. It is more commonly known as the ‘Meter Switch’.


David

[David Dunlop]

The full name for this switch is, SWITCHES, Rotary Disc, 2-Pole, 4-Position, 3-Bank, No. C1 ZA/CAN 4207 and its circuit reference in the 52-Set receiver is S2A. It is the ‘Mode of Operation’ Switch located in the extreme lower left front of the receiver.

This switch sits very low in the chassis, which in the case of this receiver was its undoing. Somebody put the receiver down on a workbench, or other surface, at one point without checking to be sure the surface was clear. The result, if you look closely, is that the middle switch contact wafer was shattered.

These switches are designed to be repairable and a large surviving chunk of the 2nd to 4th Echelon Maintenance Manual is devoted in detail on how to do just that. However, one needs spare wafers in order to affect those repairs and the work required is substantial. Hence, this receiver became my parts receiver.


David

[David Dunlop]

I covered off the improvements to these DRIVES that CMC made when I was restoring the Sender last year. You can definitely feel the difference in weight between these assemblies and the ones in the Wireless Set No. 19 once they are free from the chassis. Better quality parts, higher machining standards and more reinforcement would have gone a long way in reducing the physical wear which resulted in sloppy tuning stability.

And it makes sense when you think about it. The intent of these DRIVES was to allow the Operator to pre-set two different communication frequencies – typically a day and a night frequency, so these drives had the potential of being swung back and forth, stop to stop, at least twice a day. No wonder one of the frequent complaints CMC got from Operators was the loss of ability for the Drives to reliably move to frequency repeatedly, over time.

The frame of these Drives is slightly thicker than on the 19-Set Drives and you can clearly see the solid, bronze alloy triangular blocks CMC used to stiffen the top outer mounting corners. On the 19-Set Drives, these corners were simply created by bending the frame sheet metal over in these areas.


David

[David Dunlop]

This Couplings connects the shaft at the back of the DRIVES assembly to the shaft at the front of the Tuning Capacitor, directly behind the Drives in the chassis.

At first glance, it looks very much like a simple coil spring assembly, but in fact; it is a thin sheet steel bellows construction. Note there is no ‘coil’ present, just a parallel set of ‘rings’.

A collar is fitted at each end and each collar has three 8-32 Grub Screws set 90 degrees apart to secure the Couplings to both shafts it connects. These bellows remind me of the much larger ones found in fancy aneroid clock work barometers from days gone by, only they were typically fashioned of copper or brass, back when scientific instruments were works of art.

Interestingly, when I removed this coupling, I marked the two shafts to see where the Coupling actually was mounted. I am glad I did. Nearly 5/8-inch of shaft was under the Coupling at the DRIVES end but with less than 3/16-inch under the Tuning Capacitor shaft end, the grub screws were barely hanging on. Something to be wary of if I am ever servicing one of these parts again, down the road.


David

[David Dunlop]

This is quite an impressive wiring harness when you finally see it out of the 52-Set Receiver chassis. The perimeter rectangle for it in the photograph is 16 inches by 24 inches, and it would have been a very interesting workstation on the production line to watch in action.

I wonder how many of these harness looms would have been assembled in any given work shift?


David

[David Dunlop]

This is the only other free standing wiring harness in the 52-Set Receiver. In the photo, it sits within a 9-inch square.

It is found on the lower left front of the chassis, connecting the A.F. GAIN, NOISE LIMITER IN/OUT and HET. TONE Switches to their relevant circuits on the back and bottom of the chassis.


David

[David Dunlop]

This particular switch in the 52-Set Receiver wins the award for the longest switch shaft.

Its location on the underside of the chassis can be seen in the first photos of both Post #619 and Post #620 .The terminal wafer assembly on the switch is located at the back of the lower chassis, supported in place by a mounting plate that forms a part of the frame for the switch. The holes in the lower front of the chassis and lower front panel plate support the front end of the shaft. Total length of the shaft is 9-1/4 inches.

This is the SHARP FLAT Switch in the receiver circuits.


David