Wireless Set No. 52 Canadian - Project

[David Dunlop]

The location of this part can be seen in the first photos of Posts #619 and #620, directly below the T1A Transformer.

The Circuit Reference for this resister is ‘R14A’ and it is the Meter Adjustment used for calibrating the Meter. It is reached by means of the long slotted screwdriver in the Tool Kit from directly above, between the Flick Drive Assembly and the Tuning Condenser. The adjusting slot is visible immediately to the left of the Flexible Tuning Drive Coupling, when you look straight down in that location.

It appears to be another ‘in house’ CMC product, with its CMC Part Number stamped into the rear cover of the resistor case, ‘115-294’.


David

[David Dunlop]

This JACKS assembly is oriented vertically in the lower right front corner of the receiver, with Circuit References J2A and J2B.

I have left the SWITCHES, Toggle, DPDT No. C3 (ZA/CAN 4669), circuit reference S4A, still attached for future reference.

The first photo shows the two components more or less oriented as they are on the chassis. Approximately three inches of the lower chassis plate are bent down to form the lowermost front wall of the receiver chassis. The Switches along this three-inch strip all mount directly to the chassis and the lower front receiver panel has large enough cutouts to drop down over the mounted stitches.

The JACKS, Telephone, on the other hand gets installed along with the switches, but is not mounted until the lower receiver panel is in place. External tooth lock washers sit between the front face of the JACKS assembly and the back of the lower receiver chassis plate.

The second photo shows the side of the JACKS that faces to the interior of the chassis: towards its SWITCHES S4A located immediately to the left of the JACKS. The body of the JACKS is cast Bakelite and two slots on the inner face hold the two spring metal contact strips that secure the Phone Plugs when inserted into the JACKS. The retaining hardware for these two springs also serves as the mounting points of the electrical leads to the JACKS.

The last photo shows the side of the JACKS facing to the outside right of the chassis where the mounting hardware for the two contact strips is secured with an internal tooth lock washer and a pair of hex nuts each fitting.



David

[David Dunlop]

This is the last of this type of switch used in the 52-Set Receiver. This is the TONE FILTER Switch, located on the lower left front of the receiver, between the Mode of Operation Switch and the Meter Switch. Its circuit reference is S4C.



David

[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