Wireless Set No. 52 Canadian - Project

[David Dunlop]

One other oddity I forgot to mention with these Counters.

If you take a close look at the two sets of photos in Posts 280 and 281, you will notice the gears and drive bushings are all fitted to their respective shafts by taper pins on the Counters used with the Coil, Aerial Tuning No. 2A

On the Counters used in the Sender, these gears and bushings are all mounted by means of Bristo Set Screws, which have been doubled up on each gear, each pair set 90 degrees apart.

David

[David Dunlop]

The next stage of the Sender front panel disassembly has been working on the removal of the Blower assembly from the access door. The first step in this is to remove the COVERS, Metal, Blowers, Electric from the front of the door. This is necessary to gain access to the three machine screw heads of the hardware holding the mount for the blower motor in place.

I found the ¼-Drive Socket Set worked best for this when a universal joint was added between the socket and handle as the upper two nuts holding the COVERS in place are quite close to two of the motor mounts on the inside of the door. Clear lacquer has been used to secure the nuts, but they break free quite easily.

Interesting to find the screen on the front of the cover had a small trim strip of metal folded over its edge. It keeps all the sharp ends of the screen wires out of the way, likely prevents the screen from unravelling and provides a good mounting surface for the 12 spot welds used to secure the screen behind the front lip of the COVERS.

The four posts used to mount the COVERS to the access door are described as:

SCREWS, Spade, 6-32 x 11/16-inch No. C1 with a 0.144-inch dia. hole in the flat end. ZA/CAN 4372

This hole takes a small rivet used to mount the screw to the inside of the rim of the COVERS. The four screws are fitted in a square pattern around the COVERS rim.

Once the COVERS has been removed, one can clearly see the three slotted, round head machine screws holding the Blower Mount in place. The crud on the fan blades is largely just dust with some zinc or cadmium oxide build-up, but it all rubs off rather easily.


David

[David Dunlop]

Removal of this assembly from the Access Door is going to be nice and simple by looks of it.

Only one wire needs to be disconnected, which is the main feed line from the 8-Pin Plug on the back of the Sender running up to feed into the RF Choke L30B (tied in place on top of the board), and the Capacitor C3AF, mounted directly underneath the choke on the bottom of the board.

The entire motor assembly at that point can simply be removed as a unit by removing the three Machine Screws.

David

[David Dunlop]

I was sitting staring at the Sender this morning with a fresh mug of tea, when I noticed a detail about these PLATES I had missed in my earlier Post #274 regarding them. Not that what I noticed provided any answers to the mystery already identified. It just adds to it.

As you will notice in the first photo attached, all five of the PLATES, Stop, No. 1 fitted to the Sender panel are dimensionally identical to each other. Some look a bit wider but that is just dirt accumulation on, and around them. What I did not notice earlier, however, was that the spacing, centre-to-centre for the rivet and set screw on the lone PLATES for the PA TUNE Dial, is a lot shorter than the other four plates to its left.

The PA TUNE PLATES has a centre-to-centre mounting space for its rivet and set screw of 9/16 inch. The other four are all 1 inch centre to centre for the same measurement.

I checked the measurement on the two PLATES on the 52-Set Receiver and, as shown in Photo 2, they are both showing the wider (1 inch) centre-to-centre distance.

Now my curiosity is really peaked! Not only do I not understand why only one PLATES was used for the PA TUNE Dial, with installation for a second PLATES partially abandoned, but now I would love to understand why a different hardware mounting pattern was used for the one lone PA TUNE PLATES.

This is probably boring as hell detail for most of you, but with so little documentation about the design and production of the 52-Set having survived from the Canadian Marconi Company, I thought noting these detail bits here at least preserves the information, and if none of us can figure it all out now, perhaps somebody down the road will.

David

[David Dunlop]

I was able to do a quick unsoldering of the power cable to the BLOWERS Assembly this morning and remove the BLOWERS.

The first photo shows the BLOWERS Assembly still mounted to the Access Door, but free of its power connection to the Sender.

I can see no useful need to remove the BLOWERS from its Mount so shall leave them as an easily serviced unit. In the second photo you can see the free standing (sitting?) BLOWERS with its hardware. The positioning of the hardware is relevant to the three legs of the mount. Notice that there is no lock washer for the hardware used in the upper right mount (viewed from the front of the BLOWERS). That is the mount where the ground connection is made for the BLOWERS with a locking terminal that fits under the hex nut. All hex nuts were clear lacquered in place when installed.

The last photo is an important one. When I was examining the BLOWERS in situ on the Access Door, it looked like the three short posts on the BLOWERS Shock Mount were riveted in place through the rubber bushings, but I was not absolutely certain of that. When I had backed off the three hex nuts securing the mount, the three posts moved with the BLOWERS assembly, but when the BLOWERS was finally free from the Access Door, I gave one of the posts a gentle turn and it pulled free of a metal sleeve fitted inside the rubber bushing. So be careful of these three posts should you ever be removing the BLOWERS from your 52-Set. They could go dancing off somewhere inconvenient if allowed.


David

[David Dunlop]

I was a little concerned about these two KNOBS on the 52-Set Sender.

On the Receiver, these two KNOBS are mounted to the lower front panel assembly by means of lock washers and hex nuts and when the upper front panel is removed, the hardware is easily accessible for removing the KNOBS. Things did not look so promising for the KNOBS on the Sender.

First and foremost, any hex nuts behind the front panel would be totally inaccessible on the Sender. I did reason, however that if the front panel assembly was the last big item to be fitted to the Sender Chassis on the Production Line, when I removed the front panel, I should then be able to the elusive hex nuts to restore the two KNOBS and then remount them. For whatever reason, it looked like when this particular 52-Set was in for major service in 202 Workshop in 1966, somebody did not bother removing the KNOBS and merely over sprayed them, chipped paint, dirt and all, with a new coat of varnish.

Out of shear boredom for the most part, but rationalizing the trip to buy another bag of bird feed, I dropped into the local Peavey Mart on Saturday, and while there discovered a small, 1-1/8 inch diameter flexible inspection mirror. Turned out to be the perfect size to slide into the right side of the chassis to look between the two Flick Mechanisms at the right hand KNOBS hardware with a small flashlight.

Happy Dance! Instead of using hex nuts and lock washers to mount the two KNOBS on the Sender (as per the Receiver), CMC must have realized how difficult they would be to access for any required replacement. Their work around was to spot weld a small rectangle of heavy gauge steel behind the front panel where the KNOBS were to mount, and tap this small bit of metal with a hole to accept the threads on the KNOBS.

A gentle counter clockwise turn of the two KNOBS loosened them and off they unwound. In the photo, you can see the drip ring of varnish that accumulated on the front panel around the base of each KNOB.

One more pair of items off the Disassemble List!

David

[David Dunlop]

A couple of more quick photos.

The first shows the front panel of the Sender with the crud that had accumulated inside the COVERS Assembly, having been cleaned away from the Access Door. Like the two Knobs, the last 202 Workshop overhaul saw the COVERS remain in place and get recovered in a new coat of varnish over existing dirt and paint chips. I had suspected this following a closer examination of the COVERS earlier, when removed from the panel, and a thin varnish ring under the crud on the door confirmed it.

The second photo is of the inside of the Access Door. The CMC Part Number of the door can be seen under a coat of varnish at the lower left bottom edge of the door. I do not yet understand the significance of the large blue "V" Stamp in the lower right corner. I do recall seeing another large single blue letter stamped somewhere else on one of the 52-Set pieces but have not yet tracked it down. In the upper right corner, on the reinforced lip of the door is a round blue CMC Inspection Stamp with the number '700' at the bottom of it. Just above the "V" is a second CMC Inspection Stamp that has been double struck. I can make out a "73?" at this point.

David