Wireless Set No. 52 Canadian - Project

[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

[David Dunlop]

By far the easiest items to remove so far in this project.

With the BLOWERS off the Door Assembly, I was able to get a fingertip up under the top lip of the panel and jamb the hex nuts up against the back of the front panel. It felt like both hex nuts were only on the Screw-Eye shanks about one nut thickness up. A careful counter clockwise turn of the Screw-Eye and each unfastened smoothly.

These two bits had to come out because they pass through both the front panel and the front upper angle of the chassis frame assembly. Now both tagged and bagged.

David

[David Dunlop]

I was initially thinking I would be able to simply unscrew the antenna feed line from the centre rear terminal of this SOCKETS Assembly and it would lift off with the front panel assembly. Closer inspection eventually proved ’no such luck’.

Of the three machine screws securing the Sockets Assembly to the front panel of the Sender, only the lower left one is mounted directly to the front panel. My recent inspection mirror purchase proved useful once again, as when I took a closer look at the other two sets of hardware behind the front panel, I realized both those corners of the chassis frame had also been reinforced with steel gussets similar to the ones evident in the second photo. Fortunately, there is enough clearance behind the front panel to reach all three hex nuts with my ¼ drive socket set.

The challenge is going to be releasing, and removing the 3/8-inch hex nut on the centre terminal on the back of the SOCKETS Assembly. There is no play whatsoever in the heavy duty solid wire feed to the terminal connector held in place by that hex nut and the terminal connector itself is angled downward, reducing the swing one can get with a small wrench. It’s shaping up to be one of those fifth of a turn, flip the wrench, fifth of a turn kind of tasks.

David

[David Dunlop]

It was a bit of a slow process last night to get the SOCKETS, Antenna assembly off the front panel, but I am sure glad the Sender is resting safely on its back for this work. Gravity definitely works in ones favour when removing hardware. Especially when so much of it turns out to be plated brass and you have no hope of securing, or retrieving it, with a magnet. I have only had one part get away on me and it simply fell down to the back of the chassis onto the work desk.

As expected with this SOCKETS, I had to start on the centre rear terminal post with a small 3’8 inch spanner from the right hand side and work the retaining hex nut loose a couple of turns. The locking ring terminal on the end of the antenna feed wire fits between two small flat washers and then the hex nut was applied to tighten everything down.

Once the hex nut was loose, I switched to my ¼ drive 3/8-inch socket with no handle. There is simply no room to use one. I was able to place it over the hex nut and hold it there with one fingertip of my left hand, coming in from the top of the chassis. I could then reach in from the right side of the chassis with thumb and index finger of my right hand to slowly turn the socket. When the hex nut came free of the centre post, it simply dropped inside the socket and the flat washer rested on the outer lip. I could then place the socket down on the phenolic board behind the SOCKETS, Antenna and slide it to the right side of the chassis for removal. A pair of small needle nose pliers was then used to gently move the antenna feed wire and terminal off the post and the inner flat washer just dropped onto the phenolic board where I could retrieve it with a fingertip.

The three sets of hardware that actually mount the SOCKETS, Antenna to the front panel of the Sender are held in place with 5/16-inch hex nuts. There is enough space behind the front panel to access them with the appropriate socket on a quarter drive handle, but not much room to swing the handle. The solution was to hold the socket in place and use a screwdriver to undo the machine screws from the front of the SOCKETS. As soon as the screws loosened, I found I could easily unscrew them and pull them out. The hex nuts and small lock washers simply fell back into the 5/16-inch socket. Interestingly enough, only the mounting hardware in the lower left section of the SOCKETS still had their original lock washers (external star style). The other two must have disappeared when the Sender was overhauled.

Down to just a handful of things to release from the front panel now and then it should be just a pile of screws to undo to release the front panel from the chassis assembly.

David