Wireless Set No. 52 Canadian - Project

[David Dunlop]

The first thing I noticed once I had successfully removed the Cases, Metal C1 from the Supply Unit was a small piece of manila sheet sitting near the back of the tray the Cases rests in, with one side of the manila heavily varnished. The piece of manila is 1-3/4 inch x 2.0 inches. As I was lifting it out of the tray, I spotted a small machine screw sitting in the right, rearmost depression of four stamped into the floor of the tray, in the back half of it. These four depressions form legs, which are spot-welded to the chassis frame of the Supply Unit to secure the tray in place. This screw is a 6-32 x 3/8-inch machine screw. As I was removing it, I spotted straight away that it had come from the right rear end of the tray assembly. The back part of this tray is stamped from a thicker piece of sheet steel and forms the mounting bracket for the brown phenolic plate the holds the three Banana Sockets that accept the corresponding three Banana Plug Power Connectors from the Receiver Vibrator Supply. The sockets are designed as a loose fit on the phenolic board to allow them to easily line up with the plugs when the Vibrator Supply is slid into the Supply Unit and locked in place.

There was no sign of the hex nut or internal tooth lock washer for the loose 6-32 machine screw, and I do not recall ever finding them in the Carriers No. 4. The washer fits under the head of the screw at the front of the tray assembly, but the only way I can see to get the hex nut installed is to slide it in place in a thin was wrench, like those used for working in ignition timing points. Access is completely hidden by the right rear Supply Unit chassis angle. That ought to be fun.

Turned out the manila sheet came from the upper left side corner of the Cases, Metal C1 as seen in the photo I posted previously. It was varnished in place there to prevent any possible shorting contact between the Cases and the Negative Low Tension Brush Holder assembly of High Power Rotary Transformer MG-2A, when the Cases, Metal is in place.

Photo 1 shows the manila sheet and machine screw as found.

Photo 2 is a shot looking directly down the tray assembly from the front of the Supply Unit. It is a pretty good view of the rear phenolic panel holding the three Banana Plug Sockets and you can see the hole on the rear right end where the machine screw fell out. Also, on the tray floor at the very back you can just see the shadow in the dust where the manila sheet was resting, and the four, stamped depressions/feet for the tray can be made out just forward from that shadow.

The final Photo shows the Negative Low Tension Brush Holder of the HP Rotary Transformer, which would be at risk of shorting without the manila sheet on the left side of the Cases, Metal C1. And also in this photo is a good view of the modification to the resister terminal I mentioned earlier, where it had to be wrapped in electrical tape to better insulate it.

David

[David Dunlop]

This simple little part is similar in purpose, though slightly larger than the plates spot-welded into the upper rear sections of the Carriers No. 4 and the Cases, Remote Receiver. They all ensure adequate ground is maintained with the component chassis mounted inside each compartment.

There is probably the additional benefit for this particular Plates in the Supply Unit as it would also ensure the normally loose fitting Cases, Metal C1 that protects and shields the Receiver Vibrator Supply stays quiet and in place.

Space is extremely limited inside the Supply Unit, so as much access as possible needs to be available for servicing. Directly above where this Plates needs to be mounted on the mid-level shelf sits S-11A, the Dynamotor Input On/Off Switch relay. Canadian Marconi used the front two mounting screws for S-11A to mount the Plates. Metal Spring on the underside of the shelf. This means the open front end of the Plates now covers the rear two sets of S-11A mounting hardware, but everything is still accessible for servicing. That would not have been the case if the Plates had been spot welded in place.

In the photo, you will see a small BA screw sitting roughly between the two Plates mounting pan head screws, and to the left. I will refer back to this screw later.


David

[David Dunlop]

The mid-level shelf plays into this saga at this point so I thought I would start there with a photo of the three components mounted to it. While taking this photo, I noticed through the lens, the trace of part numbers along the face of the shelf, directly below the middle and rear components. A check of the photos Jerry Proctor posted of the 52-Set Supply Unit on his website confirmed these numbers should have been there, along with similar numbers stamped onto the side of the front component and the one directly above the middle one. Large black Roman Font with a heavy overcoat of varnish. All these had been very carefully cleaned away. Why, I wonder.

From left to right, these three components on the shelf are:

L28A, the AF Choke (Smoothing Filter) for the MG1A LP Rotary Transformer.

L26A, the RF Choke (Smoothing Filter) for the MG1A LP Rotary Transformer.

S11A, the Dynamotor Input On/Off Switch relay again.

The second photo goes back to the underside and the shelf again and the visible hardware. Note the small BA screw securing the L26A RF Choke above it. This screw, and two others in the entire Supply Unit, are the only ones I can find that still retain their factory original internal toothed Shakeproof washers. Virtually every other Shakeproof washer has been replaced with much larger thickness external toothed washers. I checked both editions of the Parts Listings for the 52-Set and these heavy-duty external toothed washers are not listed at all. They do not show up in any of the other 52-Set components either.

One might think that is no big concern, but take a look at the third photo today. I have slid the Cases, Metal C1 for the Receiver Vibrator Supply back onto its tray in the Supply unit, carefully levelled it and slid it in as far as it can go. It hits the front left hex nut securing the large L28A AF Choke on the shelf above and stops dead! That external toothed lock washer is far too thick. If you look carefully at the hole in the hex nut, you can see the end of the machine screw is set back in the threads of the hex nut. It is not flush with the face of the nut. In fact, the setback is suspiciously similar in depth as the amount of space needed for the Cases to clear the hardware completely. The only way you can get the Cases to go all the way down its tray is to apply a lot of downward force on it to flex the front section of the tray down far enough to get the leading upper edge of the Cases under the hex nut. As soon as you release that downward force, the Cases is stuck and the only way to get it all the way into the Supply Unit is to block the front of it with a piece of wood and pound it home with a mallet. Remember the big long gouge along the top of the Cases in the last photo of Post #765?

I know that the upgrade kits for the two Rotary Transformers in 1945 included new sections of wiring harness. This new harness was all done in solid colour plastic sheathed wire, as opposed to the factory original white cotton and trace style of harness. Most of the Supply Unit would have to have been disassembled to do all that replacement work and from the wiring part, it was done very well. The looms that had to be disassembled were all very neatly relaced when finished. You can see a mix of all original, all new and blended throughout the Supply Unit. What I do not understand is why they replaced all the Shakeproof washers that had a great international reputation for being very reliable electronics hardware, with these big, external toothed washers that did not fit properly, when all the original hardware was right there in front of them in the first place?!? Crazy!

Time for some Egg Nog!


David

[David Dunlop]

Here is the photo from Jerry Proctors website. It is actually the right hand side of a Supply Unit owned by Denis Chouinard.

David

[David Dunlop]

Well, it looks as if Philco Canada was not only involved with the headgear manufacturing with RCA Canada for the 52-Set, but they also had the contract to build the Vibrator Unit Power Transformer T7A (CMC 97703), ZA/CAN 4413.

Another few discoveries when I flipped the Vibrator Unit over and at first thought the interior had been horribly rusted somehow, and then realized it was actually copper plated.

Then the odd stuff showed up again.

A very careful look confirmed virtually all of the components and wiring are factory original, but every original Shakeproof washer had been removed and most replaced with those ugly, oversized external toothed washers. Some screws were even found to have had Shakeproof washers under them at one time but they were removed and replaced with nothing at all.

When you look at all the hex nut hardware, you find it was originally given a coat of varnish at the factory, but several hex nuts and open screw ends now have an additional overcoat of a thick yellow ‘paint’ that is probably some form of Loctite.

The last two photos in this Post highlight yet again the very sloppy, indifferent workmanship performed by whoever worked on this Supply Unit. The pan head screw at the very lower, right rear corner never properly meshed with both pieces of metal to pull them in together. I have experienced this phenomenon myself many times over the years. The screw threads into the first piece of metal just fine, but with not enough pressure applied to the face of the first piece of metal as the screw tried to grab the second piece, the screw just spins against the second piece but continues to thread into the first, pushing the two pieces apart. Usually you can back the screw out and apply correct pressure and try again with success. Sometimes you might have to back other screws off a bit to allow for better alignment of the two pieces of metal for the last screw. The point is, it is easily fixable. Clearly, nobody bothered here, slopped some yellow goop on the end of the screw and walked away. Adding confirmation to the indifference, about halfway forward on the same side, a bulkhead plate is mounted across the width of the assembly using the same pan head screws. As noted in the last photo, the same problem occurred with the same indifferent response. What you cannot see here because it is out of camera range is the second, upper screw showing the same effects.

So a Supply Unit component that required no component upgrades at all, was torn apart to have perfectly good hardware replaced by the wrong hardware as part of an assigned task somebody clearly did not want to do. Could have been worse I suppose, but one more reason to track down a good supply of Shakeproof washers.


David

[James D Teel II]

That sounds like it might have been a school house unit; one that was taken apart and repeatedly put back together. My own army is known for things like that.

[David Dunlop]

It certainly has that look about it, James, though I don’t think 202 Workshop was a training facility, beyond the possible monitoring of recent Trade School Graduates til they came up to speed.

I think most Canadian Military Trade Training takes place at CFB Borden, north of Toronto. Anything new arriving into Military Service that needed maintenance/servicing, would likely see examples of the equipment going to Borden early in the acquisition process so the various schools could gear up appropriate training courses. However, there are others here on MLU better qualified than I am who might be able to confirm if Wireless Maintenance was taught at Borden and if so, if they maintained a supply of the various sets up there for training purposes.

David