Wireless Set No. 52 Canadian - Project

[David Dunlop]

This arrived today from Amazon.

When I discovered I was dealing with an aluminum plate for the front panel of the Coil, Aerial Tuning No. 2 A, I realized I had not had any aluminum primer on hand since I worked on my WIRE-5 project back in the 1970's. Back then, the 'Go To' primer for aluminum was the green Zinc Chromate stuff used in the aviation industry and I was able to source cans of it from Perimeter Aviation here in town. I was not at all surprised to discover the price of this stuff has gone through the roof since the 70's.

When checking for alternate products on the web, this product came up and caught my eye because it is a white primer, not the old green I had used years ago. When I was restoring the various cast zinc knobs and handles on the rest of the 52-set a few years ago, I had to find a correct primer for working with zinc or galvanized items and the product I found was also white. So I will be using the same process for the front panel of the tuning coil. A first coat of the white aluminum primer. let is cure and give it a coat of standard grey primer and then the top coat.

Just a can of xylene to track down now and I will be good to go for spray painting down the road.


David

[David Dunlop]

The six Front Panel Mounting Brackets are another undocumented item in the Parts lists for the 52-Set. They are made from 1/8-inch thick by 1/2-inch wide, cadmium plated brass bar stock, cut into 1.5-inch lengths. These are them formed to create a 1-inch long bar with a 1/2-inch tab folded at 90 degrees at one end. Centred along the one inch base are two 11/64-inch holes, themselves centred 7/16-inches apart. The small tab is centre drilled and tapped to accept the cadmium plated RH slotted brass 8-32 x 3/8-inch panel mounting screw.

All six Front Panel Mounting Brackets are identical in their mounting to the wooden coil case with a pair of cadmium plated, 6-32 x 3/4-inch RH slotted brass machine screws, brass Shakeproof washers and brass hex nuts. If your Coil, Aerial Tuning No. 2 A has never been overhauled, or rebuilt, you will find once all the brackets had been installed, the hex nuts were secured with a dab of red lacquer. The one slight exception to the mounting process is found with the bracket in the lower front right corner of the coil case. This bracket has an additional brass fitting attached to it as part of the grounding arrangement for the aluminium plate front panel of the completed tuning coil. This fitting will get some separate coverage later, but since one end of it is also connected to the special front end machine screw for the right side Mounting Plate, these Front Panel Mounting Brackets need to be removed now to gain access to the Mounting Plate hardware later.



David

[Barry Churcher]

David, Xylene is available at Princess Auto for $14.99. I just got some there.
Barry

[David Dunlop]

At first glance, the two Input Terminals on the Coil, Aerial Tuning No. 2 A appear to be the most basic of parts. Then, when you get your first good closeup look, they suddenly turn into one of the most fascinating assemblies in the entire 52-Set.

These two Input Terminals are located on the lower rear corners of each side of the coil case, directly above the rearmost mounting screws for the two brass Mounting Plates located on the bottom of the coil case. As such, they need to be removed before the two Mounting Plates can come off the case.

On the inside of the coil case, you can see the brown phenolic resin plates securing the two Input Terminal assemblies to the sides of the case. These plates are 3/16-inch thick, 1-7/8 inches long and 3/4-inches wide. they are held in place by an upper and lower set of cadmium plated, RH slotted brass 8-32 x 3/4-inch machine screws, brass Shakeproof washers and brass hex nuts. As a first step, DO NOT attempt to undo this hardware and remove the plate assembly.

In designing the 52-Set, Canadian Marconi Company was concerned the Operators, under less than ideal conditions, could lose critical hardware, like wing nuts and lock knobs. They used two techniques to avoid such losses. One was to drill the tips of screws, mount the wing nut, or knob, and then fit a wire D-Ring through the hole to secure the hardware from loss. The other technique, as they employed here, was to fit the wing nut and then use a small punch and hammer to mushroom the tip of the screw slightly to prevent the wing nut from coming off. So neither the wing nut, or small mounting panel, will through the hole in the side of the coil case. However, if you first remove the hardware from the central terminal stud on the inside, things will become possible. From the outer end of the stud to the phenolic panel, there should be the folllowing plated brass hardware:

1) 10-32 hex nut
2) Shakeproof washer
3) 10-32 hex nut
4) Shakeproof washer
5) 10-32 flat washer.

With all this hardware removed, and with good lighting, you will notice a 1/4-inch ‘square nut’ in the middle of the panel. if you apply pressure with a thumb to the exposed stud in front of this ‘square nut’, while at the same time gently pulling and rocking the terminal on the outside of the case, this stud assembly will pop free of the phenolic panel. You can then undo the hardware securing the panel and remove it from the coil case.

Interestingly, this terminal stud is the only part of these Input Terminals toi get mention in the Parts Lists for the 52-Set. They are machined from 1/4-inch square brass bar stock and are identified as:

STUDS, Brass, Special, ANF 10-32, 1-21/32 inches long, No. C1. ZA/CAN 8048

The finished item was cadmium, or zinc plated, and there is enough information in the description in the Parts Lists that a decent machine shop should be able to replicate them today.

With the two Input Terminals safely removed from the coil case, the only components left to remove are the two Mounting Plates on the bottom of the case.


David

[David Dunlop]

Hello Barry.

Thanks so much for the tip. It is the exact same product as I found here at RONA for six dollars more. I shall be launching a Princess expedition shortly, but I must say, I do miss the ones when their yard was full of rows of half tracks, CMP's and WIRE-5 boxes, and mind boggling other bits.



David

[David Dunlop]

The last set of components to be removed from the coil case are the two brass Mounting Plates on either side of the case bottom, that support the four Airloc Studs which are used to attach the Coil, Aerial Tuning No. 2 A to either the top, or right side of the Carriers No. 4 for the 52-Set.

Each of these plated brass Mounting Plates are fastened to the coil box by three plated brass 10-32 RH slotted machine screws. On the left hand side, these three screws are all one inch in length, with matching plated brass Shakeproof washers and hex nuts. On the right side Mounting Plate, the same one inch long hardware sets are used for the back and centre positions. In the front position on this side, a plated brass 10-32 x 1-1/4 inch RH, slotted machine screw is used. The extra length is to allow for the fitting of the brass grounding strap connected to the aluminum front panel of the coil assembly. But the hardware for these plates does not end there.

Each of the six mounting holes is 3/16-inch diameter and passes through the 3/8-inch pine board bottom of the case, as well as the 1/2-inch square pine strip reinforcement found mounted in the corners of the case. From the inside, a 13/32-inch diameter countersunk hole has been drilled down into each hole 3/16-inch deep. In the bottom of each hole, in both tuning cases I have available, I have found a plated brass 10-32 flat washer with a 3/8-inch OD. These are needed to prevent crushing of the wood when the Mounting Plate hardware is installed. The countersunk holes appear to have been factory painted and I am not sure if these washers were originally fitted with dab of glue, or have simply stuck to the painted surfaces of the holes after 80 years of close contact, but not one of them was willing to fall out on its own. Each had to be carefully popped out with a thin awl.

Getting this hardware out to remove the two Mounting Plates is challenging. When the hex nuts were originally fitted, they end up just below the surface of the wood in the countersunk holes, so are inaccessible by means of a spanner or 1/4-drive socket set. This took a bit of thinking on my part to solve.

Ideally, to keep the hex nuts from rotating with a potentially sticky screw, the hex nut needs to be held in place directly. I was hoping my various parts bins might have held an old bicycle tyre inner tube from which I could punch out a nickel sized disc of rubber. No such luck. But I did find a scrap piece of canvas from which I cut a one inch square pad. I then wet it just to the point of being slightly damp.

With a little experimenting, I found that the 1/4-inch socket in my quarter drive set was the perfect size to fit freely inside the countersunk holes in the wood, while also fitting freely over the tip of the machine screw. By placing the damp bit of canvas over the hardware, I could then fit the quarter drive setup on top so the rim of the socket was resting fully on the face of the hex nut. I did this with the coil case resting on one side at the end on my bench just far enough the Mounting Plate assembly cleared the bench and the side of the coil case was flat on the surface of the bench. In this way, with pressure applied to the faces of the hex nuts, all the three sets of hardware on the left side Mounting Plate, and the back two sets on the right side, all came apart easily.

The front screw set on the right side Mounting Plate is the 1-1/4 inch machine screw that has the additional Shakeproof washer and hex nut set holding the brass grounding strap for the front panel in place. With this first hex nut/washer set removed by conventional means, the brass ground strap can be removed to expose the recessed second hex nut and lock washer. The 1/4-inch socket was deep enough that with the canvas snugged down on the part of the hex nut facing into the coil case, this set of hardware also came off easily.

The coil case now sits free of all its fittings, except for the green felt pad glued to the bottom.

My apologies that this post turned into such a ‘Natter’.


David

[David Dunlop]

This is another unrecorded 52-Set item in the Parts Lists, so I thought it should be documented here as much as possible, in case somebody ever needs to fabricate a replacement.

It is made from 0.035 inch thick brass sheet and has been plated with zinc, or cadmium, upon completion. The basic form is an L-Shape, punched from the brass sheet. The main body is 3/8-inch wide and 1-9/16 inches long. The foot of the “L” is also 3/8-inch wide and 13/16-inch long. At the inside junction of the “L”, a 1/16-inch wide notch has been punched 3/16-inch into the main body. This has been done to allow the outer 1/2-inch of the foot to be bent upright 90 degrees at a very sharp angle, without tearing or warping the brass sheet.

The hole in the base is 3/16-inch in diameter, centred 1/4-inch from the end. The hole in the foot tab is 5/32-inch in diameter, centred 3/16-inch from the end of the tab.

The first photo shows this grounding strap sitting as it does when fitted into the coil case. The second photo is the ground strap simply tipped over onto the foot tab.



David