Wireless Set No. 52 Canadian - Project

[David Dunlop]

Hello Chris.

I checked several references on hand for this particular wire and none provided any notes on the lay of the stranding.

Also, as brilliant a job as the wartime illustrators did with the Master Parts List, the thinness of the 14 gauge wire was beyond their ability to detail the look of the windings. Our scanner is currently sulking so I cannot add an image at the moment. The illustration does show, however, that the last foot of wire is wrapped around the coil a couple of times, pulled back up the coil about six inches and wrapped off around the coil once more. This forms a kind of handle the coil could be carried with and the opposite side of the coil fans out slightly, since it is not secured. I suspect that when the coil of wire was packed in the Remote Operating Case, the open end of the coil went in first to keep it all in place, with the 'handle' at the top for easy retrieval when needed. This modern coil I got used electricians tape to secure the coil and I have seen others using plastic twist ties.

It would be interesting to compare original British wartime 19-Set Horizontal Aerials to Canadian made ones. The tighter you wrap the stranding, the more copper wire gets consumed, so a finished 100 foot run of stranded wire will hold considerably more wire than that when done. Actually, the central core wire would be the only one to be 100 feet long. the other six wrapped around it would all be longer. If you needed to conserve copper during the war, loosening up the wrap in stranded wire would certainly help. One would have to be careful, however, as if the concentric wrap is loosened up too much, it will degrade quickly into a 'bunched' wrap, which can become a complete rats nest to work with in no time.


David

[Bruce MacMillan]

decades ago I worked for a Canadian electronic distributor (Cam Gard Supply based out of Winterpeg) and we sold miles of stranded aerial wire. Looking back through the catalogues I saved the only info was that your choice was 7/22 or 7/24 stranded. The twist didn't seem critical.

[Chris Suslowicz]

Originally Posted by David Dunlop

Hello Chris.

I checked several references on hand for this particular wire and none provided any notes on the lay of the stranding.

The annoying part of all this is that I found the actual specifications on the Defence Standards website, years ago, and asked a wire manufacturing company how much it would cost to manufacture some (it was, of course, prohibitively expensive for a short run - I didn't need it by the mile).

If I saved a copy it's on a computer with a dead power supply (that's buried somewhere in the "I may want to resurrect this at some point" pile).

Shortly after I jokingly commented that "We ought to take a copy of the old battery specifications to reduce our load on their server" (but thankfully not before I had copied everything we were likely to be interested in) the Defence Standards website first deleted all the obsolete specifications, and later made the site private, requiring authorisation to look at anything.

It would be interesting to compare original British wartime 19-Set Horizontal Aerials to Canadian made ones.

I can do this. I've got one of the Canadian multi-section wire aerials (it came in one of the leather "Bags, Aerial Gear" and has been rewound on an American RL-29 cable winder instead of the usual Commonwealth drum, and I have a selection of the British wire aerials issued with various sets (the WS19 set of six aerials and the later 100-ft No.5) on wooden board winders, plus a couple of wire dipoles for the WS53. There's also the aforementioned 41-yard packets of Wire, Electric, R4 and a 100m (I think) cardboard reel with a NATO Stock Number - and it all appears to be the same specification ever over a fie decade timespan.

The tighter you wrap the stranding, the more copper wire gets consumed, so a finished 100 foot run of stranded wire will hold considerably more wire than that when done. Actually, the central core wire would be the only one to be 100 feet long. the other six wrapped around it would all be longer. If you needed to conserve copper during the war, loosening up the wrap in stranded wire would certainly help. One would have to be careful, however, as if the concentric wrap is loosened up too much, it will degrade quickly into a 'bunched' wrap, which can become a complete rats nest to work with in no time.

David

"Rats nest" just about describes my store of kit. I really need to make some space, sort everything out, and catalogue it.

Best regards,
Chris.

[David Dunlop]

It has been an interesting year for this project, with just a few select items purchased for it, and a lot of thinking about the next steps. I started the year with two options for goals, one centred on the Supply Unit and the second on the Coil, Aerial Tuning No. 2 A. Both of these require working with solvent based enamel paints which required outdoor spraying in the garage or driveway. Both require application of the new replacement phosphor luminous waterslide decals, but in the final analysis, the Coil won out.

The Supply Unit requires extensive physical repairs and some electronic. The decals to replace number seven in total across the front panel and the big factor is little documentation for the work required to clean and repack the bearings in the two rotary transformers.

By comparison, the Coil assembly is in perfect working order, still needs the front panel repainted with the enamel paint, but has only two decals to deal with which makes a better option for getting that work right before tackling the Supply Unit. The wood is also in very good shape.

Another important factor is I have just enough Flat Army Olive paint left over from restoring the three Boxes/Cases for the 52-Set that the finished Coil assembly will match the other wooden items perfectly when done.

The only real fly in the ointment is that this Coil assembly was painted NATO Gloss Green both inside and out, which means a full strip down of all the metal fittings and a lot of sanding in a confined box. More outdoor work but the sunshine will help. I do have another Coil carcass, with only the exterior painted Gloss NATO Green, but the woodwork is shot with large chunks of wood missing, badly stripped screw holes and major cracks in the panels. Some key electronic pieces are missing or badly damaged inside as well.

So the chosen Coil assembly is now on the work bench ready for me to disassemble and log in all the parts so they all go back where they came from when finished. First photo is said item and the others are of the damaged second Coil.


David

[David Dunlop]

Stripping down the Coil, Aerial Tuning No. 2 A is a relatively straight forward process. If you just need to remove the complete chassis from the case for an inspection, or a minor cleaning, the four steps to do so are nicely explained on Page 139 of the Working Instructions manual for the 52-Set.

However, if a full tear down, including removal of the front panel from the chassis is needed, you will have to ensure you dial the Coil Tuning Counter back to its ‘0000’ Start Position and make sure it stays that way throughout your work. It is important to keep the coil and its counter in sync with each other, while disconnected from each other.

The first step after setting the Counter to ‘0000’ is to remove the 10, 3/4-inch, RH slotted steel wood screws securing the wooden back to the case. My approach has always been to identify everything and put it back where it came from during reassembly. Built into this process is the ability to find damaged items during disassembly and getting them fixed, or replaced, before everything goes back together. During reassembly, I also know the parts should fit just fine because they did when they came apart and I am not about to try and put a stripped item onto a perfectly good item and strip it in the process as well. May seem like an excessive process, but it has worked for me for decades.

You can see in the attached photos that the NATO Green has been applied in a very thick coat inside and out on this Coil Assembly. However, the possible bright side is that there are a lot of large chips in the NATO Green paint on the inside of the back cover, so the prep work during the repaint mat not have happened and this paint might come off fairly easily, when I get to that point.

With the wooden back out of the way, the next step will be to disconnect the three leads for the Aerial feeds in the bottom rear corners and the upper right rear, shown in the last photo.



David

[David Dunlop]

The second step in removing the Coil chassis from its case is to find the three leads, pointed out at the end of the last post. They are all 3/16-inch braided and tinned copper loom with ring terminals on the ends connected to the two wing nut terminals at the bottom, either side of the case, and the Lead In Terminal on the upper left side of the case (when viewed from the front). All of the electrical items on these three fittings are zinc, or cadmium, plated brass. A 3/8-inch spanner is probably the best tool for removing the hex nuts on these three fittings. The access to the Lead In Terminal is quite tight and the refitting of the hardware will be the most challenging with it.

I am not certain what sort of lock washer is supposed to be used on these three terminals. There was none on the Lead In Terminal, probably because of the limited access. The wing nut terminal below the Lead In had an external toothed lock washer that looked a bit too large to do the job. The wing nut terminal across from it had an internal toothed lock washer that seemed quite at home there. And, of course, none of this hardware has survived on my parts Coil assembly.

The first two photos show the before and after views of this hardware removal.

The last photo today shows the locations on the bottom of the Coil case where the three screws with flat washers are to be found. these come into play with the third step.

While we are here, however, take a look at the set of brass gears in the tuning mechanism on the centre left side of these photos. They have accumulated a coating of green copper salts since the sets 1966 overhaul, but the rest of the chassis and interior of the wooden case appears remarkably free of any other oxidation, or damp rot in the wood, and as I noted before, this Coil assembly performs perfectly electronically.


David

[David Dunlop]

Step 3 in the removal of the Coil chassis assembly from its case is to remove from the bottom, the three screws that have washers, pictured at the end of the last post.

It was a little disconcerting to see that whoever last fitted this hardware to the case had run these three screws down so hard, the flat washers had cut into the pine board so hard the outer faces of the washers were actually flush with the surface of the board and the wood was coned inward noticably around each of the three screws. Note the first two photos. the concern here was that the base of the coil assembly these three screws are securing to the bottom of the case, is not metal. Rather, it is a mere 1/4-inch plate of brown phenolic resin. There was a very real possibility the overtightened screws could have torqued the threads they cut in the resin so much that the threads would simply strip out of the holes when these screws were removed. Fortunately, all three screws came out smoothly and there was no sign of resin dust or particles stuck to the screws. These cones in the wood will have to be filled in and levelled, and the flat washers carefully re-flattened when reassembly takes place.

The three chassis mounting screws are 3/4-inch, RH, slotted self-tapping machine screws with a 1/8-inch diameter shank and a 20 thread pitch. I have run across 1/4-inch long versions of these screws in wireless equipment over the years which have a small V-shaped notch at the tip. These longer screws do not have that notch for some reason. The threads just run out about 1/16-inch from the tip.

The flat washers are 3/8-inch OD with a 1/8-inch diameter centred hole.

At this point, the coil chassis assembly is only secured by six screws around the perimeter of the front panel. These six screws thread into six small steel brackets fitted around the inner edge of the case, each bracket held in place by a pair of small machine screws and hex nuts. See the last photo of my Parts Coil to get an idea where the last removal step is headed.


David

[David Dunlop]

As noted, with the removal of the required six screws from the front panel of the Coil chassis assembly, it is now ready to be removed from its case. The first photo here shows these six screws removed. These screws are a zinc, or cadmium, plated 8-32 x 3/8-inch RH slotted machine screws.

The designers at Canadian Marconi Company seem to have thought of everything with the 52-Set. The coil chassis is quite heavy and rests on a large plate of 1/4-inch brown phenolic resin. This is an important insulator for the coil assembly and can be damaged, so the designers added a sheet of green felt to the bottom to the Coil Case for the chassis to rest on and this also makes it quite easy to slide the chassis in and out of the case.

To extract the chassis from the case, it must be slid forward to release the front panel from its recess. this requires a forward movement of 1/4-inch. The safest place to push the chassis forward is to place a finger on each bottom corner of the phenolic resin chassis plates where the side and bottom plates meet at the rear of the assembly. See the second photograph. Apply equal pressure to both sides and push slowly.

Remember that bottom central bracket I pointed out earlier that the front panel is secured to, in Post #1093? The one with the gap cut out in the resin plate around it? The gap behind the bracket and the bottom resin chassis plate happens to be 1/4-inch. When the resin bottom plate hits this bracket, the lower edge of the front panel will have just cleared the lower lip of the wooden case and will drop down just enough to allow the top edge of the front panel to tip away from the upper lip of the case. You can then put your fingers under the lower edge of the front panel and lift it all up enough for the bottom phenolic plate of the coil chassis to pass over the bracket and you can carefully slide the entire chassis assembly out of the case.

The third photograph shows the green, felt pad clearly in the now empty case and the last photograph shows the Coil chassis assembly now sitting on its own.

Time for a glass of wine.


David