Wireless Set No. 52 Canadian - Project

[Chris Suslowicz]

Originally Posted by David Dunlop

The standard GSTP Pocket Watch used by the Canadian and British Armies during the war had specifications that all the watch makers complied with to the best of their ability during the war. Just like other war production, however, what was available to wartime watch makers varied enough that the size standards in particular were often not met exactly. Adding to the problem, for security reasons, all G.S.T.P. pocket watches bore no maker names on the watch face, and to really mix things up, it was very common practice for the watch parts makers to be supplying more than one watch manufacturer. You cannot rely on the look of the face, hands, crystal or other bits to accurately identify what company made the completed watch. All that information is stamped in code on the chassis of the movement inside the back cover of the pocket watch. That coded information will tell you who made the movement, who made the watch, the model number of the watch, the serial number of the watch and often the month/year, or year, of manufacture.

Not strictly true: a lot of the British watches have a maker's name on the face, and a serial number on the back. (Of course, it's now difficult to trust watches being sold on eBay (etc.) because there's a big incentive for the unscrupulous (nay, crooked) seller to erase or add markings, or change the dial for one marked Rolex or Omega, in order to inflate the price.)

I have four, all British and all different makers. All have the standard Ball winder on the top of the stem, and a ring fitted to the stem for adding a watch chain or lanyard. All are stamped on the back of the case G.S.T.P. with a serial number and broad Arrow. Interestingly, only one fits like a glove in any of my pocket watch holders and it is also the only one fully working still. It is currently mounted on the front of the RCA Speaker Assembly on my AR88LF. Another watch is mounted on my 19-Set Mk III and fits nicely (ever so slightly loose). A third one is quite loose and is mounted on my 19-Set Mk II. If the set was in a moving vehicle, it would rattle around a bit in the holder.

GSTP = General Service Trade Pattern (or possibly "Temporary Pattern") and were standard (-ish) pocket watches for the period.

There was (briefly) a "Watch W/T Non-Magnetic" which was actually _cheaper_ than the GSTP watches, having a chrome-plated iron case to screen the movement from the magnetic fields of generators and rotary converters in the wireless sets. They were later found to be unnecessary (and also less accurate, being cheap).

The last Pocket Watch I have has an original leather lanyard and sits on my radio bench. If I try and insert it in any of my Pocket Watch Holders, the ring is positioned slightly lower on the stem than the other three watches so it prevents the watch from dropping low enough into the holder for the bottom part of the watch to be secured. The crystal would probably get broken on this watch if it was in a holder on a wireless set that was in a wireless vehicle going across country. Or the Bakelite holder would get shattered.

The GSTP was a standard issue pocket watch, and not intended for fitting to equipment or use in watch holders. The massive expansion of radio usage meant that the original nickel-plated brass watch holder (on the No.1 and 11 sets) couldn't be produced quickly enough and it was replaced by the Bakelite version we (mostly) see today. The watches for those are mostly the 'B' series, produced without bows (the ring for a lanyard or chain on the winder stem), and usually with a short stem (probably specified for the WS19 Mk.1 which caused trouble with some watches being unable to fit the WS19 Mk.III because the power supply connector was a larger diameter and too close to the watch holder as a result). Earlier sets had the watch holder at the top of the front panel with nothing above them, but the WS19 was designed to fit a restricted space in an AFV.

When a watch is mounted in a holder on a 19-Set, or the AR88 Series of receivers, the operator has full access to the winding ball on top of the stem, even with the guards in place on the 19-Sets. It gets very interesting, very quickly, however, if you install one of these round ball GSTP Pocket Watches in the holders on the 52-Set Receivers.

Try a 'B' series watch with no bow, it is more likely to fit. (Note: a lot of surplus watches will have been retrofitted (frequently rather badly) with bows for subsequent sale.)

When I first saw the illustration of the pocket watch Canadian Marconi was using with the 52-Set, I thought it odd the watch used the flat style of winder on top of the stem, and that there was no ring. None of this made sense to me until I tried fitting the standard GSTP Pocket Watch into the two holders on my 52-Set and could not get any of mine to fit properly or be accessible to wind and change time. It was then that I realized how smart the designers and engineers were at CMC. They anticipated the problem and solved it with a custom pocket watch for the 52-Set. The flat top winder is only half as high as the ball winder and without the ring, the operator can easily wind and change the time on either pocket watch when it is in place.

Yep!

Another feature utilized by CMC was to ensure the pocket watch they needed for the 52-Set was none magnetic. This additional step would ensure these watches would keep running accurately for wireless use in such close quarters to high RF voltages. There was no risk of the movement parts all becoming mini-magnets attracting and repelling each other to a complete halt.

Not RF, it's the magnetic field from the rotary transformers (Dynamotors, "Anode Converter", etc.) that they were worried about - and probably more about eddy currents induced in the balance wheel slowing it down, which would vary according to the amount of time the set was in use and so couldn't be easily "adjusted out" by the radio operator.

The "Signals Office" used a GSTP watch but didn't adjust the time very often - they kept a record of the "error" relative to the 21:00 time broadcast from HQ and (presumably) adjusted the watch when the difference became too great. (Saves wear and tear on the watch, and they'd just add/subtract corrections in the paperwork, as required.)

I have a few "B" watches, some GSTP ones, an Australian W/T watch in a brass case (that some idiot removed all the black paint from and _polished_), and a Watch W/T Non Magnetic (with Roman numerals on the dial). I've also got my father's watch (which I must get restored) that _was_ used with his WS19 (because the issue watch was unreliable), and that was a present from his uncle (who was a Major in the army and ended up in Katyn).

There's an overview of military watches here:https://royalsignals.org.uk/photos/watch.htm

Best regards,
Chris (G8KGS)
Junior Password Gnome

[David Dunlop]

Yikes, Chris!

First of all, thanks for taking the time to post all that information. The ‘humble’ GSTP pocket watch is a far more complex topic than I ever imagined.

When I was trying to find appropriate watches to mount on my wireless sets a few years ago, I did run across a number of such watches with names on their faces, but confusion set in quickly with many comments being found on this that these were maker names and other comments they were just the names of ‘bespoke’ military tailors where officers would go to get kitted out for custom uniforms. Out of that confusion I assumed makers were unlikely in wartime to advertise themselves, so all those names were more likely just tailors who did not think the officers would be dumb enough to get captured. Beyond that, most of my research information focused on a handful of North American watch makers, as the most likely candidates to have produced the Canadian Army pocket watches.

Interestingly, the steel cases came up in the NA readings I found regarding none magnetic watches with comments they were not that good. Three or four very odd alloys were discussed that had been developed in the years prior to WW2 for making the watch main springs and other movement parts that seemed to be quite effective. These alloys had very odd names that made me wonder if they had not been discovered while excavations were underway in the Mile Forts along Hadrians Wall.

Sorry to hear about the polished brass watch holder. I have also seen that done to wartime military compasses, sniper scopes and binoculars ‘to restore their true value’.


David

[Chris Suslowicz]

I think Waltham and Elgin were the major American suppliers of watches (certainly to the British under Lend -Lease), and they were just their standard watch. My suspicion is that the Canadian WS19 Supply Unit No.2 had the watch holder moved to the front of it (instead of being on the set) was to solve the problem of tall winding stems.

The Australian watch (not a watch holder) should be finished in black "opticians enamel", I think, but mine has been "got at" by the Mad Brass Polisher[TM].

There's worse: I've seen optical instruments polished and CHROME-PLATED at some events! (Theodolites, heliographs, Instruments Flash-Spotting, and so on - they would never have been accepted for service with that finish.)

On the subject of Westclox (Western Clock Co.) - they also made daylight signalling lamps as well as morse keys for the WS19.

Best regards,
Chris.

[David Dunlop]

Another step closer to starting work on the Supply Unit.

These two cartridges of grease were picked up today, destined for the four bearings in the two rotary transformers. This grease follows the lineage of the original wartime grease used up until the 1970’s and discontinued by Imperial Oil shortly afterwards.

The original Andoc-C was a Grade 4, high temperature grease for electric motors. Imperial/Mobil no longer makes a Grade 4 grease, but their Polyrex line is still intended for this equipment today. Polyrex EM 103 is a Grade 3 grease but very hard to find in cartridges at a reasonable price. This Polyrex EM is a Grade 2 version rated to be stable up to 499 degrees which should be more than adequate for running the 52-Set on short term transmissions at standard room temperatures for the rest of its life. The tricky bit will be flushing out all the old sodium based original grease from the bearings before repacking them with this newer lithium based product.

I do not anticipate using very much of this grease, but the cost of two cartridges locally for pickup was well below the single cartridge price of this stuff I could find anywhere on the web. Leftovers will be transferred to the one pound tin and labeled, as part of the supplies for the 52-set shown in the Parts List.



David

[David Dunlop]

I think I have mentioned it before, this project would have been better started 50 years ago when 52-Set equipment was much more readily found. But then what is a project without challenges.

One of the items issued with the Remote Receiver and stocked in its Operating Case was a 100 foot coil of antenna wire; Wire, Electrical, R4, Mk 1. Next to impossible to find today under that specific identification. A little over a year ago, however, I stopped searching for the official military named product and started searching the internet using the actual description of the cold draw, stranded copper wire, provided in the Master Parts List for the 52-Set.

Not only did I discover this product is still alive and well and in production, but 100 foot coils can still be purchased from a number of Amateur Radio suppliers in the United States, or directly from the primary manufacturer, Davis RF, also in the USA. Most pricing falls in the low to mid $20.00 USF range but pay attention to shipping costs. Some will hit four times the value of the goods, or more.

I picked up my order in Pembina, North Dakota today and was delighted to find the coil was wound to within one quarter inch in diameter of the size of the coil illustrated in the Master Parts List. The weight of this coil comes in at 1.375 pounds and it was nice to finally have one of the items stored in the left side compartment of the Operating Case, actually in place.



David

[Chris Suslowicz]

Originally Posted by David Dunlop

One of the items issued with the Remote Receiver and stocked in its Operating Case was a 100 foot coil of antenna wire; Wire, Electrical, R4, Mk 1. Next to impossible to find today under that specific identification. A little over a year ago, however, I stopped searching for the official military named product and started searching the internet using the actual description of the cold draw, stranded copper wire, provided in the Master Parts List for the 52-Set.

How detailed was the description? (Somewhere I have the UK Military Specification for Wire, Electrical, R4 (and the heavier R7 type), and it may still be a current item - though it will be for specialist uses and a controlled item due to its scrap value.)

Not only did I discover this product is still alive and well and in production, but 100 foot coils can still be purchased from a number of Amateur Radio suppliers in the United States, or directly from the primary manufacturer, Davis RF, also in the USA. Most pricing falls in the low to mid $20.00 USF range but pay attention to shipping costs. Some will hit four times the value of the goods, or more.

I picked up my order in Pembina, North Dakota today and was delighted to find the coil was wound to within one quarter inch in diameter of the size of the coil illustrated in the Master Parts List. The weight of this coil comes in at 1.375 pounds and it was nice to finally have one of the items stored in the left side compartment of the Operating Case, actually in place.

David

That seems to have a shorter lay (i.e. rather faster twist rate) than the UK version, which was issued in 41-yard packets (a quarter-wavelength at the lowest frequency likely to be used) for making up or extending/repairing issued aerials. I'll see what I can dig out, but I think it was "one inch lay", or 12 turns per foot. I may be able to turn up the stores code and NSN, but these will not be for the WS52 "100-ft coil".

The "ready made" aerials seem to have been constructed without much attention to detail: I've got at least one where the first section (of something intended to replace the "set of six" wire aerials) is ten feet too long - making it unusable for the intended role. (One of the other sections is ten feet short, so it's a cutting error during manufacture, but it won't match any settings provided on the standard tuning charts - this may be why it survived WW2.)

Best regards,
Chris.

[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

[David Dunlop]

Well the first discovery about this Coil assembly with it finally out on the bench for a closer look, was a very positive one.

What looked like a very odd oxidation on the brass gear set for the coil tuning turned out to be a very nice distribution of a medium weight grease which was in excellent condition. Probably applied back in the 1966 Workshop overhaul for the set. The grease shall stay. It has earned its place.


David

[David Dunlop]

The design of the Coil, Aerial Tuning No. 2 A is slowly revealing itself, in spite of not much being said about it in the documentation for the 52-Set. The only technical references it gets are that it is not to be used at all above 10 Mcs and the Sender is to be connected directly to the aerial in use, and, that it is fully interchangeable with the Coil, Aerial Tuning No. 2, issued with the Wireless Set No. 9 Mk I Cdn.

One thing that has now surprised me, because I have missed it for several years now, is that the front panel for the Coil is cut from 1/8-inch Aluminum plate whereas all the other components in the 52-Set have front panels cut from 1/16-inch sheet steel. I am glad I now found this out as I have no primer for working with aluminum when it comes time to repaint the Coil front panel. That product is now on my ‘To Be Purchased’ list.


David

[David Dunlop]

While inspecting the Coil I am using for the 52-Set, I found ‘3978’ stamped in blue ink on the bottom side of the phenolic resin base of the coil chassis itself. I then found the same number stamped on the outer surfaces of the resin left and right side panels. See the first three photos. I am thinking this might be a Production Control Number used by Canadian Marconi Company during the manufacture of these coils, in a similar manner to the hand written four digit numbers found on the inside chassis surfaces of the other set components. The only other stamped marking I have found so far is the part number for the coil itself, CMC 119-521, which was stamped along the left side edge of the coil drum as shown in the last photo.

Now I have to see what I can find on the parts coil assembly.


David

[David Dunlop]

My parts coil revealed the number ‘8798’ stamped on the same parts as the four digit number that was found on the Coil assembly for the 52-Set, as per the first three photos.

The main difference was the Part Number for the Coil itself was not along the left edge of the drum, but now located on the left side plate of the drum. See last photo.

So if these numbers are indeed Production Control Numbers, then this Coil assembly came down the line a lot later than the first one. Is the new location for the coil Part Number as production change for some reason, or just a fluke?



David

[David Dunlop]

For such a small, and electronically simple component of the 52-Set, this coil assembly holds an amazing number of mysteries for me and they just keep popping up!

In fairness to the Engineers and Designers at Canadian Marconi Company 80 years ago, a fair bit of these mysteries are probably directly related to my limited practical and theoretical electronic knowledge related to this calibre of wartime wireless equipment.

The first, and still current mystery, revolves around the existence of the small cylinders found mounted just below the tuning gear drive assemblies on the right side plate of the coil chassis as per the first photo. They are not physically connected to any circuit in the entire coil case, just the 1/4-inch resin side plate. My first thought was they contained a coil intended to balance out the presence of the large mass of metal present with the tuning gear drive next to it.

Last night, however, I discovered these cylinders are not hollow. The ends of the two I have available to study finally revealed they are a tight roll of resin impregnated fabric. It is still possible that a very fine weave of non-ferrous mesh, or foil, is wrapped up within the coils of fabric, and these cylinders are serving some form of electronic purpose.

A new ‘longshot’ idea is these cylinders are nothing more than a spacer, or guard, to protect the tuning gear drive from getting knocked out of alignment when the coil assembly is removed from its wooden case. I say ‘longshot’ because a 2-inch piece of 3/4-inch wooden dowel would have been a far cheaper and simpler solution for this type of problem.

Adding to this mystery is the complete lack of reference anywhere in the 52-Set documentation to these resin cylinders.



David

[Mike Kelly]

Originally Posted by David Dunlop

A new ‘longshot’ idea is these cylinders are nothing more than a spacer, or guard, to protect the tuning gear drive from getting knocked out of alignment when the coil assembly is removed from its wooden case. I say ‘longshot’ because a 2-inch piece of 3/4-inch wooden dowel would have been a far cheaper and simpler solution for this type of problem.


David

Yes I believe they are just spacers that provide some mechanical stability to the rotary inductor frame and also prevent damage to the inductor unit mount which looks like a phenolic sheet material.

[David Dunlop]

Hello Mike.

The frame work is actually 1/4-inch phenolic plates, assembled at the factory with zinc, or cadmium plated, brass brackets and hardware, another part of the design showing CMCs desire to avoid the presence of ferrous metal in the construction of these Coils, Aerial Tuning No. 2 A, at great length.

They seem to have not wanted any latent magnetism developing within these units at all costs, and I fear I am not yet wise enough to understand why. Insert “Sigh” here.


David

[David Dunlop]

I have pulled this photo up again because it shows really well the four sets of components that are fitted to the wooden case for the coil, once the coil assembly itself has been removed. In order to refinish the wooden case, all four of these sets need to be removed. These components are as follows:

1) Aerial Output Terminal - located on the upper left rear side panel. The tip of the socket assembly for it is just visible in the upper left corner of the photo.

2) Input Terminals - there are two of these fitted with wing nuts located one on each lower rear side panel. The inner brown phenolic mounting strips are clearly visible inside the back of the case.

3) Panel Mounting Brackets - three each across the upper and lower front of the case.

4) Case Mounting Plates - mounted to the bottom of the case, one each side.

It should be noted, that with the exception of the casual mention of the two above terminals in the Operators Manual, none of these IDs are official and none of these parts can be found in either Issue 1 or Issue 2 of the Parts Lists for the 52-Set. Some of the individual parts making up these items are listed, however, but not all. I guess I should also point out here that I recently ran across a few pages from an Issue 3 of the Parts lists, dated 2 January 1953. I have no idea at this point if this was a few random page updates, or another full revision.

I shall cover the removal and descriptions of these four components in the next four posts.



David

[David Dunlop]

The first component I decided to remove from the coil case once the coil assembly had been removed was the Aerial Terminal. Not because it is in the way of anything else to be removed, but for the simple reason it is the most fragile component, which sticks out too much. The two main pieces of it are also in the realm of Unobtanium should they be broken.

This item is not referenced at all in the Parts lists as a complete assembly at all, but three components of it are, as follows:

1) INSULATORS, Ceramic, Bushing, Female ZA/CAN 4596

2) INSULATORS, Ceramic, Bushing, Male ZA/CAN 4661

3) SOCKETS, Antenna, w/sleeve, No. C1 ZA/CAN 4593

The last component is cadmium plated, 1/2-inch brass hex rod, fitted on its outer end with the cadmium plated brass socket with sleeve. The inner facing end is fitted with a 10-32 x 2.75-inch cadmium plated brass rod.

A pair of .020 inch thick brown phenolic gaskets fit between the insulators and the wooden case, one each side. These were custom made for the application. I found both of these gaskets had become glued to the NATO Green paint since 1966 which was a little concerning. I found bt using a 4-inch steel putty knife at very shallow angle, the paint was thick enough I could slowly press into it to get the blade below the gasket and slowly lift it. As the gasket slowly came up, I gradually advanced the blade until the entire gasket popped free. This worked for both the inside and outside gaskets.

These three pieces are clamped to the left side of the wooden coil case with a 1/2-inch OD 10-32 plated brass flat washer, plated brass 10-32 Shakeproof washer (internal tooth lock washer) and a plated brass 10-32 hex nut. When the connection is made to the internal feed from the tuning coil assembly, a 7/16-inch OD 10-32 plated brass flat washer is slide down against the hex nut already in place, the feeder cable fitted and then a second 10-32 Shakeproof washer and hex nut added to secure the connection. I am missing the second Shakeproof washer but have a few extras in my parts supply for when reassembly takes place.


David

[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