Wireless Set No. 52 Canadian - Project

[David Dunlop]

This is quite an impressive wiring harness when you finally see it out of the 52-Set Receiver chassis. The perimeter rectangle for it in the photograph is 16 inches by 24 inches, and it would have been a very interesting workstation on the production line to watch in action.

I wonder how many of these harness looms would have been assembled in any given work shift?


David

[David Dunlop]

This is the only other free standing wiring harness in the 52-Set Receiver. In the photo, it sits within a 9-inch square.

It is found on the lower left front of the chassis, connecting the A.F. GAIN, NOISE LIMITER IN/OUT and HET. TONE Switches to their relevant circuits on the back and bottom of the chassis.


David

[David Dunlop]

This particular switch in the 52-Set Receiver wins the award for the longest switch shaft.

Its location on the underside of the chassis can be seen in the first photos of both Post #619 and Post #620 .The terminal wafer assembly on the switch is located at the back of the lower chassis, supported in place by a mounting plate that forms a part of the frame for the switch. The holes in the lower front of the chassis and lower front panel plate support the front end of the shaft. Total length of the shaft is 9-1/4 inches.

This is the SHARP FLAT Switch in the receiver circuits.


David

[David Dunlop]

This is the shorter relative of its 5.5-inch cousin I covered in Post #617 and is of identical construction. In fact, it is the description of this CONNECTIONS, Screened that confirms how both are put together such that the wire does not make contact internally with the tube.

An appropriate length of the tinned, solid copper wire is cut and a small bead of solder applied at the required distance in from one end and a ceramic end cap dropped in place down the wire. Ceramic fish beads are then added down the wire in sufficient number to fill the metal tube. This wire and bead string is then slid into one end of the tube and pulled into place. The ceramic end cap is added to the open end of the string and a small bead of solder added at that end to secure and complete the assembly. The ceramic fish beads inside the tube are small enough let the wire down the middle of them flex with the curve of the tube, yet stay centred in the tube.

In the second photo of POST #619, you can see this CONNECTIONS, Screened tucked in between the two long rectangular banks of coil/caps, at the right hand side of the gap.

David

[David Dunlop]

The next phase of this parts receiver disassembly is going to focus on the removal of the 3-Gang Tuning Capacitor and the Coils Assembly, RF, mounted directly above it. These two units take up most of the right front half of the receiver. I still have a few bits to think through before I forge ahead.

If you refer back once again to the 2nd Photo in Post #619, this is a view of the back of the receiver chassis, with the chassis resting on its left side. The upper centre section, with the nine evenly spaced access holes is the back of the COILS ASSEMBLY. The back end of the 3-Gang Tuning Capacitor, with its curved top and big splotch of red paint, sits directly to the left of the Coils Assembly. Three leads from the Coils Assembly still run to the V1A, B and C sockets to the right side of the photo. These leads need to be unsoldered from their valve socket terminals.

The photo attached today shows these two components from the front of the receiver chassis. From what I can see so far, there are five leads running from the lower Tuning Capacitor up into the Coils Assembly. All these appear to be solid wire leads and may prove a bit tricky to get at with a soldering iron. Then there is the need to track down where all the mounting hardware is and sort out its removal.

You will notice in the attached photo, the INDUCTANCES, RF (L10A) is mounted to the bottom section of the Coils Assembly and actually extends down, in front of the Tuning Capacitor. This is the large disc, roughly centered on the Coils Assembly. This means the Tuning Capacitor had to be installed on the chassis before the Coils Assembly went on. Interesting.

On the front of the finished receiver, L10A shows up as the FREQ. ADJ. Knob.


David

[David Dunlop]

My observations about the number of leads feeding up from the Tuning Capacitor below the COIL ASSEMBLIES proved correct. There were five of them: one coming out the left (inner) side of the Tuning Capacitor and four feeding up through the right hand side of the Tuning Capacitor cover, through small, metal sleeved holes. A bit of a challenge to get at with a soldering iron, but more on that later.

The mounting hardware for the Coil Assemblies is fairly comprehensive, involving 11 sets in total.

On the left side, there are three slot head, countersunk, machine screws. The two upper ones utilize hex nuts and external tooth lock washers on the inside of the receiver chassis wall to secure them. The 3rd screw simply fastens directly into the end of the front support rod assembly of the Coil Assembly. This rod is a three section affair and access to fit an external tooth lock washer on the interior of the left receiver chassis wall is none existent, so to prevent the support rod section at the end from unscrewing when the outer screw is removed, an external toothed lock washer was added to the left end of this outer rod section, between the rod end and the right partition wall of the Coil Assembly.

On the vertical, right rear lip of the Coil Assembly, three holes are provided which drop over three threaded studs fitted down the inner wall of the receiver chassis. With the Coil Assembles in place, three hex nuts and external tooth lock washers hold it in place.

The top, horizontal, left rear lip of the Coil Assemblies fits directly against the rear wall of the receiver chassis and a pair of round head SEMS Fasteners with external tooth lock washers goes there.

The vertical lip down the left rear side of the Coil Assemblies also has provision for three more round head SEMS fasteners and external tooth lock washers.

My approach was to remove all the hardware except the two SEMS fasteners on the top left rear lip first. Then it was easy to support the Coil Assemblies with one hand while removing the last two screws.

The Coil Assemblies is an interesting component when you get it out of the receiver chassis, for a closer inspection. In situ, and looking at it from the front of the receiver, it is clear it is built in three distinct, shielded columns. Each directly under the following Valves, from left to right: V1C Mixer, V1B Conversion Oscillator and V1A the RF Amplifier.

When you start looking at the Coil Assembly more closely, and pay a little more attention to the components identified on the back of it, you realize the three coils in each column, along with their supporting capacitors, are also laid out in a horizontal pattern of three distinct rows. The top row deals with Band 3, 7.0 to 16 MC’s. The middle row deals with Band 2, 3.5 to 8.0 MC’s and the lower row relates to Band 1, 1.7 to 4.0 MC’s.

Combining the Valves and their basic functions, along with the three columns of the Coils Assemblies, the arm waving functions of each column in relation to the Valve(s) it is linked to can be summarized as follows:

The left column is the RF Amplifier Coupling between V1A and V1C, working primarily with Valve V1C, the Mixer.

The middle column is the RF Oscillator working with Valve V1B, the Conversion Oscillator.

The right column is the Aerial Coupling working with V1A, the RF Amplifier. In the last photo posted today, you can see a long wire, with a red and yellow tracer, arcing towards the camera on the left side. This is the output lead that came from the Crystal Calibrator and travelled through the long shielding tube mounted directly above Valves V1C, B and A. The shadow of the tube is visible on the chassis back wall in the photo in the previous Post #635. This lead feeds directly into this right side column of the Coil Assemblies.

I am hoping nothing serious needs repairing on my main set receiver Coil Assemblies. It would be a very challenging component to work on, even by its own on the workbench.


David

[David Dunlop]

The other interesting discovery regarding the Coil Assemblies, RF, was that it was also considered a major sub- assembly of the Receiver by Canadian Marconi Company.

Along the top end of the left side mounting strip of the Coil Assembly another Production/ Control Number was found, as per the attached photo, this number shows as, ‘#6247’.

It is hard to see this number when looking at a fully occupied receiver chassis from the front because the mounting for the Band Switch gearbox blocks a direct view. Then factor in if one was not aware of the existence of this number, one would not be looking for it anyway.

So it seems that as far as the Wireless Set No, 52 Receiver is concerned, the receiver chassis, Crystal Calibrator chassis and the Coil Assemblies, RF chassis all had Control Numbers assigned to them during the production process.


David

[David Dunlop]

In the accompanying five photographs, this Capacitors assembly is shown with its ‘COVERS, Metal, Capacitor, No. C1 ZA/CAN 4226’ still fitted. The four wires feeding through the holes on the right side of the Capacitors are a very snug fit, and I thought I would defer to wrestling with them just once, when I need to resolder the wire going to the middle section of the capacitor.

In the front photo, you can see a four-digit number ‘4290’ stamped in black paint. Since these capacitors were of Canadian Marconi Company in house design and manufacture, this could also be another Production/ Control Number.

On the right hand side, an oddity in the design of the COVERS, Metal, shows up. The front most round head, slotted machine screw holding the COVERS in place, sits in an open slot in the COVERS. This would suggest an idea floated at CMC at one time to make the COVERS easy to remove, if needed. However, the remaining three machine screws all pass through simple holes in the cover. No slots there at all.

As noted with the markings stamped at the top of each slot on the right side of the Capacitors Assembly, the three capacitors in this assembly run in sequence from front to back as, C4A, C4B and C4C. The Circuit References for these are: Antenna, Oscillator and Detector.

In the rear view photograph, the CMC Part Number stamp runs across the middle of the assembly. Just above the ‘C.M.C.’ section of this number is a small Inspection Stamp, ‘INS’. A small blue paint dot in the lower left corner notes that this part has been tested as fully serviceable. I am not sure if the sealant used on the large adjustment screw is red paint or sealing wax. It is quite thick and fortunately shows no sign of being broken. The back end of the COVERS in this photo shows a blurred circular CMC Inspection Stamp and this one was redone on the Covers at the rear corner of the top, on the left side.

The fourth photo is the left side of the assembly, which is pretty straightforward.

The last photo shows the bottom of the Capacitors Assembly. The three countersunk screws, with red lacquer over them secure the Capacitors to its heavy gauge U-shaped, base plate. The three round head screws mount the Capacitors to the chassis floor of the receiver.


David

[David Dunlop]

What the Parts Receiver, SN 8349, looks like now.


David

[David Dunlop]

These large shields are the lowermost ones in the photo in Post #639. From left to right, they cover Coils L18A and L16A in the two Coil Assemblies, IF.

With the two sets of hex nuts and external toothed lock washers removed from the shield mounting posts on the backside of the receiver chassis, the shields lift straight back and away.


David

[David Dunlop]

This pair of shields cover the upper pair of coils (from left to right L19A and L17A) in the Coil Assemblies, IF, and differ from their lower counterparts only by the presence of small, metal sleeved holes in the end of them to allow the Grid Cap Clip leads from the coils inside to pass through.

Just enough of a difference to get an ‘A’ added to the end of their ID and a new ZA/CAN Number.

With regards to removing these shields, you have no choice; the Grid Cap Clips must be unsoldered from the ends of the leads. These leads are not long enough to allow the shields to slide up far enough on them to access their solder terminals inside the Coil Assemblies.

Once the Grid Cap Clips are removed and the mounting hardware removed behind the chassis wall, the shields lift off easily.


David

[David Dunlop]

Viewed from the front of the receiver, this is the left hand vertical pair of IF Coils, under Valve V1E, the 2nd IF Amplifier. The upper coil, L19A deals with the input to the 2nd IF Amplifier Valve V1E, and is supported by a pair of Variable Capacitors, C7G and C7H, acting as Trimmers. The Grid Cap Clip lead for V1E feeds out of the shield for L19A.

The lower coil, L18A, deals with the output from the 1st IF Amplifier Valve, V1D and is supported by a pair of Variable Capacitors, C7E and C7F, acting as Trimmers.

In the early production receivers, these trimmer capacitors were quickly identified as prone to failure in humid conditions and were replaced with much better ones and instructions were issued to upgrade the earlier capacitors when found in a set.

For the Grid Cap Clip lead in this Coil Assemblies, a lead wire would have to have been fitted, of sufficient length to exceed what was needed. The lead would have been fed through the shield and soldered in place, once the coil assembly was mounted in the receiver chassis, and a sleeve fitted over the soldered terminal. With the shield then mounted over the coil, the lead could then be trimmed to the required length, a black sleeve slipped over it and the Grid Cap Clip soldered in place. The sleeve was then tied in place. The sleeve on this Clip was a black woven one.

On the back of the chassis wall, six sets of slotted, round head SEMS screws and external toothed lock washers mount the entire coil assembly to the chassis. When the screws are removed, and the two shields up front, the entire assembly can be carefully pulled out of the back of the chassis. Use caution, however, as the black sleeves on the lower soldered terminals of the assembly make the fit quite snug. It does not hurt to compress these two sleeves inward slightly with one hand while extracting the assembly with the other hand, until the sleeves are clear of the rear receiver chassis wall.


David

[David Dunlop]

Virtually all the parts of this Coil Assemblies are identical to the one just discussed in Post #642, but because the electronic parts have different circuit reference numbers for maintenance purposes, this assembly gets a different Identification Name and CMC Part Number.

This assembly is located under Valve V1D when viewed from the front of the receiver chassis.

The upper Coil L17A, with the Grid Cap lead, deals with the input to the 1st IF Amplifier Valve V1D, and the lower Coil deals with the output of the Mixer Valve V1C.

Two Variable Capacitors, C7A and C7B act as trimmers for L16A, and two other Variable Capacitors, C7C and C7D act as trimmers for L17A.


David

[David Dunlop]

This Unit sits on the left side of the rear wall of the receiver chassis, directly under Valve V2A. The Circuit Reference is L20A, in the 2nd IF Amplifier circuit for Valve V1E. It acts as the coupling from V1E to V2A.


David

[David Dunlop]

This Unit, circuit reference L21A, sits under Valve V1F on the far left side of the rear chassis wall of the receiver. It is externally identical to L20A, except the coil within it has a larger OD than the coil in L20A.

Unit L21A forms part of the Het Oscillator circuit of Valve V1F.


David

[David Dunlop]

A bit of a collective title to cover off several related receiver parts all at once.

The 52-Set Receiver uses two British Valve types (Canadian Equivalents) for the main operating chassis, factoring out the self-contained Crystal Calibrator sub-assembly. There are eight ARP-3’s and a pair of 12Y4A’s. Both of the sockets for these valves are of a brown, phenolic board design, rather than Bakelite, or ceramic.

HOLDERS, Valve, 5-Pin, on 1-27/32 inch centre mounting holes, ZA/CAN 4734, are used for the 12Y4A’s.

HOLDERS, Valve, 7-Pin, on 1-7/8 inch centre mounting holes, No. C1 ZA/CAN 4305, are used with the ARP-3’s.

Both of these Holders mount from the bottom, or back of the chassis, using a pair of truss head, 1/8-inch diameter by 5/16-inch long, soft steel, tubular rivets. Commercially today, these two valve sockets/holders are known as ‘5-Pin’ and ‘B&’ sockets respectively.

At the same time as the above two Holders get installed on the receiver chassis, a third part is also fitted to the top side, or front, of the chassis to be secured by the same two rivets coming up from behind the Holders. This part is as follows:

BASES, Metal, Shields Valve ZA/CAN 4524.

In the three photos attached, the 5-Pin Holders are on the left and the 7-Pin on the right, with the Bases below them with the rivets.

Removing these Holders and Bases was relatively straightforward. I used a large enough drill bit in my cordless drill to cover the circular crimped rim of the tubular rivet in the base mounting holes. With the crimp shaved down about half or so, I then took a 4-inch Common Nail, centred it on the hollow end of the rivet and gave it a whack with a hammer. The point on the 4-inch nail was just long enough to push the rivet out the chassis metal with no damage to the Base.

There was an interesting discovery about these two Holders as the rivets came out.

Both Holders are made up of a sandwich of two phenolic plates. The Pin Terminals are crimped onto the lower plate. The top plate is then added and riveted in place by hollow brass rivets.

On the 5-Pin Holders you can see a pair of these small rivets at the 10 and 4 o’clock positions near the rim of the Holders. The Pin Terminals on these 5-Pin Holders are thin enough metal they lay quite flat against the top face of the lower phenolic plate when fitted in place. The top phenolic plate helps hold the Pin Terminals in place and also likely stiffens the overall Holder. When you look at the edge shot of the Holders you will see very little gapping between the two phenolic plates. Not so with the 7-Pin Holders.

The Pin Terminals for the 7-Pin Holders are quite robust by comparison to the ones on the 5-Pin Holder and they do not lay flat against the top of the lower phenolic plate at all. A large tubular brass rivet is used at the centre of the 7-Pin Holders to secure the top phenolic plate in place. This leaves a noticeable gap between the two plates, which if not resolved, would likely warp the Holders when riveted to the chassis causing long term problems.

To solve this problem, small phenolic washer-like spacers were inserted between the two phenolic plates to take up the gap where the mounting rivets were placed. During the manufacture of these Holders, these spacers were very likely lacquered in place to secure them, but after 80 years, the adhesive quality of the lacquer has failed completely. As I happily popped the first set of these holders off the receiver chassis, I was surprised to find several of these spacers on the workbench, along with a lot of fine yellow dust. Fortunately, all spacers were accounted for in the end.

The assembly station on the line where these Holders were fitted is another one I would like to have seen in action.


David

[David Dunlop]

Another generalized title to cover off the following three, related components in the Wireless Set No. 52 Receiver.

BODIES, Shields Valve, 1-5/8 inch dia. x 2-7/8 inches long, No. C1 ZA/CAN 4279

This item is made of nickel-plated tin, the upper end of which has been rolled back in on itself forming an inner open ring. Inside this ring, a felt washer has been cemented in place. This washer has a ¼-inch square cross section, a 1-inch ID and a 1-3/4 inch OD. This felt ring rests on the shoulder of the valve and when the Shield Body is fully seated in its BASE, the Valve will be fully seated in its Holder.

As per the example of this Shield Body in the first photo, the nickel plating can often wear off the tin externally. Not sure why, but the insides and the upper and lower ends of the outer surfaces that are covered by the Base and Cover, stay in pretty good shape. I have considered redoing the nickel-plating on these Shield Bodies but that would mean soaking the inner felt washers in a solution loaded with nickel ions that would stay in the felt once dried out and I am not sure that would be a good thing for the proper operation of any valve in the future.

COVERS, Metal, Shields Valve, 1-11/16 inch dia. x 1-3/4 inches long ZA/CAN 4233

These are the commonest Covers found in the 52-Set Receiver, with a single side slot for accommodation of a Grid Cap Clip lead if needed. They are made of a slightly heavier gauge of zinc-plated steel, for some reason. An example is in the second photo.

BODIES, Shields Valve, 1-5/8 inch dia. x 2-5/32-inches long, No. C1 ZA/CAN 4280.

This Shield Body was designed solely for use with the 12Y4G Valve used in the V2B, Noise Limiter in the receiver. This is a horizontally mounted valve found on the lower left corner of the rear chassis panel, directly behind the vertically mounted V1G Valve. Since clearance needed to be provided for the Wireless Operator to reach in and service/replace the V1G Valve, sufficient space was needed behind the V1G Valve to do so. Consequently, the standard Shield Body was shortened in length. This meant there was no easy means for the full shielding assembly of this horizontally positioned valve to be physically locked in place and there was the risk of the Shield Body vibration loose. Consequently, the solution Canadian Marconi came up with was to solder the Shield Body into its Base. In the third photo you can see the red lacquer markings from the factory on this solder work. The V2B Valve is an annoying valve to have to work on in this receiver. Tricky to remove from the shield and even harder to line up blind with the Holder to put it back in place.


David

[David Dunlop]

I have started to take a look at this little CONNECTORS Cable, and for the size of it, it is proving quite challenging.

For starters, there are two HT Electrical Wire specs lurking out there: 7mm and 5/16-inch. Convert those to decimal inch and you get 0.2755 and 0.312 inch respectively.

The Plug at one end of the CONNECTORS is supposed to have a bore of 0.295 inch diameter and the LUG at the other end an 11/32-inch bore which equates to 0.343 inch.

As you can see, one cable will be a sloppy fit and the other will not fit one of the terminal ends at all. Interesting.

So, does anyone possibly have one of these CONNECTORS sitting unneeded in a corner of the workshop somewhere, I can purchase?

Another small wrinkle appears to be that early production of this CONNECTORS used a shorter Plug than later production, but either will work between the Sender and the Coil, Aerial Tuning Assembly.

David

[Chris Suslowicz]

Er, I think you're mis-reading the description: there is no mention of the bore diameter in the plug (which is the standard 'F' rod simulator used on wire aerials and the 34-ft mast (etc.) Aerial Feeder No.9 that mates with the aerial base.

The description lists the outside diameter and length of the nickel-plated brass plug, and the length of the knurled portion. Nothing about the internal bore for the core of the connecting cable.

The wire aerials had the end simply inserted and soldered; Aerial feeder No.9 had the central hole tapped for a (2BA?) screw to take a tag and lock washer, and other cables had a plain central hole cross-drilled and tapped for a grub screw.

The lug on the other end would be soldered and then either crimped around the cable jacket, or sleeved/whipped with twine for a suitable fit.

Best regards,
Chris.

[David Dunlop]

Hello Chris.

I hope you are not back on call again this week.

Here are the specs on the 'new improved' PLUGS taken from the Issue 2, 1 July 1948 Parts List. Note the longer overall length and knurled length.

I suspect the earlier version of the PLUGS may have resulted in too many Operators adopting a 'Mains Plug' approach to removing the Connector from the Sender Socket, simply giving the wire a good yank and thereby shortening its life expectancy.

I will post a photo of the LUGS in a moment.

David

[David Dunlop]

Here are the details for the LUGS, Chris.

The Parts Manual also refers to these, and a few others, as 'Sherman Lugs'. I am not certain if that is a reference to a Brand Name, or type of lug, however.

If I end up having to replicate the CONNECTORS, Single, 16-inch, I would prefer to go with the 7mm HT wire that I have on hand at the moment. That should fit the PLUGS just nicely but would tend to be a rather sloppy fit when seated in the bore of these LUGS.

I have just noticed, though, in the illustration I posted yesterday of the CONNECTORS that the ID Sleeve is located right up against the back end of the lug. If that ID Sleeve were in fact to also be seated fully into the bore of the lug to keep it in that location, it just might take up any slack between the 7mm HT wire and the bore of the lug. In theory, there should be no physical load at all on the lug end of this Connector. The lug would simply be dropped over the terminal on the side of the Coils, Aerial Tuning case and the wing nut secured…job done and it just sits there. It would be the Plug End that would be subjected to a lot of pushing and pulling force.

Cheers for now,

David

[David Dunlop]

Well it took a while, but my spare parts receiver has now finally been carefully reduced to its basic chassis assembly. It has been an interesting and informative bit of work. I now have a far greater appreciation of the incredible amount of design and planning work that goes into producing a piece of equipment like this in the pre-computer era. I started out just thinking of the line workers actually assembling it, but it is so much more than that, involving a lot more people with a huge variety of other skills.

The process also gave me a much better understanding of the layout of all the components and their interactions with one another in the various circuits in the receiver. Useful things to learn in this project!

The basic foundation of this receiver chassis turns out to be just four pieces of 13-guage, steel, sheet metal.

The main piece of sheet steel runs from the ½-inch lip at the upper rear, across the top, down the back and forward across the bottom, where it then drops to form the lower front section of the chassis and ends with another ½-inch lip folded under the front lower edge. Half-inch tabs are also present on this piece, folded back along the sides where they meet up with the two side panels. These side tabs provide a means for the spot welding to take place joining the three main chassis pieces together. The overall size of this piece would be on the order of 25-1/8 inches long and 15-7/8 inches wide. Where any tabs are located at folds, they were designed that outside corners would be full open at 90 degrees and any inside folds were set up for a 45-degree mitre.

The two side panels are basic dimensional mirror images of each other, 11-1/4 inches wide and 14-7/16 inches long, with ½-inch tabs, front back and bottom only. They really differ only in the hole patterns punched in each.

When the cutting, punching and brake work was completed on these three pieces, they were inspected and a small circular CMC Inspection Stamp was punched into them, ready to move down the line. The first two photos attached highlight these features.

The fourth piece of sheet metal making up the receiver chassis is a strip approximately 1-1/8 inches wide, folded in half lengthwise down the middle forming two ½-inch tabs at 90 degrees. This piece is 13-3/4 inches long with straight cut ends, and forms the lower rear edge of the chassis. It is butt welded in place with all external seams filled and ground smooth.

The spot-welds on the tabs connecting the main and side chassis panels are approximately 1 inch apart wherever possible and ¼-inch in diameter. The second photo also shows how the lower chassis strip and the upper rear edge both have all their external seams filled and ground smooth.

Photo 3 shows the inside of the lower chassis strip with the unfinished butt welds. Note that the zinc plating covers these welds. By ensuring all these external seams are smooth, it makes sliding the receiver in and out of its relevant Carrier that much easier for the Operator.

A number of smaller sheet metal pieces are spot welded to the chassis prior to it being zinc plated, but I am not sure if these small pieces would have been added to the individual chassis panels before they were assembled into one unit, or after.

The first two are the Upper Mounting Brackets passing through slots on either upper front side. These are made of heavier, 11-guage sheet metal. They have an offset stamped into them such that when the rear portions of them are spot welded to the chassis sides, the outside faces of the front sections projecting through the slots, line up perfectly with the outside face of the chassis side panels. This ensures a good fit when the receiver chassis goes in and out of its Carrier. The last photo in this Post shows this offset on the Upper Left Side Mounting Bracket.

The fourth Photo here gives a rear view of what is going on around the Right Side Mounting Bracket. Two other 13-guage metal strips are also fitted here.

The long vertical strip is a stiffener to support the Upper Front Right Subpanel Assembly. This is the small panel that sits directly behind the removable Upper Front Panel of the receiver, which supports the BAND Switch, FREQ ADJ Switch and AERIAL Terminals visible outside the receiver, as well as the Gas Discharge Tube Clips mounted inside, behind the two Aerial Terminals.

The larger, horizontal strip of 13-guage steel mounts the AirLoc Fastener Receptacle. A blue, spring steel spring assembly is held inside this receptacle. Note that the entire thing is covered in zinc plating.

The rest of the chassis information will follow shortly.



David

[David Dunlop]

Continuing on with what I have found when disassembling my spare parts receiver, the 1st Photo in this Post shows a front view of the three machine screws used for mounting the right rear side of the Coil Assembly RF to the back of the Receiver Chassis. They are slotted, pan head machine screws, 7/16-inch long by 6-32 NC in design.

A rear view of these three screws is in the 2nd Photo. Once they were screwed in place, the heads were welded to the chassis and then ground down to avoid any contact with the leads from components mounted on the PANELS, Phenolic, 22-Tag ZA/CAN 4690 (Discussed in Post #616.) that gets installed directly behind these screws later in the assembly process. Note the welded heads have been zinc plated.

The three small Grid Cap Clip lead holes with the metal sleeves pressed in place, and the larger sleeve for the AGF, NOISE LIMIT and HET TONE Switches sub harness are also all zinc plated, so must have been fitted before the plating process as well, along with the 15 small hollow threaded spacers riveted on the chassis for mounting the Tag Panels. The crimps on all these rivets show no plain steel at all, just zinc plating.

The one remaining item that was riveted to the chassis is the 2-3/4 inch solid steel support for the lower inside corner of the 8-Pin Connector Mounting Plate. The third photo in this post shows this support in place, and the fourth photo shows the back end of this support rivet head. All of it again, zinc plated. The open end of this support is tapped 7/16 inch deep for one of the 8-Pin Mounting Plate Countersunk screws.

The last Photo here today shows the 13-Guage reinforcing strip spot-welded under the upper right rear lip of the main chassis plate for the upper two mounting screws of the 8-Pin Connector Plate. If you look closely in the 4th Photo, you can see that the metal from the main chassis panel has been cut back with a countersink just to the point of the reinforcing plate beneath it. I believe this was done to avoid the two mounting screws from grabbing both pieces of metal when threaded home and spreading the two pieces apart in the process. The kind of thing that can happen, when you try and screw two pieces of metal, or wood together sometimes.

Once all these pieces were assembled. The chassis would have been zinc plated and inspected. All three main chassis parts show circular, blue, C.M.C. Inspection stamps on them. The chassis then probably received its Production/Control Number, and then had the blue Component Location ID marked applied and spot varnished. The next logical step would be installing all the Valve Holder Assemblies, and then, perhaps the Main Wiring Harness.

As I noted in the previous Post, this disassembly has been very interesting, though time consuming to do. And I needed the diversion to clear my head a little. I now plan to get back to getting the Main Set Receiver back up and running properly.


David

[David Dunlop]

True to form in a project of this size, I was cleaning up the shop a bit this evening and ran across a ziplock bag containing a single Capacitor and Cleat Assembly I had not yet catalogued.

While looking the capacitor up in the Master Parts List, I ended up flipping past the page with the CAPS, Holders, Watch, No. C1 on it. Something I have done countless times before. This time, however, something in the shading of the illustration of this part, along the front face, caught my eye. It appeared to be a rendering of the ZA/CAN Number cast in raised letter in the Bakelite. That jogged my memory.

About two years ago, I ran across an ad on-line from a chap in England who was selling NOS Bakelite Pocket Watch Holders. If I recall correctly, they were originally packed 10 to a box and he had several boxes of them available for sale. Since both my 52-Set Receivers were missing their Pocket Watch Holders, I ordered a pair.

When they arrived, I had noticed they had the ZA/CAN Number cast into the front face of the Caps. Checking the two Pocket Watch Holders on my Mk II and Mk III 19-Sets, I found both Caps were smooth, No sign of a number of any kind on them at all. At the time I just assumed the ones I had just ordered were probably British made NOS and thought nothing more of it.

Now I find the cast ZA/CAN Number on those two Pocket Watch Holders is what shows up in the 52-Set Master Parts List. Late discovery, but nice none the less.


David

[David Dunlop]

Well it was an interesting weekend, lots of pluses for the most part, and fortunately, only one rather spectacular negative.

I was able to narrow down the possibilities for the poor performance of my Main Set Receiver to the 1st and 2nd IF Amp sections and Valve V1D in particular. The valve itself was in good working order, but one of the other components that should have been working well with it, was not.

So I took the receiver, along with my Remote Supply bits over to a friends on Sunday morning to take advantage of his far greater electronic expertise, and shop full of test equipment.

As I had suspected, the receiver was working very well both ahead of and behind the two IF Amp stages and we eventually worked our way towards the eight small trimmer capacitors set up in two banks of four in the pair of IF Coil Assemblies. This receiver, as in my Remote Receiver, has the upgraded Trimmer Capacitors that were issued 24 April 1959 for replacement of the originals.

These new capacitors were identified as:

CAPACITORS, Variable, air dielectric 7.5 to 99.0 uuf CT1B100 and came with a NATO Stock Number 5910-00-126-1583

I suspect they are a Hammarlund product and the ‘CT1B100’ might be their part number reference.

The original capacitors issued with the 52-Set were also very likely made by Hammarlund. They are described as:

CAPACITORS, Semi Fixed, 5 – 100 uuf, 10% ZA/CAN 4478

The first we attempted aligning, C7D, would not budge at all and we could see it had a coat of varnish on it, none of the other seven had showing. That should have been our first clue. Five of the remaining seven were almost spot on and needed little or no adjustment. The two others were off by quite a bit and things were sounding very promising as they were brought into alignment. That just left C7D, so we headed back to it.

With the second careful attempt at turning the inner adjusting shaft, it suddenly unfroze and started turning and things were sounding REALLY good! It was just coming up to its optimum alignment point when we heard a loud metallic ‘ping’ from inside the capacitor, the adjusting shaft parted company with the adjustment tool and bottomed out deep inside the outer support tube, and the small hex head collar that locks the shaft in position bounced onto the bench. Not good!

An inspection of the hex collar showed it was cracked right through one face and the crack had a lot of dirt in it, all the way through. Taking into consideration the air gaps between the fixed stator and adjustable rotator plates inside this capacitor are on the order of 1/64-inch wide, and the adjustable rotator shaft suddenly moved inward under its tension spring load a good 5/16-inch. I am pretty much assured this capacitor is now toast.

The two photos show the shaft settled deep inside the capacitor now and the crack through the hex collar.

I do have 8 of the original capacitors available from the Spare Parts Receiver and a quick look indicates they are probably all in good working order, but it would be nice to find an original upgrade version for the replacement project.

OF course Hammarlund went out of business in the late 1970’s, so another challenge ahead with the Main Set Receiver. Sigh!


David

[David Dunlop]

A little bit of an update on the C7D Trimmer Capacitor Saga.

I have been able to successfully retrieve the C7D Trimmer Cap from the spare IF Coil Assembly salvaged from my Spare Parts Receiver. Only two soldered connections to deal with, both involving a very tight wrap of 20 gauge solid copper lead, and I have never seen so much solder on connections like these two had accumulated. I used up nearly 3 inches of de-soldering wick on them before deciding there was no way I was going to be able to clean the terminals enough to unwrap the leads. So I had to finally resort to my least used and least favourite tool in the shop: cutters.

But the replacement C7D Trimmer Cap is now ready to install in the Main Set Receiver, along with its insulating shield for the long Rotator Plate Connector.


David

[David Dunlop]

The Project is in a temporary holding pattern for a while.

I realized once I had the spare C7D Trimmer Capacitor ready for installation, I did not have any 20 gauge tinned, solid copper hook-up wire available in black insulation to make up the two connections between the C7D and its related coil. I have now ordered a 25-foot spool from the local Electronics Shop and have to wait for it to come in for pickup.

In the meantime, I have continued to review the steps needed to do the swap of the Trimmer Capacitor in the Main Set Receiver. It has been an interesting process with several modifications taking place in my head over the last few weeks.

Step 1 is I have to unsolder the Grid Cap Clip for Valve V1D inside the front section of the receiver and solder on a temporary extension of about 6 inches. This lead only has 2-3/4 inches of free place with the Grid Cap Clip removed before the lead will disappear inside the coil shield. The shield cannot be removed because there is not enough clearance to do so with the front panel attached to the receiver. The extension will allow me to retrieve the Grid Cap lead and re-solder the clip to it when the swap of C7D is completed.

Step 2: On the back side of the receiver, as shown in the attached photo, The C7D Trimmer Cap is the top most component on the left hand diagonal IF Coil Assembly. From approximately the mid-point of the assembly to the top, there are three individual wires that will have to be unsoldered: a long one going up above the coil assembly and a medium and short length set at roughly the mid-point. With them free, the large wiring loom coming off the bottom of the coil assembly, leading to the SHARP/FLAT Switch is the only thing holding the coil assembly in place once its mounting screws are removed.

The two IF Coils are 3-3/4 inches long wrapped on brown phenolic tubes. Strips of cotton cloth tape hold them in place on the tubes and then the entire coils are dipped in bees wax to protect the very fine wiring of the coils.

The punched holes in the rear chassis panel have some pretty keen edges. It would not take much contact with them for the wax and wire coils to be trashed, so the entire assembly has to come straight back out of the holes roughly 4 inches to be safe.

The loom feeding to the SHARP/FLAT Switch has been sitting in that position for nearly 70 years and I have no way of telling for certain if it is natural or synthetic rubber. The wires have also been treated with fungicide varnish so overall are pretty stiff. There is only about 2-1/2 inches of play in that loom before it reaches its limit and the coil assembly will start to get pulled to that side. Not good.

My first thought was I would have to unsolder all the connections at the SHARP/FLAT Switch, which was not a popular thought in my head. I then remembered the disassembly process for the Spare Parts Receiver.

The only electrical connections at the back of this switch are to the two IF Coil Assemblies. The switch has a big long shaft that runs to the lower front of the receiver and the hole in the front of the chassis simply supports the shaft. The switch is actually held in place on the chassis by a mounting plate at the back end with two screws securing it. For reference, there is a photo of this switch in Post #633.

Step 3, therefore, will be to remove the knob from the front of the SHARP/FLAT Switch shaft and then remove its two mounting screws. The entire switch can then be moved back to clear the front panel of the receiver and then swung down and to the right in the attached photo to rest directly under the two IF Coil assemblies. It can then be careful moved straight back with the IF Coil assembly containing the C7D Trimmer Cap until the two coils clear the rear chassis panel. With lots of TLC…it should work…I hope.


David

[Bruce Parker (RIP)]

Originally Posted by David Dunlop

I have now ordered a 25-foot spool from the local Electronics Shop and have to wait for it to come in for pickup.

25 feet should cover this and many subsequent 52 set rebuilds. Are you not telling us something?????

Anyway great restoration and it's always a pleasure to see how you come up with modern solutions to 75 year old problems. I bet you are the only one of 7.9 billion people doing what you're doing.

And besides all of that, 52 sets are some perdy.....

[David Dunlop]

Gosh, Bruce.

As you probably know, the wartime era Military District 10 was headquartered here in Winnipeg at the old Ft. Osborne Barracks. The old ‘District’ structure was abandoned after the war and the ‘Command’ structure adopted and by the late 1950’s, Kapyong Barracks had been built just south of the Ft Osborne site, which was abandoned to the Provincial Government for use by a few Departments.

In the 1980’s the site, which had remained intact from its wartime days, was handed over to a private group and it became a new university campus.

I would LOVE to say I found 10 complete 52-Sets still crated in an old forgotten storage room, but no such luck! Not even one badly used one! But if it ever comes true, you will be one of the first to know!

This Project is definitely a challenge, but I really enjoy research and learning new things and that certainly helps balance out the challenges.

The other nice thing is the amazing assistance and support available from MLU members. As much as this site might be considered vehicle oriented, military vehicles all too frequently were equipped with complex, unrelated equipment like wireless kit, that draws expertise in from other areas. Sooner or later, all these little bits come together and we all grow that much wiser for it. Our sanity might be questioned a bit, but I think we do get wiser.

David

[David Dunlop]

Although I am physically inactive with the 52-Set Project at the moment, my Mind plays by a different set of rules. In this instance, it is firmly entrenched in the next step beyond getting the Main Set Receiver back up and working. It is merrily churning up all sorts of things relative to the Supply Unit.

One of the things on my Mind is the above noted parts, the conical rubber connectors between the various headsets and drop cords found on many wartime Commonwealth Wireless Sets. On the 52-Set, there are two 5-Point Sockets, No. 5 mounted amidships on the Supply Unit, of which one socket looks like it had a blow torch applied to the end of it, it is so badly deformed. So it will end up getting replaced with an NOS spare I have on hand.

Currently, on the “wireless-set-no19 Group” website in England, there is a very interesting topic running about the chronic failure of all sorts of electrical wiring in the Clansman and Larkspur wireless sets. The rubber insulations crumble rather like the wartime synthetic rubber tyres used to on CMP vehicles.

That thread brought me back to these wireless connectors. I have a headset connected to my Wireless Set No. 19 Mk III, which I still fire up from time to time and the plug and socket were last disconnected from one another some 20 years ago. It was a relatively easy thing to do. Gently flex the joint between the two pieces until the metal retaining ring popped out of its groove and then pull the two pieces apart. I tried doing that a couple of years back when I started the 52-Set Project and the first thing I noticed was the two rubber cones felt VERY hard and there was definitely no desire for the area around the joint to flex at all. So I stopped trying.

While looking for Headsets No. 10 for the 52-Set, I found a minty set on which the central rubber plug in the connector had been popped free. Why this was done I do not know, but it looked like a screwdriver had been dug about in the seam between the two parts to accomplish the task. Electrically this headset is perfect, but for the life of me I cannot reinsert the circular plug back into position. The rubber is just too hard.

What my Mind is playing with now is the notion I may very well get the complete 52-Set restored and running perfectly but not be able to connect a headset to it because all these conical rubber 5-Point Plugs and Sockets have hardened up too much over time.

So my questions are if anybody else has noticed these Plugs and Sockets have hardened up, is anyone still able to easily connect and disconnect these pieces on their wireless sets and is there a way to refurbish these pieces…just in case?



David