Wireless Set No. 52 Canadian - Project

[David Dunlop]

Another week. Another adventure.

As I had mentioned earlier, I want to first focus on getting the Remote Receiver back up and running. There do not appear (so far) to be any electrical issues. Most work will be cosmetic and physical in nature. However, at some point I am going to have to chase electrons into it and see what they get up to. Towards that end, a huge piece of the project arrived last week…a ZE 11 Remote Supply Unit.

I had known about this item for a while, but was also aware it related to the Wireless Set No. 9 Mk. I Cdn. The ‘correct’ Remote Supply for the WS-52 is actually the ZE 12. Then I learned from Jacques Fortin, out Quebec way, that there are only a few minor component variations between the two supplies and in fact Marconi had shipped ZE 11’s with initial production of the WS-52, until production of the ZE 12 was ramped up. So I bought this ZE 11.

Externally, the supply shows the usual dirt and nicotine accumulations for its age, but overall the original wrinkle green paint and white silk screened markings are in excellent condition. The underside of the cover assembly is finished in a very fine textured silver/grey metallic paint. I am curious now if this finish was also applied to the interior of the main set carriers and the remote receiver case.

The OZ4 looks a bit scruffy and has not yet been tested. The Serial Number (3892) has been stamped on a small metal plate which was then riveted to the top of the Choke cover, over top of the white stencil that notes a location for a serial number. I am wondering if initially these supplies just had a painted on serial number and then later Marconi switched to a metal plate format to extend the life expectancy of the identification?

The outside top of the cover has the number ‘3820’ hand written in white on it in two separate locations. Possibly a cover from a doner supply.

The AC cord is original, measuring about 7.5 feet. It had electrical tape wrapped around it a couple of inches above the base. At first I though this might be hiding a splice, but a closer look indicates a rodent of indeterminate size appears to have used the cord as dental floss at some point. I will have to take a closer look at that later.

In any event, it seemed the right idea to get this supply checked out and working as the first part of getting the Remote Receiver back up and running. Same initial goal, just a slightly different start point.


David

[David Dunlop]

With a bit of free time to play with this morning, I decided to dive into the AC Cord repair on the ZE-11 Remote Supply.

I assumed there would be two main parts to this work: a physical part dealing with the placement of the cord, and, an electrical part dealing with the usual desoldering and soldering of the two cord connections wherever they happened to be.

The first step was to remove the base plate from the supply. Straight forward enough. 12 small round head, slotted screws with lock washers, three per side. 11 screws were found to have the split lock washer style, the last one an internal tooth lock washer. Easy enough to eventually upgrade the latter to the correct style. Nice surprise inside the base plate. A very minty, lacquered circuit diagram for the supply.

After admiring the diagram for a few moments, I had my first reality check. Things can get quite crowded inside this equipment! It took a moment or two to confirm where the ac cord entered under the chassis. I had hoped the anti-strain devise used on this cord would be a simple knot tied into it to limit movement of the cord back out from under the chassis. Nope! This little puppy was held firm with a small ¼ inch clamp. Roughly dead center in the photo, you can see the small hex nut securing the clamp. Just to the right of the C22A Capacitor next to the ‘22’. Once you spot the nut, the clamp curve is quite evident with the two sections of heavy ac cord looping out. One lead ran straight to a pin terminal on the AC Selector Socket. The second shorter lead went up to a terminal on the 115V/230V Selector Switch.

Fine so far.

Step 1: Lets free up the AC Cord so the 4 inch damaged section outside is now inside where it can be removed and enough new, solid cord used to reconnect everything. The crowded conditions are really starting to make an impression on me now. The hex nut and visible screw securing the clamp are tucked under the C22A Cap just enough that I know removing the nut with a ¼ inch socket should be OK, but getting the nut and supporting lock washer back in place from underneath the chassis will be the tricky bit. Best check how accessible the screw is from top side. Of course. No visible screw topside!

A few careful measurements later, I discovered the screw used to secure the AC Cord Clamp is actually one of the screw posts fitted to the Transformer Cover on top of the chassis. That pleased me in so far as having figured out the transformer, choke and their respective covers must have been added to the chassis at, or just before, the AC Cord was fitted. But that did not cheer me up too much when I realized just how much more wiggle room the assembly line worker at Marconi must have had, compared to myself, when working on this part of the assembly.

In any event, out came the appropriate sized ¼ inch socket and off came the hex nut. Some careful use of a set of needle nose pliers, and out came the nut and the lock washer, followed by the clamp.

David

[David Dunlop]

Note to self: Find the stainless steel surgical clamps you bought years ago from Princess Auto. I bought them when working on my 19-Sets because they are brilliant for fishing loose bits like nuts and washers out of cramped chassis areas.

So I now had the AC Cord free to feed back down into the chassis area. I checked the Parts Listing for the ZE-11 and the factory cord is 8 feet in length. I needed to move just over 5 inches inside to get rid of all signs of rodent flossing and end up with actually more cord to work with when resoldering the two connections.

I was able to get the cord laid out and the clamp back in position easily enough and the clamp ended up on the screw post with just enough screw exposed that the lock washer would stay put on it. But how to get the hex nut back down squarely on the screw to feed it onto the screw? No finger room at all. I knew I had done this sort of thing before in working on my 19-Sets. A cup of tea later and it all came back to me.

Two options I had used in the past depending on how much access I had for a socket to fit.

If there is not enough space for a socket to safely start the hex nut home, without risk of an angled approach cross threading the nut, I used to use a pencil, piece of dowel, or similar item. Take the flat end and attached a tiny square of double sided tape. Then press the hex nut squarely on the end. Line it up square with the screw and slowly start turning. You can tell right away if the nut is threading its way home and the nut will simply twist free of the tape when the time comes. You can then safely fit the socket to the nut to finish the tightening process.

Alternatively, if you have the space to use a socket head. Pack a bit of tissue paper or paper towel into the opening of the socket head you need to use. Follow that with a small ball of plasticine, plumbers putty or that grey window putty used to seal window seams in the Winter. Then press the hex nut onto the putty. It will stay put while you turn the socket around to install the hex nut. Any putty that sticks to the nut when you are done is easily wiped away, and you can just poke a nail into the back side of the socket to push the paper plug back out. The paper cleans the putty out of the socket and away you go.

Turns out all this was the really easy bit. As I was starting to unsolder the AC Cord from the AC Selector Switch terminal, my 40+ year old soldering iron died. As it’s final farewell, it revealed just how the connections were made to this terminal and it was not what I had hoped for at all.

This will continue once I have sorted out a brand new, variable temperature soldering station and a fresh supply of desoldering braid.

David

[David Dunlop]

While rummaging through some more wireless bits boxes on the weekend, I rediscovered an old project package I had abandoned umpteen odd years ago, Trying to put together the really good parts from several Key & Plug Assemblies No. 9 Canadian, to make a good one for one of my 19-Sets. I think I stumbled across a very good assembly at a local sale and work on the project halted.

As it turns out, one of these Key and Plug Assemblies is needed for the 52-Set, and since I cannot do any soldering until my new soldering station arrives, I decided to reactivate the work needed and put a Key & Plug Assembly together for the 52-Set.

The project was simple enough, involving the transfer of the plug and cord assembly (in good condition) from a scruffy unit somebody had cut the leg straps from, to a very good unit somebody had cut the plug and cord from.

There are only two things that are a bit tricky about the work needed to be done: the two terminals on the positive and negative cord leads are crimped to the leads AFTER the cord is fed through the grommeted opening in the key base plate at the factory and they are too wide to slip back through the grommet as is, and secondly, there is an anti-strain loop woven into the cotton cord loom that slips over a J-Post Bracket at the back of the key bar assembly, just inside the case, This cotton loom is now some 60+ years old and is often not up to liking a lot of pulling and tugging, without breaking.

Step one is to remove the two terminal screws for the positive and negative leads. Make note the negative (earth) lead is the front most one. It has green cord wrapped at the base of its ring terminal and a green tracer woven into its loom. The line directly behind it is the positive one, with a red cord wound at its terminal lug and a red tracer woven into its loom.

Once you have removed the two leads from their terminals, remove the terminal screw on the back of the J-Post. It is only there to secure the anti-strain loop that has been slipped over the post. You will have to feed about one more inch of the plug cord into the key assembly at this point to give yourself enough loose cord for slipping the anti-strain loop off the J-Post. Once it is free, you just have to deal with the two terminal ring lugs.

The best way to remove the two leads is to hold a ring terminal with a pair of pliers, on one side of the lug, about one third of the way across the ring, Then take another pair of pliers directly across from the first and GENTLY and SLOWLY bend the ring to form a gradual, near 90 degree bend. You just want the diameter of the ring to have reduced enough to slide out through the metal grommet. Do the same to both ring terminals and you should then be able to remove the plug cord from the key assembly. Best to do it strain loop first and then one electrical lead at a time.

Reverse the process into the good key assembly. Insert enough cord that you can easily slip the anti-strain loop over the new J-Post and then gently snug it back. To reflatten the two ring terminals, I use a pair of needle nose pliers that have a smooth inner face to the jaws down near the jaw pivot point. Or, I sneak a pair of Debbie’s jewellery pliers that have smooth faces to do the job.

A couple of other points on these Key & Plug Assemblies. I have seen them with and without the bakelite guard fitted to the key bar, under the bakelite knob. I am not sure if this is just a case of these guards sometimes ‘disappear’, or if it reflects a change in production, with early morse keys lacking the guard and it being added later. No big deal if you never plan to use the key, If you do plan to use the key for CW work on a restored wireless set, I highly recommend you find a guard and install it.

Ever noticed the funny looking bakelite finger guard surrounding the morse key socket on the Mk III 19-Set? It is usually not there on the Mk II Set, which normally has either nothing, or a simple flat rectangular bakelite plate around the socket.

When you are working CW on a wireless set, the Send and Receive functions are controlled by the key plug. Fully inserting the plug places the set into transmit mode, pulling the plug half out of the socket places the wireless into receive mode. In Receive mode, one half of the brass plug assembly sits exposed outside the front panel of the set. If the wireless operator is in a hurry to transmit and pushes the plug back in with his fat fingers in the way, he will find full transmit High Tension power arcing into himself very quickly. Hence the development and installation of the finger guards. And the guards are great, but not perfect. The one on the Morse Key Bar and the knob will only protect you for the first 8 Amps. After that you are on your own.

Wonder how many wireless operators had their key strapped to their thigh first thing in the morning and spilled their cup of tea on their lap? Be more than their Rice Krispies going ‘Snap, Crackle and Pop’.

Hope this wan't too long winded.



David

[Chris Suslowicz]

Ah, you're fitting the cable backwards!

Replacement cables would be supplied with the appropriate tags on both ends, the key end would be attached first, and the cable fed through the grommet, after which the jack plug would be fitted to the free end. Workshops (ant telephone exchanges) had a hand-cranked jig to assist in screwing the jack plug on to the (ready made) cable, after which the crimped-on terminals would be fixed to the plug connections and the plastic cover screwed home.

I'd like one of those jigs, as I have replacement switchboard cables (in Chinese Red only, so far) to restore my Switchboard UC and its severely moth-eaten cables with.

Original British keys used the No.10 plug, which provided adequate finger protection. The Canadian keys had a more exposed 'hot' end, and the set was fitted with a plastic guard to reduce the risk of a 'belt' from the buffer stage HT (250 volts or thereabouts). I can't remember what the American keys used.

'Ham' modifications using commonly available jack plugs are a recipe for disaster if used by the unwary: Post Office style jacks with exposed screws (and the tail end of the brass body) are a hazard, and I hate to think of what the modern "all metal" screened plug would do to the user!

Chris.

[David Dunlop]

Hi Chris.

I’d prefer ‘Reverse Engineered’ rather than ‘backwards’.

Thanks for the assembly background. I didn’t realize a special tool was used to fit the plug end assembly, but do recall that end looked odd in some way in which the plug was fitted over the cable. I was concerned the old loom might split or tear if I played with it too much, so decided to leave it alone and go the back door route.

Cheers,

David

[David Dunlop]

Not much work done on the project this past week beyond restocking soldering supplies and getting familiar with the new soldering station.

However, the attached item arrived in the Mail on Wednesday, compliments of Bruce Parker. It has tidied up quite well and the few missing bits should be easy enough to track down. It is now penciled into the project right after I finish getting the two receivers up and running.

The real gem about this Coil, Aerial Tuning unit is that inside, it is still the original, pristine factory No. 2 Brown paint. Not faded at all from exposure to light of any kind for 74 years. It will definitely be the item scanned in for matching when the time comes for painting.

I thought I would now also post another photo of the project overall to date. Had to transfer in another section of wireless bench from the workshop to accommodate everything, but I had planned for that some years back when designing the Wireless Table setup. Top shelf holds the Main Set Receiver and Coil, Aerial Tuning. The lower shelf the Remote Receiver and Case, Remote Supply Unit, Accessories and spare parts receiver. The starting point Aerial Bag and F-Rods is still on the wall. The tea towel on the Main Set Receiver is not original to the 52-Set. It's 'Cat Proofing', held down by a 2-inch binder full of 52-Set literature/reference manuals.

So, some progress is being made after all.

David