Wireless Set No. 52 Canadian - Project

[David Dunlop]

Nearly a month ago, I had noted the meter readings on the Main Set Receiver were running low at 10 Volts DC and 130 Volts HT.

Since then, I have been running the set several nights a week for 15 to 20 minutes. Basically until it has warmed up and stabilized. During this process, the meter reading for the HT has settled in at a steady 125 Volts.

While killing some time this evening, I was reading through a few sections of the Operators Manual while the set was idling and noticed the comment in the Maintenance Section about checking the Meter from time to time to ensure it was correctly reading Zero when the Receiver was shut off.

I could remember checking the Zero Setting of the Meter on the Remote Receiver when I went through it, but could find no reference in my notes to doing so for the Main Set Receiver. The only references I had were to the fact the meters in both receivers were from two different makers. So I switched the set off. Sure enough! The meter needle pinned itself well below the Zero Mark. A quick adjustment of the Zero Set Screw at the bottom of the meter brought the needle spot on the the Zero Mark centre and I fired the set back up. I am now getting a steady 11 Volts LT and 135 Volts HT. A closer look at the resisters in the Meter Circuits will still be needed as that is the next likely point of issue. Some or all of these resisters may have finally gone off normal specifications.

David

[David Dunlop]

Back in Post #570, I had noted the LEADS, Aerial, 25-3/4 inch was temporarily installed on the 52-Set. This was basically to get the Leads in its final, correct position while the paint, lettering and clear coat were still relatively soft and uncured. I wanted that large lazy curve on the Receiver end of the Leads to get established so the Leads will be comfortable in that position down the road. Hopefully it will take on the nice aged look of the one Bruce has in his possession.

Since this was a temporary install (I still have the Receiver work to finish and have not started work on the Supply Unit) I had not bothered connecting the Sender end of the Leads to its terminal. I got to that point yesterday to find the pin terminal on that end of the Leads would not seat properly in the Sender AE Terminal Post. A closer look showed that when I was doing the final tightening of the AE Terminal when aligning the pin slot in it with the stem of the last Eye Screw, the AE Terminal must have shifted about 5 degrees clockwise. Just enough to jamb the pin from sliding all the way into the slot.

So out of the Carriers No. 4 the Sender came once again yesterday afternoon so I could realign the AE Terminal once more.

Getting the Sender in and out of the Carriers No. 4 is an interesting exercise. With the four mounting bolts out of the way, the two Handles at the lower centre of the Sender are definitely down where most of the mass of the Sender is located, but most of the resistance is in the upper left corner of the Carriers No. 4, where the two, 8-pin Connectors are located.

The Sender will slide out it seems, just until the four angle brackets are free of the Carrier. Then, the pulling force seems to have an upward element to it rather than straight out the front of the Carriers. This loads the contacting surfaces of the two 8-Pin Connector assemblies and they start to bind. Not a great thing for 75+ year old Bakelite. So to counteract that load, I now open the Blower Door so I can grip under the upper Sender Chassis lip with the fingers of my left hand and my thumb on the upper face of the Carrier, gripping that part of the Sender towards me while trying to put straight out as much as possible with the right hand Handle down low, with my Right Hand. The Sender pops out quite easily doing that.

To go back in, I find the Sender will slide relatively smoothly up until the two 8-Pin Connectors make contact with each other when significant resistance is met. At that point, I switch from pushing with the two Handles to placing Left Thumb centre top of the Blower Door and fingers down the left side of the front panel, above and below the Mounting Bracket. Right thumb on the right side Mounting Bracket. Applying pressure at those two points gets the two 8-Pin Connectors sliding into each other smoothly and alternating between those positions and the two lower Handles gets the Sender snugged home safely.

CMC did not expect the 52-Set Operators to have to pull the individual components out of the Carriers No. 4 at all. Unlike the classic 19-Set, all Operator valve servicing could be done via various removable panels, or the Sender Blower Door. As a result, there is no real information supplied in the Operator’s Manual regarding technique fro removal and installation. I thought this might help somebody sort it out sooner or later.

With the AE Terminal on the Sender now correctly readjusted, the Leads slides into place just nicely.


David

[David Dunlop]

A little bit of a spinoff from my last Post.

While temporarily having the Leads, Aerial 25-3/4 inch installed, I am not yet able to feed it through the Eye Screw located at the top of the front panel of the Supply Unit, because this particular Eye Screw has had the eye loop crushed in on itself.

If you look at the upper panel edge in this photo, you can see a set of four angled gouges in it, running from the right side to directly over the Eye Screw located at the upper right corner of the Sender Heaters decal.

When Jacques and I got our first close looks at the Supply Unit, we thought somebody had used a heavy screw driver in the upper panel edge to try and force the Supply Unit out of the Carriers No. 4 at some point in time. A close look at the inner face of the Carrier No. 4 in those four locations shows absolutely no damage at all.

So my current theory is that at some point in time, the Supply Unit had been removed from the Carriers No. 4 and was sitting on its own somewhere when a pair of Idle Hands came along with nothing better to do and decided to give the top edge of the panel several whacks with a ball peen hammer, or chunk of heavy bar iron. The one blow directly above the Eye Screw caught it and bent the eye closed.

Now noted for future repair.

David

[Chris Suslowicz]

Originally Posted by David Dunlop

A little bit of a spinoff from my last Post.

While temporarily having the Leads, Aerial 25-3/4 inch installed, I am not yet able to feed it through the Eye Screw located at the top of the front panel of the Supply Unit, because this particular Eye Screw has had the eye loop crushed in on itself.

If you look at the upper panel edge in this photo, you can see a set of four angled gouges in it, running from the right side to directly over the Eye Screw located at the upper right corner of the Sender Heaters decal.

When Jacques and I got our first close looks at the Supply Unit, we thought somebody had used a heavy screw driver in the upper panel edge to try and force the Supply Unit out of the Carriers No. 4 at some point in time. A close look at the inner face of the Carrier No. 4 in those four locations shows absolutely no damage at all.

So my current theory is that at some point in time, the Supply Unit had been removed from the Carriers No. 4 and was sitting on its own somewhere when a pair of Idle Hands came along with nothing better to do and decided to give the top edge of the panel several whacks with a ball peen hammer, or chunk of heavy bar iron. The one blow directly above the Eye Screw caught it and bent the eye closed.

Now noted for future repair.

David

It may have been in a different carrier when Mr Hamfisted attempted to pry it out (or force it back in, not realising that if you remove all the units from the carrier you have to remove the interconnection bar because the connectors definitely won't line up and fit it after everything is back in position). There may be another rack out there with matching damage,

Chris.

[David Dunlop]

Hi Chris.

That is another good possibility, actually, though the most likely place for Carriers to have been switched up between a number of 52-Sets would have been at No. 202 Workshop where all the major overhauls took place. That would suggest Mr Hamfist would have been in the military, perhaps a wireless operator, and that couldn’t possibly happen, could it?

Said Workshop may not have had a high priority for returning exactly the same equipment to a unit that submitted it for overhaul, as far as I know. As long as a duff set came in and a fully working one was returned, that might have been acceptable. Again, I do not know what the actual service procedures would have been.

I do know issues did occur where upper panels on Receivers were replaced on incorrect lower chassis assemblies, which caused a level of concern at 202 Workshop. That meant the Modification Records stored in their holder on the lower chassis no longer matched the serial number on the Data Plate mounted on the removable upper panel. Several Receivers are known to have survived with a mod moving the Data Plate to the lower chassis, where the left side Handle was originally located, and that Handle being moved over near the Meter. The work on all those receivers is identical, suggesting some form of standard was being followed.

The damage on this Supply Unit panel and Eye Screw definitely appears repairable at the moment, so in that regard, things are still on track. And besides, what fun is a project if there are no mysteries involved!

David

[David Dunlop]

An interesting day working on the Main Set Receiver yesterday. Some mysteries solved. Some new ones added to the pot.

The first thing that came to light, literally, was the discovery of a cracked outer terminal wafer on the Wave Change (Band) Switch, S6A, located on the upper right side of the receiver chassis. I had never seen this before, and initially thought I had been the cause as this switch sits right where ones hand instinctively goes to grasp the upper side of the chassis assembly when picking it up. The only reason I noticed it was because the work lamp on that side of my bench was on when I put the receiver down and the light created a shadow on the wafer that caught my eye. A close inspection, however, revealed the inner core of the fracture was not fresh, but had discoloured over a period of time.

In the attached photo, the crack runs through the empty 5th terminal position, between the two occupied terminals at the 5:00 position on the wafer.

Studying the wafer, I then noticed the none factory soldering point on the top right most terminal, where a new, plastic covered lead was soldered into the bottom side of the terminal, rather than onto the actual terminal itself that faces inward on the other side. This new lead runs up to the S5A Relay up behind the 8-Pin Connector on the back of the receiver. My thinking is that a repair was done at some point where the two retaining screws for the wafer were removed in order to pull the wafer forward to access the necessary terminal to effect the repair, There are several heavy gauge, solid copper wires soldered to this wafer and they likely resisted moving forward at the expense of cracking the wafer. The rotating contact plate and terminals on this outer wafer are still interacting correctly, so the old lead was likely cut away, the wafer carefully reinstalled and the new lead soldered to the bottom of its terminal.

That was the most exciting part of the days work, but I now know to take extra care when I dismantle this S6A switch from my Spare Parts Receiver down the road.

David

[David Dunlop]

The game plan with the Main Set Receiver yesterday was to first look at the LT and HT Meter Readings with the receiver running off the ZE-11 Remote Supply. The last time I had done this, the meter had not been properly set to its zero mark.

Before connecting up the ZE-11, however, I took the time to check the values of all the relevant metering resisters on the receiver. They all spec’d out in the same range of values as the ones in the Remote Receiver that works perfectly, the ones in the Spare Parts Receiver and the supply of NOS ones I have on hand, some of which I had to use to replace ones in the Remote Receiver that had gone ‘full open’. So all that looked good.

Since the ZE-11 would be operating in AC Mode, I set the meter on HT and hooked up the ZE-11. In AC Mode, the Remote Supply 12 Volt output is in AC Current and cannot be detected by the LT meter circuits.

When I turned the ZE-11 on, the HT reading went up just above 180 Volts for a fraction of a second and then dropped steadily to just a whisker above the 150 Volts mark, just as the white noise audio output arrived on the loudspeaker. Under no load, the output of the Remote Supply is about 30 volts or more above required specifications for the receiver. To test the output properly in these conditions, it is necessary to connect an appropriately sized resister across the 150 Volt output terminals of the ZE-11 as a load and take the reading from there. The meter was spot on with its information. With a fully discharged electrical system in the receiver, there is no load on the Remote Supply for a few milliseconds until capacitors etc. start charging up. As the circuits charge up, the load increases and the recorded voltage drops to its normal operating point. This told me the meter was in good working order. One big step forward.

While the Main Set Receiver was out of the Carriers No. 4, and to give the receiver a chance to warm up and stabilize, I let it run and turned my attention to the Supply Unit in the Carriers No. 4. I powered up my CPP-2 and hooked up a lead to the +12 Volt terminal in the Carriers No. 4 for the receiver. Then I realized I needed a second lead to ground on the Carriers No. 4 to complete the circuit. More on that later. I reinstalled a bolt into one of the receiver mounting holes and connected the second lead to it, and hooked up my multimeter.

When I turned the switch on at the Supply Unit, I got a perfectly steady 12.3 Volts DC reading that matched the output of the CPP-2 perfectly. I then shut the Supply Unit off and switched my leads to the +150 Volt receiver terminal in the Carriers No. 4. Since the vibrator supply portion of the Supply Unit, which feds the receiver, is a very similar design to the ZE-11 Remote Supply, I expected to get a high reading here. Something in the +180 Volt range, since there would be no load on the output for it to work with. Sure enough, when the Supply Unit was turned back on, the multimeter swung back and forth a few volts either side of the 180 Volt value. This was all good information.

I know knew the Main Set Receiver was reading correct voltages and behaved in a similar manner, to a point, as the Remote Receiver when running on the ZE-11 Remote Supply. But there were LT and HT voltage drop offs when the receiver was operating in the Carriers No. 4. I returned to the idling receiver and switched on the Calibrator. The meter was now reading about two whiskers north of the 150 Volt mark and it dipped just to the 150 Volt mark but as the Calibrator warmed up, the needle returned to its original slightly high position. Equally good news.

I went back to the Carriers No; 4, and reset the multimeter to the +12 Volt terminal for the receiver and switched the Supply Unit back on. 12.3 Volts steady. I then flipped the switch on the Supply Unit for the Sender Heaters. The 12 Volt reading dropped right to 10 Volts and sat there. I powered everything off and switched over to the +150 Volt terminal again. Turned the Supply Unit back on and got the reading bouncing around the 180 Volt mark once more. Then I turned the Sender Heaters back on and this reading suddenly dove down to the 110 to 130 Volt range and bounced around there. This leads me to suspect the Supply Unit will need a close look when its time comes.


David

[David Dunlop]

With the checks on the Supply Unit in the Carriers No. 4 out of the way, I returned to the Main Set Receiver, which was still idling away, on the workbench. Several interesting things have been going on with it.

First, upon warm up, the only audio output I have had is white noise static. I typically have the receiver set on Band 2, tuned to 5.0 KC. This is a convenient frequency because it means Bands 1 and 3 are already set at 2.5 KC and 10 KC respectively and there are nearly always good SW reference signals to be found at, or very near those frequencies one can tune the receiver to quickly. It also makes checking the Crystal Calibrator on each of the three Bands relatively quick as well.

Up until now, this receiver does not detect any signals from anywhere. Just constant static. The odd thing is that usually, on these receivers, if you touch the aerial terminal when the set is on, you introduce a bias to the incoming signal that changes the audio output somewhat. If you are wearing shoes, your body acts like a giant aerial and shifts the signal somewhat. If you are in bare feet on a concrete floor, your body becomes a ground for the signal and the output changes a bit as well. On this receiver, none of that happens at all.

My approach is to start at the very back end of the circuits, right up behind the aerial tuning at Valve V1A, the RF Amplifier and progressively work my way to the front end of the receiver. The first three stages are all ARP-3 valves and all run sequentially from right to left in the upper right corner of the chassis. These are V1A the RF Amplifier, V1B, the Conversion Oscillator and V1C, the Mixer.

First thing I wanted to do with these three valves was pull the shield caps and then touch the end caps of each valve to see if that might impart a bias to the audio output. No changes at all for all three. Next step was to pull the three valves and test them again. I have two NOS ARP-3 valves that both test in the upper 80’s on my valve tester. All three of these valves checked out in the upper 70’s, very close to one another. Good news, but it didn’t shed too much light on the issues at hand. Then for some odd reason, with the set nicely warmed up, I decided to check for Crystal Calibrator signals once more.

Nothing detected at 5.0 KC on Band 2 with the calibrator set at 1000. So I switched to Band 1 and backed the dial up from 2.5 KC to 2.0. And there was the calibrator tone, clear as a bell. I switched the calibrator to 100 and once again, there was the tone, just slightly less loud. When I switched the calibrator to 10, I had to really listen to the loudspeaker, but could make out the tone in the background. That made my evening!

A quick check on Band 1 at 2.0, 3.0 and 4.0 found the calibrator signals with similar intensities. So I switched back to Band 2 at 5.0 KC. No calibrator. I backed up to 4.0 KC and there it was again. But at 5.0, 6.0 7.0 and 8.0 nothing detected at all. One last look at Band 3 was now required. Nothing detected anywhere at all on that band. Overall good news, but I now need to do some thinking about why the Crystal Calibrator signal drops off the dial above 4.0 KC.

David

[David Dunlop]

My apologies for taking a while to post more information on this project. I am at the point where I have a Remote Receiver that is functioning very well, but not completely checked for electrical basics, and I have no idea when it was last aligned and calibrated.

By comparison, the Main Set Receiver cannot detect a signal to save its soul and even its own Crystal Calibration Signals drop off the tuning dial above 4.40 MC. and, when it was last aligned and calibrated is also unknown.

So to start, I took the Main Set Receiver and went through all the valves to test them and did a complete Meter Reading of all its valves internally to see what that told me, compared to the manufacturers specs in the Operators Manual. Since the same Grid Circuit is used to obtain the meter readings from each valve, I also had to identify and find the Bias Resistors used in each of these valve circuits to obtain the meter readings, to check the resistors for the ability to still be providing valid readings.

The meter readings were the easy part. Warm the receiver up for 50 minutes and then turn the meter switch through each position according to the manual and write the readings down. The valve testing went really well also; thanks to the British Valve Adapter I built last year. All tested in a tight cluster in the upper 70’s on my Tube Tester. NOS valves, brand new, test consistently in the upper 80’s by comparison.

Finding all the Bias Resistors to check was another matter. Canadian Marconi Company went the route of consolidating nearly all small components related to the valves on Terminal Boards remotely located from their respective valves to make access easier, sort of.

As you will see in the first two photos, Capacitors and resistors frequently share common terminal sets and then additional capacitors get fitted next door, so access for replacement gets limited. Components on adjoining boards can also overlap, further challenging access. Then the next BIG wrinkle surfaces.

75 plus years ago, electronic components were large and lots of space was needed in a chassis to mount them. The spread between terminals on these boards is exactly 2.0 inches. That means the total length of a new resistor, or capacitor, tip to tip on the leads and the component body included was very likely 3 inches. The component could be tied to the terminal posts, soldered in place and the leads trimmed easily. To replace one of these components today, you are lucky to find any with total length greater than 2.5 inches and sometimes only 2.25 inches. Next to no wiggle room. One has to be very careful planning to work out.

What I did discover, however, is that CMC mounted these Terminal Boards of small hollow steel tube standoffs about one quarter to three eighths inches long. The base end is essentially a hollow tube rivet that gets fastened to the chassis and the other end is threaded to take a slotted, round head machine screw and external toothed lock washer to mount the board. Removing the screws, hopefully, should allow the boards to be carefully manoeuvred a bit to gain a little more access to components needing replacement.

The last wrinkle was I could not find the R20D Bias Resistor anywhere for valve V1B. Checking Allan Isaacs work in England on these receivers, I discovered he could not find it either. I put a call out for help and Jacques Fortin eventually replied, complete with photos to show me this resistor and a related Grid Leak Resistor were actually mounted on a tiny little terminal strip directly underneath V1B at the front of the receiver. The Grid Leak Resistor can just be seen, left centre in the last photos with the Green, Black and Orange bands painted on it. The all-important R20D, Bias Resistor is hiding directly behind this one, completely inaccessible without performing a 2nd to 4th Echelon Repair.

So now I have all the initial data for the Main Set Receiver and have crafted a spreadsheet to log it all in. Next step is to repeat the process with the Remote Receiver, so I can compare notes between them.

David

[David Dunlop]

You may have noticed a lack of postings lately. Some of that is certainly due to Life getting in the way of Hobbies from time to time, but in this instance, the bulk of it is simply me, having to shift gears from a ‘Mechanical/Physical Restoration Train of Thought’ to getting my brain wrapped back around the actual electronics of the project once again. I have been away from that for a year or so now and it shows. Sketchy surviving 2nd to 4th Echelon Documentation for the 52-Set does not help much either.

With the receiver portion of the project, I do have the benefit of three on hand. The Remote Receiver is performing very well and has become my benchmark to compare the Main Set receiver to, in the course of getting it back up and running. Parts of the Main Set receiver are working well. Others barely. The net result is lots of controllable static audio output. End of story.

The third receiver is the Parts one. Useful for comparisons to the other two.

Most of my time recently has been spent designing Spreadsheets on Excel to log data into, as I collect it from the Remote and Main Set Receivers. The general plan is to log as much information as I can from the Remote Receiver and then compare the same data from the Main Set Receiver to try and narrow down significant anomalies for more detailed investigation.

So far, all valves in both sets have been tested and the Meter Readings of each receiver recorded, along with the relevant resisters in the meter circuits. The valves are all rating as new and several resisters in the meter circuits of the Main Set Receiver will need replacement.

I am now completing a pin-by-pin analysis of all the valves in the Remote receiver for both Voltage and Resistance measurements. That work has been done with the exception of V1A and half of V1B. These two sockets are hiding up behind the 8-Pin Connector assembly, which will have to be unscrewed from the chassis and swung away to complete the tests.

Then I can repeat the process with the Main Set Receiver and narrow down significant variations for a closer look.

While doing this work, I was chatting with Jacques Fortin and he asked if any of the receivers had Modification Instruction 6 Performed on them. I had forgotten about this one. It was issued 24 April 1959, and involved replacement of the 10 original 100 uuF Trimmer Capacitors in the IF, BFO and Detector stages of the Receiver.

The originals, a semi-fixed 5-100 uuF capacitor were found to be defective and were to be replaced with a newer improved variable, air dielectric 7.5 to 99.9 uuF capacitor.

The distinguishing characteristics between these two sets of variable capacitors visually, is the originals had a flat zinc plated finish on the tuning shafts and locking nuts and the shafts stuck out beyond the locking nuts about one quarter inch. The new replacement trimmers have a bright nickel finish and the shafts sit flush with the locking nuts.

The Modification Cards in my Remote Receiver and Parts Receiver confirmed the change was done in 1961 on the remote Receiver and never done on the Parts one. The first two photos attached show the originals in the Parts Receiver and the second set of photos show the upgraded capacitors in the Remote Receiver. C7A to C7H can be found in two banks of four at the back of the chassis. C7K and C7J are found, left to right, at the front of the chassis on the extreme left directly above the retaining clamp for valves V1G and V1H. No letter “I” was used in the coding system for these trimmers.

I thought I would post this information in case anyone has a 52-Set Receiver with no Mod Card. They can at least now determine if their receiver was modified or not.

David

[Mike K]

Hi David

I am not a radio tech by any stretch but the normal method of testing tube receivers was to check each stage at a time . They used to use a VTOM , VTVM or oscilloscope and compare the readings of each stage to the figures found in the service manual. Maybe you could measure the stages of your receivers and compare them and get an idea of where the problems are.

[David Dunlop]

Good Evening, Mike.

I too am about as far away as one could ever get from being a qualified radio tech. My entire training was a one Year Electrical Shop Class in Middle School back when Spark Gap Transmitters were still a popular means of delivering the Evening News!

You are quite right, however, that a logical troubleshooting search can be accomplished following the basic Block Diagram flow of the major circuits from the R.F. Amplifier at the Aerial end to the A.F. Amplifiers at the Loudspeaker/Headphones end. The valve and component layout within the receiver chassis follows this flow visually, in a very good manner. It is the 2nd to 4th Echelon Maintenance Manual that I find very unnerving.

I have the Wireless Set No. 19 Mk III 2nd to 4th Echelon Manual as a comparison. It is a brilliant work. It starts with a brief introduction to the set; a massive Table of Contents (the manual is some 400 plus pages) and a list of test equipment required and support items to be fabricated. Then off it goes with a very logical step-by-step analysis, with relevant disassembly instructions when and where they are needed. It is a very good manual for step-by-step work and how to do it.

By comparison for the 2nd to 4th Echelon Manual for the 52-Set, there is no list of test equipment needed and no table of contents/index at all. The first five steps in the manual are:

- Meter Calibration.
- Switch Connections (pages of exploded diagrams of switch connections).
- Cleaning the Crystal
- Dismantling the Flick Mechanism,

And then suddenly you are in:

Alignment and Specification Testing:

I.F. Alignment.

If you plod well into the manual, about two thirds, you eventually discover 12 Point to Point Voltage and Resistance Charts for the Main Set Components, providing the factory original electrical specifications for each point to point test.

I am currently replicating three of these charts for the two receivers I have available. There are a couple of more for point to point tests from the various valve pins to either switch contacts, or terminals on the 8-Pin Connectors. I hope to replicate them as well.

Time consuming, yes. But what else is there to do with Covid running amuck? Sigh! It should mean I have become very familiar with the innards of the receiver when I am done and given the electronics sections of my brain a good dusting off in the process. My hope is I end up with a set of factory standards and a set of specs from a fully working 75-year-old receiver to compare those to. That would give me an acceptable range of specs the receiver is happy to work within. Then I can see how the specs from the non-working receiver compare, so that I can narrow down exactly what has to be replaced. The more parts I can order in one shipment from a supplier these days, the better.

As long as I don’t grow cataracts in the meantime, I am laughing.

Stay safe Mike!

David

[David Dunlop]

I have been looking at my Remote Receiver now since January of 2018, but only just saw the upper mounting hardware on it this last weekend.

When it arrived in the mail, the two upper ¼-inch hex bolt assemblies were installed from the outside of the case inward, so the lock washers and hex nuts were on the panel side of the case. This had always looked OK to me as the heads of the bolts were on the outside and did not protrude any significant amount. I looked streamlined. It looked nice.

Whenever I needed to work on the Remote Receiver, I removed the four sets of mounting hardware and pulled the receiver out of its case, worked on it and put it back. For the very first time in over three years last weekend, I had to check something quickly on the Crystal Calibrator, so decided to simply remove the upper front panel of the receiver to have a look. I could not do that. The two ends of the upper panel, once it was unlatched, kept hanging up on the upper mounting hardware, and no matter what sort of angle I attempted with the upper panel, it would not come free. So I locked it back in place and had a closer look. And eventually, I saw for the first time what I was looking at.

The cut-outs on either end of the upper front panel of the receiver are designed to clear the thinner heads of the ¼-inch hex bolts, NOT the thicker and longer shank ends. Note the attached photos. That is also why the upper hardware holding the main set receiver in place in the Carriers No. 4 also has its hardware feeding towards the Supply Unit on each side.

It took three years, but I finally understood the design.

David

[David Dunlop]

Not a very productive week at all in so far as the 52-Set Project goes. I did get another spreadsheet drawn up for logging the Voltage Values deemed relevant from all the receiver valve by Canadian Marconi Company in the 2nd to 4th Echelon Maintenance Manual, and have now got those values from the Main Set Receiver logged in. Still a lot more of this sort of analysis to finish, however. I did find one interesting thing through all this though.

Another oddity has surfaced related to Valve V2B.

All the valves in the 52-Set Receiver utilized directly heated filaments and this is typically provided directly from the battery voltage used to power the set. In this case, 12 Volts DC. With North American valve production, these filaments, or heaters, are connected to Pins 1 and 2 on the base of the valve. The valve pin numbering system is different in the UK, so going at least as far back as the Wireless Set No. 9 Mk I*, CMC converted the valve pin numbering system used on the British Based Valves to North American standards, to avoid any confusion on the assembly lines. So for all the valves in the 52-Set, then, Pin 1 will be the Plus side of the 12 Volt Heater circuit and Pin 2 would be the return side.

So one of the voltage checks for the 52-Set Receiver is to see that the filament/ heater circuit is working and to do this, you take a reading from Pin 1 to Ground on all of the valve sockets to confirm 12 Volts is present. If you get nothing on your meter, the Pin ! circuit is open and the valve has failed, or the heater circuit ahead of the valve socket you are testing is broken somewhere.

During this test process on the Main Set Receiver, I arrive at Valve V2B and got a reading of ‘0.004’ on my meter. Odd, because I had just tested all the valves a few days ago and this one was working perfectly. Even odder, because I am looking at the valve and can clearly see the heater glowing happily away at the top of it. We can even kick it up another notch! This has been the reading I have been getting from Pin 2 on all the other valves up to this point. So I check Pin 2. I get a meter reading of 12.71 Volts, which is exactly what I have been getting from Pin 1 on all the other valves, and which is a match to the output voltage from my ZE-11 Remote Supply Unit.

When I look at the wiring on the bottom of the V2B valve socket, it is all undisturbed, factory original soldering. Mystery solved. Somebody made a mistake on the assembly line wiring up this particular socket. In fairness, the mistake is no big deal as the Heater Circuit is isolated from all the others in the receiver and the heater will work happily wired either way. What got really interesting, however, was that when I got around to the same testing on the Remote Receiver several days later, the same result was found. At that point, I also decided to check the spare receiver. Same thing. All factory original soldering and all soldered with Pins 1 and 2 flipped.

There is no logical reason for wiring these two pins in this way deliberately, so my suspicion is that this was likely an error in the production line assembly instructions drawn up for the work station involved with wiring in the heater circuit connections for the V2B socket. The error was missed and never found and corrected.

Interesting what one can discover 75 + years after the fact.

David

[David Dunlop]

Not that much of interest going on with the 52-Set lately. I have pretty much finished all the test measurements for the Remote and Main Set Receivers and can finally sit down and compare the two between each other and the specifications in the manuals.

Out of curiosity, I did do some random tests on several capacitors and resistors in the Spare Parts receiver and was pleased to discover they were all still within original specifications. With that in mind, I have decided the next step in this project will be to strip the Spare Parts receiver of all retrievable components, starting with the four Tag Boards holding the majority of the resisters and capacitors and work my way through it until just the chassis frame is left. A couple of extra plastic storage bins should be enough to get all the parts, including the two front panel sections put safely away.

This will serve a number of purposes. I can reuse original parts were appropriate before having to source modern replacement look alikes, which are getting more and more expensive with minimum order amounts and trans border shipping, and also free up a huge chunk of shelf storage space where the three wooden accessory boxes for the 52-Set will eventually reside.

David

[David Dunlop]

I was in the local Canadian Tire Store a few weeks back looking for replacement Hoover bags and happened to shortcut through the paint section.

In doing so, I spotted two cans of this paint sitting on the top shelf of the display. It was the first time I had ever seen a spray can of luminous paint and I was even more intrigued that it was enamel based, unlike the latex based ones I have been working with on the 52-Set. Even better was the fact the colour was the same Neutral Green, using the same phosphors as found on the latex paints, and it was recommended to be used over a white base coat, So I bought one of the cans.

The Rustoleum Stock Number for this paint is ‘272695’, if anyone is interested in tracking it down, and it is simply called, ‘Glow in the Dark’.

Nothing specific for its use at the moment, but the project is far from over yet, and it never hurts to have options where possible.

David

[Mike K]

Hi
Just curious about how you test the old higher voltage capacitors .

I have a D/I\D marked capacitor tester finished in khaki green, dated 1945. It performs well with a green tuning eye tube for visual indication .

[David Dunlop]

Hello Mike.

Interesting you should ask.

About 30 years ago, I ran across a Solar Manufacturing Corporation, Model CF CAPACITOR EXAM-ETER, with its matching calibrated manual that was headed to the Landfill. It was missing its test leads, which turned out to be critical for the proper operation of the instrument and it was not until 2019 that I ran across a chap in the States who also had this kit with leads. He gave me the specifications for the leads and I was able to fabricate a set.

The tester was made in 1946, vacuum tube driven and is capable of testing for Capacitance, Electrolytic Capacitor Leakage, Insulation Resistance, Resistance, DC Voltage up to 600 Volts and AC Voltages from 5 to 50 Volts.

The claim to fame for this tester back in its day was the ability to test capacitors in situ reliably, without having to disconnect them from their circuits to avoid biased readings from the related circuitry. I hope to be able to finally check out its capacitor capabilities with the 52-Set Project.

Currently, I have a basic multimeter able to provide capacitance readings and recently bought a Proster DIGITAL LCR TESTER Model BM-4070 to see what it can do. So far so good although in tight spaces, I find its probe heads much too large and clumsy to work with. I am interested to see how the Solar tester will compare to the modern kit when I really get into it.

David

[Mike K]

Is this the unit ? https://www.youtube.com/watch?v=Wje6Z2eOWng

[David Dunlop]

Affirmative, Mike.

David

[Bruce MacMillan]

The Proster and the Solar measure two different parameters. The Proster is good for measuring ESR (equivalent series resistance) which basically tells you if the electrolyte in the cap has dried up. The Solar can measure leakage at high voltage levels. Using the power factor you can calculate the esr as well. I would be more concerned with leakage as it can sometimes damage components like that nasty cap in the WS19 that takes out T2.

Still both are good tools to have on the bench. When the repair shop I worked at shut down I aquired a Sencore LC102 which does both.

[Chris Suslowicz]

I use a Peak LCR meter for checking values, and the companion ESR unit for series resistance. For electrolytics there's a 1950s-vintage "Reforming Unit, Electrolytic Capacitor, No.1" which will handle up to 350 volts or so, after which it's a matter of "drag the bench supply out" if I need to re-form higher voltage electrolytics (take them up to 350 on the reforming unit, then finish with the bench supply).

For non-electrolytics (waxed paper, paper in oil, mica, etc.) I have an Ionization and Breakdown Tester that will go up to 12kV (or 6kV AC). That's just used for Pass/Fail testing though - you can't fix those types of capacitors.

(The Peak units are semiconductor, so care is needed when using those - making sure there's no charge in the unit under test before connecting up is very important!)

Chris.

[David Dunlop]

The slow, but steady, disassembly of my Spare Parts Receiver 8349 is underway and it is already revealing some interesting bits of information.

David

[David Dunlop]

These two retaining brackets cannot be found in either version of the Master Parts List for the 52-Set Receiver. Odd, because they are clearly designed to be replaceable, if needed.

For lack of a description, I have simply referred to them as ‘Valve Shield Retaining Brackets’, as their intended purpose is to keep the shield assemblies for the two horizontal rows of valves in place.

David

[David Dunlop]

The two vertically mounted valves in the lower left front of the chassis also have their shield assemblies held in place with a retainer. This one, however, can actually be found in the Master Parts List as a PADS, Valve Retaining ZA/CAN 4625 It is a rectangular steel plate with a grey felt pad glued to the bottom of it and a central slot cut half way into the middle of it.

This PADS slides over a threaded shaft and it fastened in place with a wing nut.

With the lower receiver front panel now removed, I was able to take a closer look at the threaded shaft used to fasten the PADS in place. It turns out to be nothing more than a Slotted, Truss Head 10-32 x 1-inch NF Machine Screw threaded all the way into a hole at the apex of its mounting plate, and then soldered in place. So if the one on your 52-Set receiver is damaged in any way, it can be replaced.

David

[David Dunlop]

This package arrived in the afternoon Post today.

I decided to go with the Hayes Paper product after some lengthy web reading as this company was consistently in the top section of all reviews, their own website has a very good section on how to best use this product, including the pros and cons of various sealers and relaxing agents used to get q good fit of the decal over raised surface details.

Eventually, I am going to have to completely refinish the front panel of the main set Supply Unit, which will include a full new set of decals. Now when the time comes, I can roll right into it without worrying about being able to source the necessary bits and pieces.

David

[David Dunlop]

This morning I was able to remove all the loose switches from the front of the chassis. I did not want them continuing to swing and bang about while maneuvering the chassis around trying to work on the removal of other bits.

I can see already I will be needing more desoldering wick real soon.

Once the removed parts are cleaned and checked, I bag them with an ID Sticky Note and if the part is compatible with any Canadian 19-Set Mk III parts, I make note of that as well. It slows things down a bit but at least in the future, I will know exactly what I am looking at during a parts search.

I will start on one of the Tag Panels at the back of the chassis next.

David

[David Dunlop]

I was in the mood, and had the time, to remove one of the Tag Boards from the rear of the parts receiver chassis this morning. If any of you are familiar with Allan Isaac’s restoration work in England on the 52-Set receiver, this is referred to as the ‘ER Tag Board, and was located in the empty section of chassis in the lower right section of this photograph, below the V2B socket, where the two small mounting posts are now visible. If you refer back to Photo 1 in Post #580, you can see this board as originally mounted on the chassis of a receiver.

The work went rather well with just a pair of needle nose pliers and the soldering iron to remove the relevant leads.

A screwdriver was then needed to remove one grounding strap and the two mounting screws for the board.

David

[David Dunlop]

After a careful search of the Master Parts List for the 52-Set, this turns out to be the official part name for the Tag Board ER in my previous post.

The two attached photos show this Panels, Phenolic now free of the receiver chassis. The three pieces of masking tape on the rear of the panel are simply an orientation reference for the panel should I not see it again for several months, and to hold the mounting hardware in place.

For some reason, when I first turned the panel over, I was surprised to see the wire lead in place across the top of the panel. Then it slowly sank in that all such panels in the 52-Set would have been stand alone, sub-assemblies during the manufacturing process. Components would have been fitted to the various panels as appropriate and then these completed panels would have arrived at various stations on the assembly line to be wired and mounted onto the appropriate chassis assemblies.

If you look closely at the rear view photo, you can see where the two capacitors were mounted to the panel at the second pair of tags from the left and the last pair at the right end. The capacitor leads were fed down through the tag panel holes, and then wrapped back up around the edge of the panel and back around the upper ‘T’ terminal of the tag. An interesting approach, as this would have physically held the capacitor firmly in place and allowed the station operator a free hand in soldering the capacitor in place.

The other interesting thing I noticed is the offset mounting holes. This allows the panel to be mounted on the chassis, one way only, further reducing the risk of errors on the assembly line.

On the front side of the panel, where the unoccupied tags are seen, you can see a black, circular C.M.C. Inspection Stamp, and below it a small blob of blue paint. I have seen this blue paint blob referred to in other CMC documentation as proof that a particular component works to required specifications, so I am guessing the black inspection stamp simply confirms the panel was properly assembled.

While I think of it, does anyone know if there is a standard, or accepted way of numbering the tags on one of these panels? They all seem to be referenced by the number of terminal tags present and these are always in even numbers. The even numbers makes sense, but where and how does the numbering typically run?


David

[Mike K]

They are unusually small resistors for use in a valve set.