Wireless Set No. 52 Canadian - Project

[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