Wireless Set No. 52 Canadian - Project

[David Dunlop]

With any luck at all, this collection of items, along with a few yet to be sorted, will all come together to create a working replica of the actual Operators Lamp for the 52-Set.

It seems the cargo ship full of all the originals has yet to be raised from the depths.


David

[David Dunlop]

I am not certain how many other 52-Sets might be out there being brought back into operational condition. It can be a challenge in terms of available information and every little bit helps.

In getting back to work on my Sender this weekend, I ran across a little oddity regarding the metering circuits in the 52-Set.

On Page 127 of the Operators Manual, there is a Table of Voltage Readings provided for the Sender. For HT1, depending on Sender Settings, the range of values is from 290 Volts DC to 310 Volts DC. This initially struck me as interesting, but odd. The upper scale of the 52-Set meter is from 0 to 300 Volts DC only. I then noticed the voltage range for HT1 stated on the Table in Page 127 was 0 to 600 Volts DC. If this information was correct, then when reading Sender HT1 values on the 52-Set Meter, the indicated values on the meter would have to have a ‘x 2 Factor’ applied to them, and the metering circuits would have to be set up accordingly.

When running a no load test of the Sender (no valves present), my HT1 reading was a solid, steady 150 Volts DC. Apply a ‘x 2 Factor’ and I get a perfect 300 Volts DC, which I was quite pleased with. I ran this information by Jacques Fortin and he checked the documentation and circuit diagrams. Sure enough, he found no evidence either of this metering design being mentioned in the manuals, and did confirm when the Receiver Meter Switch is on SENDER and the Sender Meter Switch on HT1, a pair of 600K resisters are brought into the circuit in series giving it a 600 Volt rating as per the Sender Voltages Table in the Operators Manual.

I am now going to start reinstalling the valves back into the Sender one at a time, starting at the front end of the block diagram. With all of them in place originally, one of the operational Tests for the Supply Unit had the two dynamotors running with 300 Volts HT1 just nicely, the next test up, however, had a massive load hit the dynamotors on startup and the indicator lamps nearly went out. And the HT1 reading was an alarming 180 Volts DC.

More as the saga unfolds.


David

[David Dunlop]

I pulled the Sender back out of the Carriers No. 4 this morning to install V6A, the Voltage Regulator and see what happens with the Sender when everything is powered back up.

Getting the Sender back into the Carriers No. 4 has always been a challenge, ever since it arrived. It wants to hang up at the last half-inch or so and ends up having to be pressed home in the upper left corner, and then wiggled some more to get the upper mounting bolts installed.

As I was swinging the Sender up onto my work desk and turning it around to install the V6A Valve, something caught my eye for the very first time with the PL2A 8-pt Connector mounted in the upper left rear corner of the Sender chassis. The MIC Terminal in the lower right corner of PL2A was bent upwards. So much so, in fact, that the corresponding Spade Terminal for this connection on the Carriers Plug was sliding underneath the MIC Terminal and pushing it upwards to the point where a crack had developed in the Bakelite body of the Connector, between the MIC and FAN Terminals. This is what has been causing the poor fit of the Sender in the Carriers No. 4, and who knows for how long.

The three photos today show the extent of the upward shift of the FAN Terminal and the crack to the left of it.

Now I just need to figure out the best cure for this problem, which will also successfully cancel any future travel plans for the crack that has developed. It does not look like it has caused any significant damage to this point in time.

I think I have said it before, but there is never a dull moment with this project.


David

[David Dunlop]

After studying the damage caused to the MIC Terminal of the PL2A Connector for a while, I decided a full disassembly of the connector was not necessary and that the terminal itself could be repositioned correctly with a little patient TLC. The trick would be not to try and fix everything at once by just trying to bend the entire terminal back down to where it should be located.

I started by inserting a medium sized slotted screwdriver head into the gap in the terminal and locking the blade up against the base of the terminal, directly below the round head slotted screw. Then I gently bounced the lower terminal blade a number of times until it was lined up with the others in the lower row of the connector. This left an excessively wide gap in the terminal, which then needed to be closed up by getting the upper terminal blade lowered somehow.

I found a combination of pinching the terminals together with my fingers and alternating with a pair of adjustable pliers worked well. After a few such pinches, I would have to stop and repeat the screwdriver move on the lower blade of the terminal to keep it back where it should be, but after about 20 minutes work of alternating the pinching and lower blade adjustment, I had the MIC Terminal looking just like a couple of the other terminals on the connector with wider gaps.

The proof was in trying to reinsert the Sender back in the Carriers No. 4 and this time it went a lot more smoothly than it ever has before. Getting it installed is now comparable to installing the Receiver and the Supply Unit, so one more unexpected item has now been fixed with this 52-Set.

In the attached photo, you can see how much better the MIC Terminal lines up with the other in the PL2A 8-pt Connector.



David

[David Dunlop]

The fact there are so many pieces to this project can be very daunting at times, but every once in a while this proves to be a blessing.

I have been spending the last few weeks focused on sorting out the Sender electrically. A strong part of this motivation is the simple fact I do not have a back up Sender assembly I can turn to if anything serious fails in the one I have on hand. Should that happen, I have a vey large paperweight sitting on my bench.

The second, related motivation is the fact I experienced a massive load hitting the Supply Unit when I first applied it in full power mode to the Sender, suggesting something was indeed seriously wrong somewhere, and that it was very likely in the Sender.

In the process of considering likely candidates for a problem in the Sender, I was looking closely at a couple of transformers as possible candidates this week and going through the Parts Lists to glean any useful information held therein. While doing so, I thumbed passed the two Rotary Transformers when a detail regarding the MG1A unit struck me. Its input rating was 12 Volts DC at 7.5 Amps. That prompted me to check its big brother MG2A directly below it. Its input rating was 12 Volts DC at 25 Amps. I was actually quite shocked, no pun intended.

I then checked TABLE VII, CURRENT DRAINS on Page 20 of the Operators Manual and there it was, 31 to 35 Amps in Low to Medium Power when the Sender was active in the Set. I had completely missed that point in getting overly concerned about potential problems with the Sender itself. I am currently running the 52-Set on just one CPP-2 Power Supply with a maximum output of 12 Volts DC and 22 Amps.

I am not that impressed with myself this morning, but still glad I discovered this when I did. Now to get the 2nd CPP-2 Power Supply I purchased from Brian Asbury last year paralleled into the system today and try again.


David

[David Dunlop]

When my second CPP-2 Power Supply arrived, I did a preliminary inspection and cleaning, tested it for working status, and that was it. I still have not yet performed a detail cleaning, but that will come in time. The important thing at this point was to ensure a close match in output between the two units. These power supplies come with a 6-position rotary switch that allows the supply to be set at various points between roughly 10 and 15 Volts DC. I was quite pleased I could get both of them sync’d at 13.5 Volts DC output to start.

The first photo has my original CPP-2 running with the amber indicator lamp and the new one with the red lamp. The second photo shows the input voltage at the Supply Unit after a short warm up.

The third photo shows the meter on the Receiver set to LT and reading a steady 12.0 Volts DC.

In the fourth photo, I have set the metering up to read the HT1 voltage being delivered to the Sender. This comes exclusively from the MG1A Dynamotor. Under a normal load condition in the Sender (all valves in place and not transmitting) this value would be 300 Volts DC. As you can see the meter reads a steady 160 Volts DC, which for the purposes of reading HT1 values, gets a ‘ x 2 Factor’ applied giving a no load value of 320 Volts DC, which is within the specified parameters in the manual.

The last photo is just a look at the full 52-Set idling with no load and its Supply Unit running perfectly in Send Mode. Something of a milestone moment after sitting idle for a number of decades.

Since the electrical testing I performed a few weeks ago showed no red flags up to the V7A (813) Power Amplifier, I am now going to recheck the Voltage Regulator V6A, and three 6V6G’s (V5A, V5B and V5C), the Master Oscillator Doubler, Amplifier Doubler and Intermediate Power Amplifier respectively, reinstall them in the Sender and run the Supply Unit again with them in place. Hopefully, there will be no surprises.


David

[David Dunlop]

A number of learning curves for the 52-Set are converging in my head at the moment and I am not certain I like it.

I have chatted with a couple of current users for the 52-Set and a former operator to learn what they have experienced and have been going through the manuals a number of times to wrap my head around it all. Interesting times.

One thing I have discovered is that there is apparently quite latitude in HT1 voltages displayed on the set for the Sender. The nominal voltage appears to be 285 Volts DC and one current operator with a Mains AC Supply has his running constantly at 285 and the set is quite happy. The manuals give a test range from roughly 260 to 310 Volts DC with a 10 to 15 percent variance for any given value as quite acceptable. Virtually all of my readings for HT1 fall into this range, which is challenging when trying to use the values for serious faultfinding.

Pin 4 circuits on the V7A (813) are still too high when the Sender is in RT Mode, but just fine in MCW or CW. Pins 1, 4 and 6 on V1J (ARP-3) in the Sender have a similar performance, so I am mapping these circuits out to identify all the connected components for a closer look.

In the meantime I have taken the Operational Tests as far as I could and so far and everything that is supposed to work and check out is doing so. I have also decided to run the NET and SEND Tests for a minute each, a couple of times a week. The NET gives MG1A, the 300 Volt HT1 Dynamotor a workout and sends electrons through those circuits. The SEND Test fires up both the MG1A and the MG2A Dynamotors thereby activating both the HT1 circuits and the 1,200 Volt circuits. So far, no loud noises, smoke or flames.

By the end of July, I will pull the Sender from the Carriers No. 4 again, pull all the valves, again, and retest the three odd circuits. I am curious to see if any of the bad readings will change, one way or the other. In the meantime I get a chance to do more reading and thinking.

In order to continue with the Operational Tests for the Sender, I need a Dummy Load to feed the 52-Set into. Turns out the 2nd to 4th Echelon Work Instructions provided a very nice diagram for constructing such a Dummy Load. The only risk was being able to find a 150 Watt Incandescent light bulb in todays world, but as luck would have it, the local Lowes still carries them I picked one up first thing this morning and now have an appropriate Dummy Load on hand to continue the Operational Testing. A good friend advised me his house still has several porcelain socket fixtures identical to the one in the original Canadian Army illustration but his wife nixed the idea of removing one and giving it to me, so I also picked up a modern, porcelain equivalent at Lowes.


David