Wireless Set No. 52 Canadian - Project

[David Dunlop]

Part of my tool kit for the longest time was a small inspection mirror, about the size of those used by Dentists, but with a white nylon head, rather than metal. Had it close to 30 years before the nylon head started to perish and one day, while in use, it fell apart completely.

Found a replacement today at Canadian Tire. A little bit larger diameter mirror head but the handle is telescopic and the head has 360 degree swivel capability.

I picked one up to get a closer look at the three machine screws holding the upper BAND Switch and FREQUENCY ADJUST Switch plate in place. Its a very tight work space in that area of the receiver chassis, even with the upper front panel plate removed. I was delighted to discover the three machine screws are fastened directly into the top folded edge of the lower panel plate. No hex nuts and lock washers to deal with. Big thanks to the original designers of the 52-Set for that stroke of genius. That basically leaves a single soldered aerial connection to deal with, although I still need to remove the two aforementioned switch knobs to check for any shaft mounts fitted to the switch panel.

David

[David Dunlop]

Over the past few days, I have been able to remove the damaged BAND and FREQUENCY ADJUST Switch panel from my Main Set Receiver and replace it with the undamaged one from the backup receiver. In the process, I also took the time to examine all the Valve Shields and Caps in the two units and apply the best of the lot to the Main Set receiver.

All this was not done without incident, however. The issue in this situation turned out to be the Band Selector Switch knob on the backup receiver. It simply did not want to come off the switch shaft and there was nothing at all to leverage against, other than the panel behind it that I needed…undamaged. I tried everything I could think of for the better part of an hour and a half and could only gain half the distance needed to get the knob off the shaft.

This turned out to be a VERY interesting little switch. It is actually mounted on a sub chassis on the right hand side on the main chassis assembly. The knob shaft passes through a small support collar on the switch panel and straight back about 3 inches to a support sleeve about an inch and a half long. Immediately behind this rear support, the shaft ends in a brass gear, part of a two gear right angle drive that feeds the selector action to the actual switch on the right hand side.

After studying this arrangement for a while, I realized I could loosen the grub screws on the rear support sleeve and brass gear on the end of the knob shaft and slide the entire shaft straight out the front of the panel. I could then remove the offending knob and reinstall the knob shaft. Almost.

Things proceeded well until I arrived at the last item: the brass gear on the end of the shaft. Seems the last dear soul who worked on this particular item did not feel the grub screw had been secured safely until the Bristo Key had been turned a sufficient number of times to completely round out the inside of the grub screw. And then the daft twit probably continued to turn the key further, while consuming a large pot of coffee! Sigh!

I really hated having to resort to it, but out came the hack saw and off came the front 1.5 inches of shaft with the offending knob still attached. Even in this new free state, I had to lock a pair of vice grips onto the shaft stub and gently lever the knob with a hammer claw to finally pop it from the shaft undamaged. Interestingly enough, after careful cleaning and inspection, this knob slipped quite happily onto any other shaft available, but did not want to go back on the piece of the one it had just been pried from.

I was feeling pretty bummed about having to trash an otherwise good shaft assembly, but when talking to a friend last evening, he advised he has a box full of NOS switch shafts and can easily enough find one I can use to replace the one I had to cut. I will just have to drill out the damaged grub screw from the brass gear, carefully, install a new grub screw and it should be good to go.

One other small discovery was that when I removed the outer most 12SC7 valve from the Crystal Calibrator, I discovered the central alignment pin was missing and the inner glass envelop stub was cracked. So that valve was clearly not working anymore. I found the pin stub still sitting inside the valve socket, fished it out and installed a new 12SC7.

David

[David Dunlop]

I almost forgot to pass along a soldering tip in case anyone else needs to do soldering work on the 52-Set Receiver Aerial connector.

The soldering terminal in question is less of a typical terminal and more an extension of a small piece of heavy sheet steel. It sits on top of a much larger, vertical piece of sheet steel, same gauge as the main receiver chassis steel, to which the two aerial terminals are fitted, along with the right hand side Clip for the ARRESTERS, PROTECTING, GAS GAP. In fact, the accumulation of steel at this point is so thick, a 1/8-inch thick steel spacer is fitted between the left side ARRESTERS Clip and the back of the sub panel to bring both clips parallel to one another. The net result is the creation of a massive heat sink for the aerial connector, which needs to be taken into consideration for any soldering work.

My soldering station iron, set to its normal 350 degrees C, only generated enough heat to let the soldering tip skate about on the surface of the solder. I had to haul out the trusty vintage WELLER HD Soldering Gun to get the job done.

Also, I have no idea just how much heat the glass envelop of the Gas Gap Arrester is designed to handle, so I removed it from the clips prior to working on the terminal connection. Apart from the unknown heat risk, the right hand clip sits directly under the soldered aerial terminal and there was a good possibility any solder dripping from the terminal could wick into the space between the arrestor end cap and its clip.

As it was, it took about 5 minutes after completing the work before either aerial terminal or the right hand Arrester Clip were comfortable to touch.

David

[David Dunlop]

While looking up this item in the Master Parts List for the 52-Set today. I discovered that the Wing Nut used to secure it was not listed at all. Which was interesting because two versions of this Wing Nut (3 in total) are used in the 52-Set in two separate locations.

The first photo shows the NUT, ANF, Steel, Wing 10-32 version used to secure the titled PADS in the 52-Set Receiver.

The second photo shows the NUT, ANF, Brass, Wing 10-32 version used on the input terminals of the COIL, Aerial Tuning No.2A. There is an identical terminal on either lower side of the Coil Case, the output transmission connector from the Sender can be attached to, depending on the orientation of the Coil on the 52-Set Carriers No. 4.

I wanted to post this information in case anyone was looking for it.

David

[David Dunlop]

As I have been cleaning up the panels on the two 52-Set receivers, I became more and more curious regarding how much luminous paint had survived over the years and how much might have been replaced when the receivers went in for servicing. I have no idea of the history of the Main Set Receiver, but the Remote Receiver has an added, white decal below the Meter that states “NON-LUMINOUS DIAL” that I have assumed related to the Meter, as it is a different design than the ones on the other two receivers. So this receiver has definitely been in for some level of overhaul in its service life.

I did a little research recently to refresh my memory about Phosphorescent Paint, which confirmed the activating energy for the phosphors is ultraviolet radiation. And as luck would have it, our daughter’s Black Light was still tucked away in a corner of the basement. And it still worked!

Unlike Radioluminescent Paint that glows continuously until the phosphors burn out, the Phosphorescent Paint used on the 52-Set and 19-Set panels charges up during the day while exposed to natural ultraviolet energy and in the dark, the glow will last from 8 to 10 hours. Gradually fading away in the process. This cycle repeats itself daily.

I checked the Main Set Receiver, the Remote Receiver and out of curiosity, also my 1944 RCA Wireless Set No. 19 Mk III Cdn. I took three photos of each item. The first is in normal light. The second was taken while charging the Phosphorescent Paint with the Black Light for about two minutes . These second images show a combination of florescence off the various materials on the three front panels, as well as luminescence generated by the Phosphorescent Paints. The third photo in each set is a 12 second time exposure started immediately after the Black Light was turned off. It might be a bit hard to see in these smaller, low Resolution images, but the luminescence is actually quite bright initially but dims off quickly. In complete dark, the eye can see the glow for about 10 minutes. Actually not bad for 75 year old phosphors!

This first set of photos is the 52-Set Receiver. I will post the other two sets shortly.

David

[David Dunlop]

These three photos are of the Remote Receiver.

I was surprised to discover the decal referring to the presence of non-luminous paint was not related to the Meter, but to the fact the Frequency Dial was no longer luminous.

It was also interesting to see where the panel paint had been touched up, which is not readily apparent under normal lighting.

David

[David Dunlop]

This last set is of my WS No. 19 Mk III Cdn, all built in 1944, the same year as the Marconi 52-Set equipment. The Transceiver is RCA, the PSU is Northern Electric, the Crystal Calibrator is Marconi and the Pocket Watch is unmarked.

David