Wireless Set No. 52 Canadian - Project

[David Dunlop]

I spent a slow, and reasonably careful (more on that later) morning today, cleaning up most of the Sender chassis interior. The sequence of soapy water toothbrush scrub, gentle air gun towards strategically placed paper towels, mild cleaner scrub with toothbrush, rinse, and air gun, is tedious work, not to forget mention of careful drying with Q-tips and more air gun, but the end result is rather pleasing when done.

If you scroll back to the second photo in Post #207, you will see the before image. Oily carbon soot everywhere. Now the phenolic boards are all shiny brown. I can actually see the colour traces in the main wiring looms. The colour code rings on the vertical stack of large resistors can been clearly seen again and all that scary carbon deposit is finally gone from the two large ceramic terminal plates and the rest of the BAND Selector Switch assembly. I will wait until just before reassembly to clean all the switch and relay terminals with DeOxit.

A few more items in the chassis remain to be cleaned, but I am finally over that particular hump and the remainder needs a bit more careful study of how best to position the Sender chassis, while in a disassembled state, to get safest access to the parts that still need attention for cleaning.

David

[David Dunlop]

I mentioned in my last posting the cleaning process today on the Sender chassis was almost uneventful. Well here is what I discovered about the word ‘almost’ today.

Back in Post #280 and Post #281 I had discussed what I had learned up to that point in time about the COUNTERS Coupling Assemblies used in the COIL, Aerial Tuning and Senders PA LOADING Drives respectively. The assemblies used in the Sender are more sophisticated, utilizing a lower Bakelite plate with small pin, and an upper tapered metal plate with a slot the pin slid into. There was also a somewhat mysterious SPRINGS, Coupling Assemblies wrapped along the top surface of the tapered metal plate and snugged up against the pin from the lower assembly. It was clearly there to provide some tension to the assembly, thereby taking up any play, or slack in the coupling, but it seemed a bit to vulnerable to any excessive movement. My hunch, in all respects, was correct.

With the Sender now resting on its back on the worktable and the bottom towards me, I now needed to access the top of the Sender chassis for cleaning. A simple enough thing to achieve I thought. Just carefully lift the Sender, turn it 180 degrees, and lower it back down with the top now towards me. The detail I forgot in all this was I had removed the two small wooden blocks from under the two COUNTERS assemblies to gain access to the phenolic board behind them for cleaning. As I lifted the Sender up from the supporting 2 x 4s on the worktable and started to turn it, I saw the right hand COUNTERS assembly dip down and swing suddenly. That was alarming enough, but at the same time I heard a very heart stopping ‘TWANG! Tinka-tinka-tinka-tink’, and then silence. By now, the right hand COUNTERS was actually touching the Bakelite below it and the two parts of its Coupling Assembly were clearly no longer aligned with each other. I carefully set the Sender on the carpet and looked for small SPRINGS, Coupling Assemblies that was no longer in place. It was not in the chassis. A first look at the top of the worktable showed nothing, but when I moved the two 2 x 4s, there it was, resting up against the edge of one of them.

The good part of this event was I discovered once the SPRINGS, Coupling Assemblies is removed from the system, the COUNTERS assembly with the attached upper metal coupling plate can be lifted free from the lower plate. That provided a great cleaning opportunity, once my heart rate had returned to normal. I knew this particular LOADING Coil was snugged back to its zero point, so all I had to do was turn the COUNTERS back to all zeros and remount is aligned to its lower plate and replace the SPRINGS. That newfound knowledge means the other COUNTERS will be able to be reset to Zero far more easily than I have thought, when the time comes.

I added a photo of the top plate of one of the COUPLING Assemblies showing the end with the pin sticking through and the SPRINGS against the side of it.

I am sure this will not be the only heart stopping moment in the restoration journey of this 52-Set, but as long and none of the others involve high voltage/amperage, I will be a happy man!


David

[David Dunlop]

I got another bit of cleaning in the Sender chassis done this morning, deep in the lower back section and was able to bring the Sender Tuning Selector Switch back from beneath its cover of oily soot. I was amazed to find the Switch Plate was marked with luminous green paint. I would have thought it was far too dark in that location for such paint to work, unless there is enough glow from the surrounding valve filaments to keep the paint active.

David

[David Dunlop]

I was able to pick up another piece for the Project today.

David

[David Dunlop]

A small bit of work done on the Sender this passed weekend, but highly productive.

I was able to successfully remove the two tubular rivets securing what was left of the TERMINALS, Aerial, No. C1 mounting plate to the Sender front panel. If you refer back to Post # 302, you will see the three mount fragments and the back end of the two rivets. The second photo in Post # 308 shows the two truss heads of the rivets from the front of the panel.

I lined the table of the drill press with an old face cloth to protect the front panel paint and went with a 3/16-inch drill bit to cut back the cinch ring on the back of the rivet, being sure to stop the cutting before the centre of the bit got too close the brown phenolic mounting plate.

It was important to be able to identify these rivets to source proper replacements, so once the ends were cut back sufficiently, I switched to a 7/64-inch drill bit to use on the drill press as a punch pin to try and press the rivets out of the front panel. I was a bit wary of this, as generally speaking, drill press spindles are not built to handle that kind of excessive load, unlike a milling machine spindle. But with some gentle increase in pressure, out they both popped.

Before I had started this work, I had assumed these two rivets were plated brass. As the drilling phase progressed, however, the shavings kept coming up bright, shiny, silver. Once the rivets were free, a quick check with a magnet showed they were actually steel. That was a bit of a surprise as I was expecting aluminum.

In any event, they spec’d out to be truss head tubular rivets, with a 7/32 –inch diameter head. Shank diameter is 1/8-inch. Original length was no less than 3/16 –inch and no longer than 7/32-inch. From what I have read on this style of rivets, length is critical to get the job done without damaging parts being held together.

I am going to go with aluminum replacements, as they are the easiest to work with. Particularly when holding thin brown, phenolic board without crushing it to pieces and I only have one replacement available to work with. As it turns out, I can source sizes at both ends of the possible range I came up with exactly, as well as a 7/32-inch length in the middle of the range. I will order in a selection of each.

Now I just have to find an inexpensive hand tool for setting these rivets. The most promising I have seen so far is a C-Clamp style to tool with several interchangeable heads. I will likely only ever use it a half dozen times or so, so don’t need to break the bank There are some countersunk head tubular rivets I need to replace in this 52-Set Project as well, so I need to look into those next.

David

[David Dunlop]

I found one of these a little while back and it arrived in this afternoon's Mail. a lot more compact in real life than I had imagined for some reason. Would have been nice if the Aerial itself had survived, but I think it might be a relatively easy item to replicate down the road.

Now I just need to find the matching Reels, Cable No. 2 Mk II to go with it.

David

[David Dunlop]

I have been side tracked for the last couple of weeks with the discovery and purchase of a minty Tektronix Type 500A Oscilloscope Cart for the Type 545A Oscilloscope I restored earlier this year. Quite nice to be able to glide the 65 pound scope about the shop now and not have to carry it anymore.

With that out of the way, I was able to return to sorting out the shattered AE Terminal Board on the Sender front panel. Once I had drilled out the two rivets holding the remains of the original board to the front panel, I was able to measure the PCB board bits and found them to be 1/16 inch thick and was able to get an old terminal strip of this thickness from a friend in town.

With the terminals all drilled out of the donor board, I was able to scribe out the dimensions of a replacement for the Sender AE Terminal: ¾ “ x 1-1/4 inch. A 5/32-inch hole was then marked out at the centre of that board, and on either side of that hole, a 1/8-inch diameter hole, balanced on 7/8 inch centre to centre.

I drilled the holes out first while the larger sheet of PCB was easier to work with, and then used a 40 tooth per inch X-Acto back saw I bought years ago for a 1/6 Scale Tiger Tank RC Model project, to trim out the required board. Smoothed up the edges and holes with a set of X-Acto Needle Files purchased for the same RC project and another restoration task ticked off the list.

David