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  #301  
Old 23-04-20, 19:09
David Dunlop David Dunlop is offline
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Default SEMS Fasteners

I have been taking a closer look at the panel mounting hardware on this Sender. A two-part reason for this.

Firstly, I want to know exactly what it is I have on this Sender, and secondly, once knowing that, I want to try and determine what is correct and what is not.

I started by numbering all 31 screws I had removed, on the foam board I transferred them to, and then I spec’d each of them out and recorded the data obtained. Apart from seven specialty screws, all others were 6 – 32 thread cutting of ¼, 5/16. 3/8 or ½ inch lengths.

I made some inquiries about possible specific names for thread cutting screws, in the process of which I stumbled across references to SEMS Fasteners. When I looked these fasteners up on line, it turns out pretty much any screw or bolt can become a SEMS Fastener. This fasteners claim to fame is the fact the shank of the screw, directly under the screw, or bolt, head is machined down slightly thinner than the following thread. A split washer is then fitted in that space and essentially held captive there.

With the exception of the previously mentioned specialty screws and two other in the panel, this type of fastener was what was being used as the panel mounting hardware. When I went into the Hardware Listing for the 52-Set, I found them listed as SEMS Fasteners. The big advantage of this hardware on an assembly line is the amount of time saved at stations where the workers do not have to fit individual screws and washers together before installing them. Both pieces are automatically together.

The other interesting thing in the Hardware Listing was that only two lengths of 6 – 32 SEMS Fasteners were used installing the front panels: 5/16 and 3/8 inch. So the ¼ and ½ inch ones I have present are clearly substitutes. That is a big help at this point.

David
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  #302  
Old 27-04-20, 22:04
David Dunlop David Dunlop is offline
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Default TERMINALS, Aerial, No. C1 ZA/CAN 4716

At some point the front panel of the Sender took a hit on this TERMINALS, snapping the small phenolic resin mounting plate for it. I had hoped it was a simple break that could be carefully glued back together, but no such luck. As you can see, a clean break on the left side but nearly 1/8-inch of material has gone missing on the right side.

Fortunately, an identical TERMINALS is mounted on a somewhat larger phenolic board on the 52-Set Receiver and I have one available on my spare receiver. I will have to identify and source the small plated brass tube rivets used to mount the board to the front panel before I can do the replacement, but at least it is doable.

David
Attached Thumbnails
WS No. 52 TERMINALS, Aerial .JPG  
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  #303  
Old 27-04-20, 22:12
David Dunlop David Dunlop is offline
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Default Sender Capacitor C39A

It looks like the only electrical component that was replaced during the 1966 202 Workshop overhaul was this capacitor. The orange coloured one on the upper right side of the photo. It functions in the PA Bias Circuit as the AF Bypass and is rated at 5 mf and 300 Volts. The original was nearly 1 inch in diameter. This one would be about two thirds of that size.

Not bad really for a set that was likely in service over 20 years at the time of overhaul.

David
Attached Thumbnails
WS No. 52 Sender Cap C39A.JPG  
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  #304  
Old 27-04-20, 22:36
David Dunlop David Dunlop is offline
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Default

I was able to get the usual assortment of nylon, plastic and fine brass toothbrushes out today, along with a small electronics vacuum and an air gun set to 30 lbs., and get most of the dust and dirt cleaned from the chassis interior, followed by a careful wash and dry where needed.

Included in that process was the IPA 7 – 16 MC Flick Drive assembly from which the lower flick arm had become disconnected. The parts were in good shape and cleaned up well. The reassembly was straightforward and it is nice to see the parts back together again. I will refurbish the upper Indicator Flags on the three drives at a later date and try and get all that painting done and out of the way at once.

One thing to be aware of with this particular Flick Drive. It is not as secure in the chassis as the other two when freed from the front panel and has a tendency to wobble a bit if bumped.

David
Attached Thumbnails
WS No. 52 Sender 42.JPG  
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  #305  
Old 27-04-20, 23:11
David Dunlop David Dunlop is offline
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The two bottom sidepieces of the Sender chassis form the two rails it slides in and out of the Carriers No. 4 on, and they are held in place at the front of the chassis by the two lowermost panel screws. A pair of countersunk screws secures the back ends of these two rails.

Standing water a couple of inches in from the front of the rails had created a pair of noticeable rust blisters on these rails and I found these dug into the paint on the inner base of the Carriers enough to really make it hard to manoeuvre the Sender in and out of the Carriers as the rust blisters really dug into the paint.

The paint will eventually get stripped out of the interior of the Carriers, but in the meantime, I took advantage of the access to the bottom of the rails to buff the rust away and get a smooth metal surface back where it belonged.

One thing of note with these rails, as per the photos attached. They are heavy for their size and when the front set of retaining screws are removed, the rails have a tendency to swing towards each other. The one on the left about ¼-inch and the one on the right about 1/8-inch. Since these rails hold the thread for the panel screws, they need to be pulled into alignment when the panel goes back on. A small set of spring clamps should work nicely.

David
Attached Thumbnails
WS No. 52 Sender 43.JPG   WS No. 52 Sender 44.JPG  
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  #306  
Old 27-04-20, 23:42
David Dunlop David Dunlop is offline
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Default CANS, Metal, Shields Valve No. C1 ZA/CAN 4232

Two of the four 6V6G Valves in the Sender are shielded; V5B and V5C (the Driver Doubler and Driver respectively). They are visible right inside the Access Door with the two spring clip retainers secured against the tops of the two CANS with a wing nut.

The tops of both cans had accumulated water over the years, with V5C, closest to the front of the Sender being the worst. To get better cleaning access to the interior of the chassis, I pulled everything from the wing nut down to the CANS and decided to clean them up before reinstalling them. An interesting installation.

The wing nut was straight forward enough. The next down was a bit of a surprise; a small C-Clip. Popped it off and then the Spring Clamp for he CANS on V5C came off. Next a flat washer, followed by the Spring Clamp for CANS on V5B. At the bottom of the threaded post was the final flat washer.

It took a bit of cleaning but they now look aged, rather than totally neglected.

David
Attached Thumbnails
CANS, Metal, Shields 1.JPG   CANS, Metal, Shields 2.JPG  
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  #307  
Old 28-04-20, 17:09
David Dunlop David Dunlop is offline
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Default Changes in Composite Resistor Colour Codes

I almost forgot this little bit of electronics history.

Back in Post #303 about the sole upgraded/replaced component in this Sender, I neglected to mention the odd looking yellow component tucked in below the capacitor. It looked like a resistor to me but the markings were nothing I had ever seen before.

I took a photo of it and sent it to Jacques Fortin for identification. I received his reply last evening in which he confirmed it was indeed a composite resister with a pre-WW2 Colour Code. In the Sender, it is R46B in the PA Circuit for V7A, the 813 Power Amp. The resistor provides the keying bias.

Armed with that information, I went looking for its partner in the Sender, R46A, located in the V5D (6V6G) Screen circuit, where its job is to provide voltage dropping. When I found it, it sported the more conventional coloured ring code. Both resistors are original installations, with no signs of replacement on either.

The earlier code used a full body colour on the resister to identify the first rating digit. A wide band at one end was the second digit and the ‘Multiplier’ was a third band or blob in the middle of the resister. The Gold, or Silver, tolerance rating (if applicable) was applied at the opposite end from that for the second digit.

This older resistor coding pretty much disappeared in the 1940’s, but when I checked my Amateur Radio Handbook from the mid-1960’s, a detailed explanation of this older coding system for resistors was still provided. The information was completely gone from the handbook for my Amateur Course a few years ago.

Jacques also sent me the attached photo of some of these old resistors he has on hand. Colourful little suckers,

David
Attached Thumbnails
Vintage Resisror Colour Coding.JPG  
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  #308  
Old 02-05-20, 03:13
David Dunlop David Dunlop is offline
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I was able to cut two small pieces of 2x4 to block up the two Indicators today. This takes the load of their weight of the couplings to the Condensers and stops them from wobbling around.

All removable pieces are now off the Sender front panel as well, with the exception of the remains of the small phenolic resin mounting board for the TERMINALS, Aerial at the top of the panel. I need to carefully drill off the crimps holding the rivets for this board in place to remove the rivets, I need to size and source replacements to put a new assembly back in place when the time comes.

David
Attached Thumbnails
WS No. 52 Sender 45.JPG   WS No. 52 Sender 46.JPG  
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  #309  
Old 06-05-20, 17:27
David Dunlop David Dunlop is offline
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Default COUNTERS, 0/9999 2-3/4 inch x 1-3/8 inch x 1-7/8 inch, No. C1 ZA/CAN 4642

A little bit more chassis cleaning has been done. The current project was to get all the oily soot off the phenolic board directly behind the two COUNTERS, and the two COUNTERS themselves.

The board is now done and the left hand COUNTERS. I have about half of the right hand COUNTERS to complete. It nice to see that when the small windows on the two COUNTERS were cleaned, the numbers went from a dull yellow, back to their original bright white look. I was hoping, but not totally certain, that would happen. They look to be well-sealed units, but one never knows what time and hostile conditions can do to things.

I do find these COUNTERS are VERY jumpy, for lack of a better word. The slightest movement of the assembly starts the dials turning. It takes a bit of patience to get the right side assembly in its correct position for mounting to the front panel. At that point the dial comes nicely to all zeros. It is going to be a very careful reinstall when the time comes.

Because these COUNTERS are so sensitive to movements, I am thinking they must have been assembled and shipped from the manufacturer, with some sort of retaining clip, or block, fitted to prevent any dial movement until they were installed on the Sender, and said clip, or block, was only removed once the COUNTERS were properly in place.

David
Attached Thumbnails
COUNTERS, 0:9999  ZA:CAN 4642 13.JPG  
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  #310  
Old 08-05-20, 01:48
David Dunlop David Dunlop is offline
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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
Attached Thumbnails
WS No. 52 Sender 47.JPG  
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  #311  
Old 08-05-20, 02:33
David Dunlop David Dunlop is offline
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Default COUNTERS, 0/9999 2-3/4 inch x 1-3/8 inch x 1-7/8 inch, No. C1 ZA/CAN 4642

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
Attached Thumbnails
COUNTERS, 0:9999  ZA:CAN 4642 14.JPG  
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  #312  
Old 10-05-20, 20:38
David Dunlop David Dunlop is offline
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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
Attached Thumbnails
WS No. 52 Sender 48.JPG  

Last edited by David Dunlop; 11-05-20 at 15:03.
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  #313  
Old 11-05-20, 04:31
David Dunlop David Dunlop is offline
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I was able to pick up another piece for the Project today.

David
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3.8 Litre Mason Jar.JPG  
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  #314  
Old 18-05-20, 16:48
David Dunlop David Dunlop is offline
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Default TERMINALS, Aerial, No. C1 ZA/CAN 4716

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
Attached Thumbnails
TERMINALS, Aerial, No. C1 ZA:CAN 4716 j.JPG   TERMINALS, Aerial, No. C1 ZA:CAN 4716 k.JPG  
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  #315  
Old 21-05-20, 21:28
David Dunlop David Dunlop is offline
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Default AERIALS, Horizontal, 4-Section ZA/C 00087

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
Attached Thumbnails
AERIALS, Horizontal, 4-Section  ZA:C 00087 1.JPG   AERIALS, Horizontal, 4-Section  ZA:C 00087 2.JPG  
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