Wireless Set No. 52 Canadian - Project

[David Dunlop]

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

[David Dunlop]

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

[David Dunlop]

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

[David Dunlop]

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

[David Dunlop]

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

[David Dunlop]

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

[David Dunlop]

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