Wireless Set No. 52 Canadian - Project

[David Dunlop]

Hi Chris.

It would not be surprising to find a surge of none cork gaskets during and shortly after the war. Cork was a common supply in the greater Mediterranean area before the war but Portugal soon became the only supplier for the Allies and this likely forced exploration of other products. Cork trade probably remained limited until the last of the wartime rationing disappeared in the late 1940s or early 1950's.


David

[David Dunlop]

I was able to track down a 13/32-inch hole punch for leather work on the internet once I figured out how to describe what I was looking for more effectively.

McMaster-Carr carry them in many sizes for a good price and it was delivered in two days. This will make cutting the eight mounting holes in the cork gasket so much easier.


David

[David Dunlop]

The eight. perimeter. mounting holes in the cork gasket for the Aerial Base C2 Mounting Plate have now been punched out.

Next step will be cutting out the central 6-inch square to finish the gasket.


David

[David Dunlop]

There are several ways to make the final cut on the cork gasket for the Aerial Base C2 mounting plate and I have decided to use a cutting template for removing the central 6-inch square, since I have a pile of heavy card stock at my disposal.

I have now cut the 6-inch square template and the second photo today illustrates roughly how it will work. I will use some small pieces of double sided sticky tape to get the template correctly centred and then cut along its perimeter with a sharp blade to get the finished result.



David

[Chris Suslowicz]

I've fished out the British equivalent (it's a Monster) and noticed some string through the insulator mounting holes. Turning it over, there's a cork gasket there, to seal the joint between the aerial base (Insulator W/T H) and the Tufnol plate. There's then a cardboard (I assume grease or varnish impregnated) square laminated gasket with only 4 holes (at the corners) to seal the joint between the Tufnol and the vehicle roof.

You'll need a circular cork washer between the top half of the C2 insulator and your square plate to prevent water ingress, as well as the square gasket under the plate.

The British plate only had four bolt holes holding it on the vehicle because the base insulator flange is 8.5 inches in diameter, with 6 holes to bolt that down.

I need to photograph it (and all its related parts), if only to frighten people, but I'm still missing some of the 'F' rod adapters for use on the move.

The drawings in Wireless for the Warrior Volume 2 really don't do it justice.

Chris.

[David Dunlop]

Good to know all the extra bits are still with your mounting assembly, Chris.

The big cork gasket on the Aerial Base C2 mount is shown in the exploded diagram in the manual, complete with its CMC Part Number but does not show up anywhere else in any of the documentation. Maybe the assumption was it was a "set and forget" item that never needed replacing once installed.

I got the 6-inch centre cutout finished on mine this morning. All that is left on the Aerial Base C2 now is to strip the remains of the NATO Green from the upper and lower metal bits on the top section and redo them in SCC-2, or No. 2 Brown if one prefers. Finding a small rattle can of model SCC-2 would be a perfect amount. Must remember to check my Edmonton hobby store to see what they might have in stock.

The rubber flex section of my Aerial Base has a slight curve in it that I an hoping will slowly recover out of it. The poor thing spent about 10 years mounted on the back of a Dodge Command Car pretending to be a US Army Signal Corp aerial mount with the whip arced over the vehicle and lashed down somewhere at the front.


David

[David Dunlop]

I forgot to mention for Chris earlier that I do have the two Insulator Gaskets, CMC 114-069, alive and well and in full working order. Unlike the Mounting Plate Gasket I replicated, CMC 114-071, the Insulator Gaskets get a lot of mention in the manual.

The only bit I am missing at this point now is the Extension Assembly, CMC 114-083, which came in a cotton bag with its hardware. This was apparently only used when the Aerial Base C2 installation was on a vehicle with a very thick roof, or narrow aerial chimneys, to make hooking up the Connector Cable to the 52-Set easier. Those cotton bags were probably popular items for kids to lose their marbles in so not much chance of ever finding one and its original contents today.


David

[David Dunlop]

Searching for the correct sized brass flat washers to replace the missing ones on some of the Switchboard terminals has been an interesting exercise and I have had a lot of great help from a number of people here in Canada and the UK.

Finding 0BA brass hardware seemed a simple enough thing to do initially, until it came to the required flat washers. It is something not typically spec’d by a lot of suppliers, beyond the given BA size. What the Switchboard, Charging 5C Parts List stated was a 0BA nickel plated brass flat washer with an inside diameter of 11/16-inch, an outside diameter of 17/64-inch and a thickness of 3/64-inch. What you find today are a lot of Imperial, or Metric sized, flat washers being sold as 0BA, but not dimensionally correct.

Adding to the excitement was the discovery of several old specification charts for BA hardware that indicated there were two sizes of 0BA flat washers, a “Small” and a “Large”. Both had the same thickness and inside diameters, but the large one was the one with the 17/64-inch outer diameter, as used on the Switchboard, Charging 5C and 5C Mk I terminals.

Last weekend, Jacques Fortin contacted me to check out a supplier on Amazon, based out of China. The description of the item was very misleading at first, until I realized it was basically a string of ‘Hit Words” designed to grab the attention of pretty much any search engine combing the web for washers. Having got passed that hurdle, the required flat washers were found with correct dimensions and available in a package of 38 for less than $15.00 Cdn with free shipping. I ordered a package Sunday and they arrived Tuesday.

In the attached photos, these new brass ones seem a bit bigger, but that is just the colour differential at play between the brass new ones and the nickel played originals. I will be starting to plate these new ones later today.

I have also placed an order with BA Bolts in the UK for a 6-inch 0BA threaded brass stud to cut the two missing terminals from, and the necessary amount of standard thickness brass hex nuts and half thick ones.

Just one more brass hardware item to track down for the Switchboard now.



David

[David Dunlop]

Work on the Vibrator Supply section of the 52-Set Supply Unit is slowly moving forward.

I pulled it from the Supply Unit for some bench testing and while it was out of the Supply Unit, I decided to turn the set on to see what sort of reading I got from the meter on the Receiver, with regards to the 12 Volt LT input. This should be a straight pass through from the batteries, but with the Vibrator Supply in place, this value has always come up about 2 Volts DC too low. My CPP 2 Supply was providing 12.75 Volts DC to the Set. When I turned the Receiver on, the meter on the Receiver showed exactly 12.75 Volts DC coming in. Good to know, so I got curious and reinstalled the Vibrator Supply, and turned the set back on to see what happened. The meter was back down at 10.0 Volts input. What was different this time, however, was when I checked the HT Input to the Receiver on its meter, zero volts were coming in. Prior to this, it had always been 147 Volts DC from the expected 150 Volts. So onto the bench for a further look.

I am rusty with the electronics analysis these days, so I do a lot of triple checking and thinking, but have been able to determine the Vibrator and 0Z4A are both in good working order. The T7A transformer is providing correct input voltages to the plates on the 0Z4A to fire it up and I have continuity from the start to finish on the 150 Volt circuit. But one or more unhappy components exist in the circuit that will need ionvestigating in more detail.

This Vibrator Supply is a compact little sucker as noted in the two photos, so a very careful unbolting and moving of components will be needed to access suitable test points as the work progresses.


David

[David Dunlop]

The first pair of flat brass washers I prepped and plated this evening worked out very well. A nice even plating with a shine that matched the originals very well. So on I went to the second pair, doing everything just the same. Not so good this time.

The plating looked burnt black and was not at all complete. I did a little bit of research on line and the likely culprits are copper or zinc in the solution. I am leaning towards this because the 2 Amp trickle current at 12 Volts DC did not show up as a concern.

I was using solid copper wire for all of my electroplating and the first set of washers worked, so in theory, so should the second set. I will look for some steel wire to fabricate another Cathode fitting and try again on the weekend.


David