Wireless Set No. 52 Canadian - Project

[David Dunlop]

Hi James.

What colour is the Mouthpiece, Rubber No. 2 on your NOS Type 10 Headgear?

In the 52-Set Manual, the one photo of this headgear shows a white rubber mouthpiece. On the other hand, virtually all illustrations indicate the colour as black. The descriptions in all the 52-Set and 19-Set Parts Lists make no mention of colour at all.

My two NOS Type 10 Mouthpieces are both equipped with black rubber mouthpieces. I actually have a white rubber mouthpiece, but oddly enough it is fitted to a No. 7 Handset on an American made 19-Set Headgear Assembly and although still quite supple, it has developed a number of ring cracks just about the Bakelite lip on the mic cover it fits over. So I am not too keen to try removing it.

I am curious why white rubber was used for some of these mouthpieces unless somebody thought it might make the mic easier to find in the dark.


David

[James D Teel II]

David,

It’s black.

[David Dunlop]

I should have had my cataract surgery done BEFORE I started this project three years ago!

I say that as a preamble to I correction I must now make to a comment in Post #705, where I said my second set of Type 10 Headgear was a lighter coloured loom than the one I am restoring. Having dug it out this morning to examine, I find both headgear will be the same colour when completed and will match the two Drop Cords on the Main Set Supply Unit perfectly. Photos attached.

The plan is to use this complete headgear to map out all the connections correctly to make life easier when restoring the damaged headgear. Turns out it was a good thing I decided to do this.

Somewhere in its lifetime, a previous owner of this Type 10 Headgear made the same incorrect assumption about the headset straps on the Receivers as I had done back in the 1980’s when starting to learn about the Wireless Set No. 19 equipment.

At first glance, I had assumed the solid metal headset strap with the black padding went over the top of one’s head and the canvas strap wrapped around the back of your neck. I learned very quickly that by doing that, it is impossible to get the two receivers centred properly over ones ears. There is no vertical height adjustment available. A good friend sorted me out on that problem. I have now discovered somebody had the same wrong assumption and switched the bands around on this Type 10 Headgear. Once might be able to get away with that error with the Type 10 because in employs oval ear cushions rather than round ones so there is a slight height fudge factor present in them. Whoever designed the oval cushions, however, must have been aware of this problem in the field because the word ‘TOP’ is cast into one end of the oval. If all the parts of the headset are assembled correctly, the ‘TOP’ does indeed indicate the top of the entire headset assembly, not just the cushion and the harness leads end up at the bottom of the two receivers. Also, the left receiver lead ends up on the left side of the Grip & Clamp Assembly and the right receiver lead on the right side of the Grip & Clamp Assembly, with the larger Microphone lead in the middle.


David

[David Dunlop]

I now have two complete RCA Type 10 Headgear Sets that are once again fully working, to put towards the 52-Set Project.

It only took nine days, five sets of headgear and a pile of NOS parts to accomplish this, along with a very elevated amount of muttering. I am still unwinding from it all, but both sets are now correct for the 52-Set, from the RCA stamps on the 5-Pin Sockets and Microphone Cases up to the ‘Philco’ stamped receivers RCA used in their production.

I have the backstory behind this bit of work to sort out yet, along with supporting photographs and will post them up as soon as possible.


David

[David Dunlop]

I have not yet found any detailed wiring layouts for the Type 10 Headgear in any of the Wireless Set No. 52 documentation, other than the wiring setup for the two 5-Pin Drop Cords mounted on the Main Set Supply Unit. Fortunately, that bit of data matches similar information found in the 19=Set manuals.

So first step was to draw out the 5-Pin wiring in a larger format I could more easily reference while working on the headgear assemblies. The connections for the left and right receivers were readily visible and consistent across all headsets I had available, so I added that to this layout as well.

I knew there would be additional wiring to map out in the microphones once I got them opened up so I sketched out a diagram for the Phenolic Insert Holders & Plates Assembly ahead of time from several spares on hand, and filled it in when I got to opening up the microphone cases. I have added both of those drawings here at the start to get them out of the way.

From the Type 10 Headgear I have available, I suspect production evolved through an early and a late version related to two specific parts of the Headgear: the receivers and a Jumper Wire discovered inside the Microphone Case. Details of those will emerge in due course, but I will start with information next on what turned out to be the earlier version of the headgear.


David

[David Dunlop]

Leading up to this part of the 52-Set Project, I recently checked in with the 19-Set Group in England to get their opinion on the value of cleaning the contacts on the 5-Pin Connector Plugs and Sockets. The feedback was unanimously in favour of clean brass contacts, but to only get them that way with metal polishes, such as Brasso, or my favourite, Autosol. NEVER use files or abrasives as once too much metal is stripped away, the Connector is completely useless.

So my first step at this point was to polish the contacts on both Headgear harnesses I was going to restore: a pair with excellent original looms, 5-Pin Connector Plugs still sporting their RCA Stamps, and the Headset Receivers showing good yellow Philco Stamps and C-Broad Arrow Stamps. The Microphone Cases for both Headgear were NATO Green and there was a lot of dirt on everything and hopefully I had enough spares on hand to see me through any major surprises.

Once the Connector contacts were cleaned, I connected each Headgear in turn to an open Drop Cord on my 19-Set Mk III, warmed it up and checked to see what happened with the Type 10 Headgear.

Beyond the task at hand of restoring the two Type 10 Headgear, this little test revealed a somewhat larger issue that may prove challenging down the road.

The rubber on these Headgear Connectors, and the three Drop Cords on my 19-Set Mk III, have hardened dramatically. I could not get either Headset to fully engage with the Drop Cord. The brass ring just disappeared into its mating connector and that was it. A good quarter inch or so short of fully engaged. Discretion screamed at m not to get picky at that point. The connection established worked and it was still possible to disengage the Connector. I also made a note to myself to NEVER try disconnecting the headset on the 19-Set Mk III. It was last connected back in 1982 and is probably set in place now. I will have to think the hook-up of headgear to the 52-Set very carefully when the time comes.

The first Type 10 Headgear I tested proved interesting. With the 19-Set warmed up and idling, as soon as I tried joining the headset connectors together, Pin-1 on both sides (the Pressel Relay) threw the Set into TRANSMIT Mode and fired up the Dynamotor. Not a good start. So back to the workbench to disassemble the Microphone Case and map out what was going on inside.


David

[David Dunlop]

I will start off this Post with a wee apology for the readers.

In spite of the best-laid plans and intensions, the actual physical work put into restoring the two Type 10 Headgear had no real linear flow two it once underway. I ended up having to frequently hop back and forth between the two headgear and sometimes off in completely different directions in order to sort everything out. It is taking longer than I hoped to pull all that work into a logical, understandable flow to document it all effectively. I have had to take a few more photos of things I missed originally, or take better photos and then sort them all and tie them together with hopefully sensible notes. So please bear with me.

The first two photos here show the actual Microphones Case (ZA/CAN 1557) and Covers (ZA/CAN 1564) along with the Rubber Gasket (ZA/CAN 1565) stuck to the Cover. Loose fitting Gaskets were found in most of the Microphone Assemblies I was working with, but one did show signs of being varnished in place on the Case side. Surprisingly, all of these Gaskets were still very supple. The Cover is secured by four Screws, ANC, Brass, RH, 4-40 x ½-inch and internal toothed lock washers. Once they are removed, you may be able to pull the Cover off the case, but usually I needed to gently inset the blade of a Putty Knife into the seam between the two parts and gently twist them apart. If you are careful, the gasket will simply squeeze out of the way and be just fine.

These photos also show the Buttons, Phenolic, Pressel (ZA/CAN 1556) and Springs, Steel (ZA/CAN 1569) mounted to the outer upper top of the Case by Plates Assembly (ZA/CAN 1568) on the inside. Total movement of this Button is only about1/8-inch, which closes the two Contact Spring sets nicely, assuming they are still perfectly straight and vertical.

About halfway down either inside face of the Case, you can see a set of vertical ridges cast into the aluminum. These engage slots on the outside of the Holders, Phenolic, Insert to keep it, and the Microphone Insert it holds, correctly oriented inside the Case.

The third photo shows the microphone cord Rubber Grommet and Washer factory fitted. The Washer is, in fact, the Anti-Strain for the microphone cord. The large metal crimp securing the loom at the top of the microphone cord has two small rectangular tabs 180 degrees apart, bent up from the cord 90 degrees at the top end of the crimp. The Washer and Grommet slide up against these two tabs. When the rubber grommet is slid down onto its groove on the Case, the Washer slides down the inner face of the Case and is held between the two cast columns for the Cover Mounting Screws. In doing so, it clamps the Grommet is place, making it easy to fit the Cover onto the Grommet when the Cover is reinstalled. If the Grommet has perished and fallen away as many have, the inside half will still be there protecting the cord. The only way to install a new Grommet is to split it open with a sharp razor blade or scalpel and slip the Grommet over the cord. I had to do that one of the Type 10 Headgear I restored. I thought I would explain how it all works here. Oddly, however, I can find no part number or description references at all for either this Grommet or Washer in either the 52-Set or 19-Set documents I have on hand.

The last photo in this Post shows the conditions inside the Microphone Case of what appears to be the earlier version of the Type 10 Headgear, when I first opened it up. A lot of rust dust evident and other signs of high moisture. Interestingly, the Pressel Button still functioned nicely.

Of particular note at this point, are the squares of black rubber coating the upper back portions of the two Contact Spring Assemblies. The other oddity upon opening this Microphone Case up was that the Microphone Insert was well and truly stuck in its Holder Assembly. It should have been a secure fit, but easily pulled free with ones fingers.

As you can see, the wiring is nicely tucked around the perimeter of the Holders for the Microphone Insert. In fact, the lengths of each wire to work with are very consistent with where they have to go for connection. The tracers on four of the five wires match the documentation for the 5-Pin Connector Plug. The one deviation is that a double back tracer has been substituted for the Green Tracer in the manual diagrams. At first glace, it all looks pretty normal, doesn’t it!


David