Wireless Set No. 52 Canadian - Project

[David Dunlop]

The Sender is now laid out for disassembly and cleaning. I have the back of it resting on two 18 inch sections of 2 x 4 lumber to protect the pair of 8-pin connector sockets on the top rear of the chassis. This keeps them well off the surface of the work desk.

I wish the rest of the chassis interior was as clean as the bottom section. Sigh!


David

[David Dunlop]

I spotted one of these BA Tap and Die Sets on Amazon Canada a couple of weeks back and ordered one. It arrived this afternoon.

It will very likely get put to good use cleaning up threads on various parts of this 52-Set project.

David

[David Dunlop]

There are a couple of rivets used on the 52-Set I need a correct identification for as some of the project work down the road is to replace a couple of parts fastened by them. I think they are either called tube, or hollow rivets and appear to be plated brass in nature.

The first type are illustrated in the first photo of Post #248 and here. They have a shallow truss head and are used to hold the AE Aerial Terminal in place on the Sender.

The second type is a full countersunk head rivet used to mount the fixed receptacles for the cowl head fasteners. the 2nd and 3rd photos are of this style rivet.

David

[David Dunlop]

I will be pleasantly surprised, if I ever chance to run across one of these original Leads in complete, working condition, so I have moved on to the alternative idea of reproducing it, as best I can with available modern components.

The first step in this sub-project came about back in February of this year (Post #240) when I found the suitable single conductor cable. This sub-project also makes for a nice break from the rather tedious task of cleaning the front panel of the Sender, a task that is a tad hard on my pinkies these days.

The original end terminals for this lead assembly were a one-piece sleeve version of a Motorola Pin Connector. The central copper conductor fed through the pin and was soldered in place at the tip, essentially making the sleeve ‘hot’ during transmission. An extensive search of the Internet showed a lot of modern Motorola Pin Connectors available, catering to the various sized coax cables on the market. A number could be found with the required 7 mm inside diameter, but the outside diameters were all far too large to clear the guide holes and eyebolts across the upper front of the main 52-Set. I then started to think of the possibility of building the necessary Motorola Pin Connectors from suitable parts, if such could be found.

I started by searching for 7 mm inside diameter metal sleeves, which opened a staggering number of possibilities. While plodding through some online photos of possible metal sleeves one evening, I spotted a small, brass, ‘cord tip’ which was ¾-inch long (the required length) but basically shoelace sized. It came from a company identified as “ozbrassshop.com”, which I assumed was in Australia, so I headed to their site to have a closer look at their product line. Yikes! They listed over 10,000 items, nearly all in brass, catering to the craft and jewellery making market, and they were based in Istanbul, Turkey. Well, I had gone this far!

Yes, I spent the better part of two entire evenings going through the entire product listings for the ‘ozbrassshop’. 48 images at a time. It paid off.

Near the end of their listings (of course it was) I found what I was looking for: Item # ENC7 2402. It was a package of 20 pieces for $8.00 USF and free shipping, and the item was:

End Cap, brass 8 x 20 mm (7 mm inner) raw brass (4.5 mm top hole) cord tip ends, ribbon end.

I ordered them.

The attached three photos show the tip on its own, fitted over the 7mm cable and how nicely the tipped end will pass through the two eyebolts on the top of the Sender panel. The one fly in the ointment at this point: the eyebolt on the top of the Workshop 202 rebuilt Supply Unit has too small an inside diameter. Something else has now been added to the ‘To Do List” for this 52-Set Project.

More to come on this Leads, Aerial 25-3/4 inch Project shortly.

David

[David Dunlop]

The third piece of the puzzle for fabricating a suitable Leads, Aerial 25-3/4 Inch was to be able to source a suitable central pin assembly for the tips. This is where the modern Motorola Pin Connectors come into play. The vast majority of these have a ½-inch pin fitted (the necessary length), but not all. Most venders on line do not provide much information regarding the pins on the products they offer, so you have to email them and ask. The more critical issue regarding the pins today is the construction of them. It is not always evident from the photos provided. Three methods of manufacture are used for making the pin components.

The cheapest method, and the most likely one to produce garbage, is an attempt at rolling a small rectangular strip of metal which results in a series of three and a bit longitudinal folds for the length of the pin, and the two longitudinal edges end up overlapping one another to some random degree. The finished pin should have a .125-inch diameter. The problem with these pins is the sides of the folds are rarely equal; so one measurement across the pin will be in excess of .125 inches, causing the pin to jamb in whatever it is plugged into. I would avoid this type of product at all costs.

The second means of pin making, uses equipment that produces a true rolled pin body cylinder, with the two longitudinal edges butting up smoothly and evenly against one another. The cylinders are then cut to the required length and the rounded tip and flared base formed. They cost more than the first type, but are more commonly found and the diameters consistently measure very close to spot on .125 inch.

The last type of pin production involves extruding the pin metal to produce a long closed tube. Pieces are then cut to length and formed as per the second option above. Specs are very high tolerance and the products these pins are fitted to are the most expensive. Just remember to always ask for the specifications of the pin before buying.

The first photo attached shows the off the shelf Motorola Pin Connector I purchased from an eBay Store called ‘Antenna World Inc.’, based in Miami, Florida. The Seller goes by the name ‘platech1’ and the Item Number was 361514744308. The item is described on the site as follows:

10 Lot Motorola Male Car radio antenna connector Crimp Solder RG-58 RG-59 RG-62

The second photo shows how the crimping end of the outer sleeve can be bent to the side and the sleeve spread open to release the inner plastic insulator assembly holding the pin. A very pleasant surprise at this point was to find the diameter of the pin base is just one half mm smaller than the end hole of the brass sleeves I purchased. Also, in these first two photos you can see the longitudinal seam down the side of the pin. This should allow good solder penetration from the tip and side of the pin and also allow the base of the pin to be soldered effectively to the end of the sleeve when the time comes. So the sleeves will be “hot” on these fittings, just like the originals.

The outside diameter of the plastic insulator is at a maximum of 7.5 mm, so the insulator needs to be thinned down to the point where it is a snug 7 mm. I want to avoid any wobble in the final product if at all possible. Lacking a lathe, but having a drill press, the drill press gets the job assignment. I found a 13/64-inch drill bit shank is a snug fit when inserted into the cable end of the insulator. It would probably not be snug enough to resist slipping when any load was applied to the outer surface for long, when the drill was powered up. The solution was to place two layers of saran wrap between the drill bit shank and insulator when inserting the drill bit shank. Very snug now…yet removable in the end. The plan is to use thin strips of fine, to very fine, sand paper against the side of the spinning insulator to slowly trim it down to the needed diameter.

The third and last photos show the fitting of the Saran Wrap, before and after trimming away the excess.

Will let you know how that turns out.

David

[Chris Suslowicz]

Ah....

What diameter is the central pin on the original?

I'm asking this because I bought a post-WW2 test kit last Saturday "Aerials, Dummy, No.2 and No.3" and this contains a bunch of short connecting leads with plugs that approximate aerial rods, the standard wrap-around spade lugs for the spring-loaded terminals on the WS12 and R107 (etc.), and the other end is a turned pin, probably nickel plated, that fits a slotted terminal as used on field telephones.

The pins are smaller diameter than the insulation on P11 cable (which they are fitted to) and the junction covered by a rubber sleeve.

I wonder if these were a standard WW2 item?

Chris. (G8KGS)

[David Dunlop]

Hi Chris.

Good question on the original pin diameter size. That little detail is missing from the Master Parts Listings. They do, however, identify that the slot in the AE Terminals into which the pins fit, are 1/8-inch deep and I found a 1/8-inch drill bit shank slides in and out quite easily.

The other factor that I ran across is that the 1/8-inch pin size seems to have been a standard for many decades for the Motorola Connectors used with automobile radio aerial leads. At one time I think the sockets used to have spring loaded innards that gripped the aerial connector sleeve to hold it in place, but todays versions appear to have switched that up. The spring grips are now on the connector sleeve, or they use a bayonet type lock.

Years back, a smaller version of these pin connectors were common for speaker and headphone connections to wireless equipment, so that might be another possibility for you Chris.

David