Wireless Set No. 52 Canadian - Project

[David Dunlop]

Yes, Bruce, I am quite pleased at how things have been progressing and I do hope the ethers tidy up over the Winter season enough to improve the listening experience.

I have been able to confirm that the R58A resistor in my Remote Receiver has packed it in. It is a pair of 1.2M Ohm resistors actually. The Master Parts List provides two options of a single 600K Ohm or the aforementioned pair, but of the three receivers I have for inspection, all are equipped with the paired arrangement. I wonder if the single resistor configuration was very early production, or very late?

In any event, both of this particular pair are fully open and toast. I have tracked down a supply of carbon composite resistors that match the factory originals and once on hand will swap the offending pair out. Took a while to track down the location of the R58A on the chassis but did finally find them, with the help of a nice bright LED torch, sitting on the long terminal board on the underside of the chassis. See the attached photograph. They are the pair immediately right of the empty pair of terminals on the right half of the board.

I think I may take some time to ID all the other components on this board for future reference. Particularly the resistors. In poor lighting, the background colour and the aging of colours can make it a bit of a challenge to spot the typical resistor colour codes easily.

David

[Chris Suslowicz]

Originally Posted by David Dunlop

Yes, Bruce, I am quite pleased at how things have been progressing and I do hope the ethers tidy up over the Winter season enough to improve the listening experience.

I have been able to confirm that the R58A resistor in my Remote Receiver has packed it in. It is a pair of 1.2M Ohm resistors actually. The Master Parts List provides two options of a single 600K Ohm or the aforementioned pair, but of the three receivers I have for inspection, all are equipped with the paired arrangement. I wonder if the single resistor configuration was very early production, or very late?

600k is not one of the 'preferred values' in general use, so while it might have been the designer choice in practice it would have been a pair of 1.2M resistors (which are in the E12 preferred value range). The closest single E12 value otherwise is either 560k or 680k (all values +/- 10%. A pair of E12 resistors meant one less specialised stores item (that may just have been used in that receiver) that needed to be carried by workshops.

Chris.

[David Dunlop]

That would explain it, Chris. Thanks.

I did actually find one supplier in the States with NOS 600K Ohm carbon composite resistors correctly rated for this receiver, but passed on them because they seemed an odd/rare value and I wanted to maintain the original configuration of the Remote Receiver. Interestingly, this same supplier also has a stock of NOS in the box Delco Dynamotors for the 19-Set. Amazing what turns up when you don’t need it.

David

[Bruce MacMillan]

Actually 600k was a standard value of resistance. The E series of resistance is the EIA values that weren't adopted until 1952. Prior to that resistors had values like 400k, 500k, 600k,etc. Have a look at an early Allied or other distributor catalogue. Same applied to early capacitors. Old values of 0.02 & 0.05 became 0.022 & 0.047, etc.

[David Dunlop]

An interesting bit of Electronic History, Bruce. Thanks for the post.

Funny how we can sometimes grow up surrounded by a given set of standards and take them for granted as always having been there. Just checked my 3 year old Basic Amateur’s Course text and no mention of said standards transition for resistors or capacitors. Tubes/Valves are still given a mention, however.

Life is indeed a never ending learning curve!

David

[David Dunlop]

A supply of vintage NOS Carbon Composition Resisters arrived today. The 1.2M Ohm ones needed to replace the dead pair in my Remote Receiver HT Meter Circuit. Shipped up within a week from Radio Daze.

Hopefully, once the dead pair of resisters is replaced, that final meter circuit will spring back to life and I will be that much further ahead in this phase of the project.

I was also able to spend some more time detail cleaning bits of the receiver, in particular, the tuning dial Lots of nicotine came off the parts and a bit of surface rust around the dial rim. That work seems to have removed the small radius of sticking I was experiencing when rotating the dial. I did, however discover the course control knob of the slow motion drive has a wobble to it. Odd because it does not feel loose at all. It just rotates like a bent rim on a car. I will take a closer look shortly. If it is a bent control shaft assembly, I happen to have a spare in my 19-Set Bits Box, so can swap it out if the need arises.

Once the meter is back to full functionality, it will be the valves that will get a closer inspection, which means a small hiatus from the 52-Set Project while I build a British Valve Adapter for my tube tester.

David

[David Dunlop]

I recently ran across a small stash of boxed, NOS Canadian Marconi valves for the Wireless Set No. 52 and at a price of $5.00 each (Cdn) could not walk away empty handed. When received, they turned out to be 5 ARP-3's and 1 12Y4.

Over 70 years of sitting, the cardboard packaging has suffered somewhat from moisture. I discovered this by reading the outer red sleeves, which are generic in design it turns out. They state that the relevant patent information can be found inside, but I could not see/find any such paperwork at all in the ARP-3 boxes.

When I finally got to the 12Y4, I discovered the outer sleeve was indeed a sleeve. The valve slide neatly out of it, contained in an inner retainer. The outside of this retainer had the patent information printed on one side stating that the valves were "Licenced under Patents owned and/or controlled by Thermonics Limited." Patented 1925-1943 inclusive." I can find nothing at all on line now about Thermonics Limited so assume it has long since vanished from the business scene.

On the side directly opposite on the inner retainer from the Patent information was the warranty information that referred the customer to a number of Radiotron offices across Canada for exchange/service. Interestingly, they had an office in Winnipeg at 356 Main Street. That was on the West side of Main Street, midway between Graham Avenue and Portage Avenue. That entire block was levelled in the 1970's and a major office tower complex constructed. At the time the Radiotron office existed, however, it would have been right next door to the CN/CP Telecommunications Centre in Winnipeg, the local hub of Telegraph activity in Manitoba.

These inner retainers are generic in design as well, capable of holding any capped or uncapped valve of the appropriate size. a white strip on the cap end of the retainer bears a black stamped ID for the valve inside.

I am guessing that Radiotron was a valve manufacturing division of the Canadian Marconi Company. Three of the ARP-3 valves are stamped with a manufacturing date of "10'41". The other two were 1943 dates I cannot recall and did not write down. When cleaning the valves in the Remote Receiver, I noted a number were dated "9/43" and some 1944 dates showed up as well. Note to self to document that data.

No sign at all of any dating on the 12Y4's so far.

David