Wireless Set No. 52 Canadian - Project

[David Dunlop]

As I have mentioned before, working with the surviving documentation for the Wireless Set No. 52 is a real challenge for a whole host of reasons, but it is what it is. You just have to read through every document you have, frequently several times, to locate all the information available for any given topic, and then make the best sense of it you can.

A good example recently surfaced regarding the Brushes in the two Dynamotors. Most of the available information regarding the inspection and maintenance of these items states the eight brushes should be inspected monthly for damage and wear. They should be carefully removed from their holders, checked and put back exactly as they came out. New ones must be worked in with an hours run time under no load. None of the information I had found to date advised how to access all the Brush Holders in situ, and the removal of the actual Dynamotors from the Supply Unit for servicing covered only the upper one (MG1A).

Not sure how I missed it up until now, but I was looking through the Working Instructions last evening and discovered a little table tucked away near the back of it explaining how to inspect each of the eight brushes when the Supply Unit is out of the Carriers No. 4, which was a very nice find. It also mentioned it is not necessary to completely remove the brushes from their holders to inspect them.

I posted the page here for future reference.


David

[David Dunlop]

Slow and steady still with this project, focusing primarily on ensuring the Supply Unit is in good order before going back to the Sender.

I have now confirmed the oddball reading of just over 70 Ohms I got on one of the Supply Unit Resistance tests relates to a pair of 300 Ohm 1/2-Watt resistors set up in two parallel feeds in the Vibrator circuit for the Receiver Supply. This parallel arrangement of the two 300 Ohm resistors should produce a resistance value of exactly one half the rated value of either resistor, or 150 Ohms. So one, or both, of those two resistors has dropped significantly off specifications. Confirming test yet to be done.

I spent a chunk of yesterday afternoon searching the web for a supply of 300 Ohm, 1/2-Watt Carbon Composite resistors, which proved a bit of a challenge. Current standards now bracket that Ohms value by about 20 Ohms either side. I did, however, eventually find a supplier with 300 Ohm 1-Watt carbon composites which will work nicely, so will be ordering 10 for the project. That will give me a chance to match a pair for this fix and leave me spares for the rest of the project, if needed. The two in the Supply Unit are R13D and E, so at least three others are in the 52-Set in other locations.

When I had reinstalled the Supply Unit in the Carriers No. 4 to allow for the Isolation Relay to be tested in the Sender, I had the meter set up to monitor the Sender data. Last evening, I fired up the Receiver to see how the signal from WWV at 10.0 MC was behaving, so I had switched the meter back to monitor the Receiver. I was very surprised, and pleased, to see the LT was reading a rock steady 11.25 Volts DC and the HT a rock steady 155 Volts DC. Checked again this morning and same results. They are no longer wandering all over the dial, as low as 10 Volts LT and 120 Volts HT. What I find odd is I have yet to do any electronic adjustments or repairs to the Supply Unit that may have caused this to happen. I still intend to more closely examine the Connector assembly between all five 8-Pin Connectors across the set, but another related possibility is oxide buildup on all those contacts, so I shall add cleaning all the related sockets and plugs with Deoxit just to be sure.

I have also noted that when the time comes for hot testing the Sender, it needs to be done at High Power. I am glad I picked up the extra CPP-2 Power Supply from Brian Asbury last year. It is soon to come in real handy.

David

[David Dunlop]

One other small note.

We are getting used to being able to reach the full Internet once again with our new 24-inch iMac. We still have to get an external storage drive to transfer all the photos and documents from the old iMac onto, which will probably take a while behind the scenes. We were reasonably diligent enough to ID nearly all of our photos and set up a filing system, but failed to keep transferring new photos to the files consistently. It will be a time consuming pain to get it all sorted, but we will, this time. It makes life so much easier when done and adhered to.

I have also now been looking at Vector Graphics software as a potential solution for the water transfer decal project down the road. What appeals to me about it at this point is that it can remove the print dots and pixels from digitized printed images and thereby allow the images to be enlarged without the image breaking down. That would be a huge help as few, if any, Supply Units or Coils, Aerial Tuning seem to have survived with factory original decals still in place, so the panel photos from the Operators Manual are the only viable option.

David

[David Dunlop]

With the realization a couple of weeks ago that the next major step in restoring the Sender is going to be completion of the remaining tests, it also dawned on me a number of those tests require the set to be actively running in HIGH Power Mode. Initially I was thinking it was great I had purchased a second CPP-2 Power Supply from Brian Asbury a couple of years ago, as that gave me the ability to have enough amperage with the two running in parallel mode, to avoid any problems operating the 52-Set. Then last week, I realized I did not have a second set of output cables to hook up the second CPP-2 to my 12-Volt Distribution System. So I quickly emailed Brian to see if he still had any of these in stock. They were initially C42 Set items. He advised me he did not, but that he did have a Chorehorse connector that might work for me, and sent me a photo of it.

This cable arrived in the mail this morning. It is NOS, still with the factory original cotton twine holding it all together. See the first photo. When I finally saw this cable up close, it jogged my memory and off I went to search the Illustrated Parts List for the Wireless Set No. 52. What I found is the illustration in the second photo: Connectors, Twin, 5-ft, No. C1 ZA/CAN 4732.

Brian’s reference for this cable is: Connector, Twin, 6-ft ¾-inch, No. C1 ZA/CAN 9682.

I have found it is always a bit of a challenge trying to figure out how the measurements of many wireless cables are derived. When I put a sewing tape to this one, the loomed centre section is 55 inches long. From the end of the loom to the two lugs is another 5 inches. From the loom to the two clips is a further 15 inches. So both the 52-Set references and Brian’s could apply to this connector.

The ZA/CAN 4732 reference for the battery cable used with the ZE-12 Remote Supply in 1944 probably was used with the ZE-11 Remote Supply for the Wireless Set No. 9 Mk I that predates the 52-Set. My three wartime Chorehorse manuals and all my 19-Set and 52-Set Ground Installation manuals mention CONNECTORS, Twin, No. 53 ZA 2794 as the sole item used to hook up the 6 –Volt DC Chorehorse of the day to the Switchboards. This cable is listed as a 30-foot rubber covered item and its ZA-Number is very low.
So the mystery is whether or not ZA/CAN 4732 and ZA/CAN 9682 are one and the same cable? The latter ZA-Number suggests a post-war item; perhaps from the time 24-Volt Wireless Equipment was becoming common. Chorehorses by that time were largely 12-Volt Units. So maybe the wartime 52-Set cable was reintroduced with a new ZA-Number, based on the change in voltages in Chorehorses from 6 to 12 Volts.

In any event, I am thrilled to have this cable now, as it will truly be multifunctional with this project.


David

[David Dunlop]

While taking another look at the new Connector Cable this morning, I noticed a rubber grommet at the end of the loom on the lug side of the cable. This grommet does not exist on the wartime Connectors, Twin, 5-ft, No. C1 used with the Remote Supply. The battery terminals on this supply are located on the lower chassis, outside of the area enclosed by the Cover Assembly of the supply.

So maybe this later version of the Connector Cable had to pass through a cover/door/panel on whatever piece of equipment it was intended for, in order to reach the terminals it had to be hooked upon. Maybe it was the addition of this rubber grommet that prompted issuing a new ZA Number?


David

[Chris Suslowicz]

As I understand it, the length given is that of the wire/cable only - and the length you cut off the reel to make up the assembly.

The WS19 connectors started out as an immense range of 12-12 and 6-6 leads, with the connector faces in the correct orientation (crimped and soldered in place) for the application.

The next version (with bakelite connector inserts and repositionable connector shells (remove spring clip and rear cover, rotate front of connector to desired position, replace rear cover (which locked it in position) and spring clip) made things a lot simpler, reducing the range needing to be carried) was repairable, could be modified by the installer, and reduced the range to (approx.) 16 distinct variants (Connector, 12pt, No.50A - 50P)

Post-WW2 they were referred to by the cable length, so you didn't need a manual to find out which suffix letter was required for a particular job.

This also works for wire and rod aerials: the Aerial 100-ft No.5 is made from 100 feet of Wire, Electric, R3, and that includes the loops and straps around the insulators, so the aerial never has a physical length of 100-ft (unless someone screwed up while making it up - I have a Canadian 4-section aerial that is unusable because the first section is 10-ft too long!)

Sectional rod aerials are the same: the 14-ft folding rod for WS62 is made from 7 sections each 24-in long, and there is no allowance made for the 1-in or so lost in the joints.

Best regards,
Chris.

[David Dunlop]

Thanks for the input on wire lengths, Chis. Much appreciated.

My apologies if rumours of the death of either myself, or this project, had begun to circulate. Neither is true.

I have been sidetracked during the three sets of resistance tests I needed to complete on the 52-Set Sender. The main cause was some very odd readings I was getting. The initial assumption was a serious fault, or faults, lurking somewhere in the Sender, but as I pondered all the data; a more likely suspect for the high readings began to be my Digital Multimeter. It has performed very well whenever I needed to test a more modern, solid-state piece of electronics and never gave its reliability much thought. I began to have second thoughts when so many Sender tests started showing up where the DMM sampling rate simply would not stabilize, and would start a massive sweeping action, either in Full Auto Resistance Mode, or a narrower manual resistance range. In Auto, it invariably ended up reading at Infinity and stop working.

15 or so odd results showed up in the final data collection and I was suspicious enough to pull out my RCA VoltOhmyst VTVM (actually the recommended VTVM in the Canadian Army Test Instructions for the Wireless Set No. 19 and the 52-Set) and randomly sampled three of the odd tests. All three came back higher than I would have liked, but not even close to the ‘Infinity’ values the DMM was giving me.

So I started redoing the testing with the RCA Analog Meter for all the really odd values and from time to time rechecked a few of the tests that came back OK on the DMM. All was going well for a while and then the good test results started going off. A quick check of a couple of known resistance standards showed those results were now out and panic set in. After about a week, it dawned on me I had been watching the RCA Analog Meter warm up and was checking the Zero status of the needle in voltage mode while the meter warmed up, but had forgotten to also Zero the needle for Ohms. So I tried that and could not get it to Zero to save my Soul. I had put a brand new pair of D-Cells in the VTVM in January, so they were not on my radar, but should have been. When I finally realized they were worth a look, one tested 1.34 Volts and the other came in at 0.32 Volts. Popped a brand new set in and problem solved.

In the meantime, checking my two digital multimeters showed both were quite accurate and the RCA gave me results that were so close to correct resistance values I was a happy camper. However, my only backup analog multimeter, a cheap modern one about 15 years old, was consistently 25% off values for resistance, It’s manual claimed +/= 5% when new. So I was short a reliable analog backup.

I have now found a very nice, very accurate Simpson Model 303 VTVM, and being a give away, I am a happy camper and can now get these tests finished on the Sender.

David