Wireless Set No. 52 Canadian - Project

[David Dunlop]

And the Matt black version.

David

[David Dunlop]

It could prove to be an interesting four days coming up.

I was giving the 52-Set a routine workup two nights ago, running the receiver for about 20 minutes with the Sender Heaters active. Then switched on the Netting to run the 300 Volt Dyno for 3 or four minutes. I then switch Netting off and switch the set from Reeceive to Send. This turns the 300 Volt Dyno back on with the 1200 Volt Dyno. I normally let this pairing run a couple of minutes and power fully off. Done this several times a week for nearly three months.

This time...not 5 seconds from switching to Send, I could smell burnt varnish/wax coming from the Sender Blower Door so switched off immediately. So this weekend the Sender comes out of the Carriers No. 4 again for a close inspection.

David

[David Dunlop]

With an even mix of curiosity and trepidation, I decided on a simple test of the 52-Set this evening.

I warmed up the Receiver and Sender Heater circuits for nine minutes, took a deep breath and switched on the Netting circuit for the Sender. This activates only the MG1A (300 Volt Dynamotor).

A constant sniffing of the air at the Sender Blower Door showed no sign of a smoke smell and a nice subtle ozone smell from the Supply Unit Blower was evident. After two minutes running, all was still well.

This at least tells me the problem is somewhere in the 1200 Volt circuits of the Sender.

Every little bit of information helps.

David

[David Dunlop]

I pulled the Sender out of the Carriers No. 4 this afternoon and got it on the bench. 20 minutes later, after a careful visual examination, I could see, or smell, no trace anywhere of recent overheating.

Next step will be removal of all the valves and a complete redo of the three resistance tests for the Sender using the same VTVM I did the original tests with earlier this year. This was something I had planned to do anyway after carefully cycling the 300 and 1200 Volt power feeds from the Supply Unit though the Sender over a period of time.

There were a cluster of unusually high resistance readings in the first tests I am curious to see any possible changes in. Also, I may now find an earlier, normal resistance value that has suddenly gone south, which might point to the potential new problem. It will take a few days to complete, since access to a few of the test points required temporary unfastening and moving of some components.

David

[David Dunlop]

A rather nice parcel arrived in the mail today from Alberta.

This particular Curtain, Waterproof is a replica, made over 20 years ago by an Edmonton tentmaker, copied from a borrowed, surviving original at that time. They could not get a perfect match to the original colour of green canvas from available stocks and the weight is slightly lighter than the original as well. What I liked, however, is they matched to the nickel plated hardware on the original.

I do not know where the original Curtain, Waterproof came from, or ever ended up, but at least we know it was still surviving a while ago.

While installing it to warm up and hang, I discovered the rightmost Lift The Dot post riveted to the top of my Carriers No. 4 has been bend slightly to the right. Surprisingly, the post itself seems to be OK. The bend had taken place in the upper sheet steel of the Carriers No. 4. With a little TLC down the road, I might be able to dolly the sheet metal back level. Added to the ‘To Do’ List in any event.


David

[David Dunlop]

Thought I had better show a photo of the Curtain, Waterproof rolled up in the stored position on top of the Carriers No. 4, while I have the Sender out for testing. Notice how it forms a smooth, cylindrical tube when fastened down.

Anyone with an original Curtain, Waterproof can probably confirm this, but the smooth look of this curtain in the stowed position is very likely due to the fact it is a replica made from a bolt of canvas that has not been treated with the usual paraffin and wax solution to actually waterproof it. You will notice in the first photo of my previous post, when in the deployed position, the weight of the steel bar in the bottom edge also holds the canvas in a smooth tight sheet.

I noticed these effects last evening and checked the waterproof covers on my Mk II 19-Set and Variometer and my Mk III mounted on the Carriers No. 23. All three of these canvas items are very stiff, you can still smell the waterproofing when they get warm and they only ever really 'relax' when they get warm.

I don't think I will ever bother to apply any traditional waterproofing to this replica, but I might give it a spray of silica boot waterproofing, just to validate the name of the curtain, if nothing else.


David

[David Dunlop]

The 3rd set of resistance tests for the Sender were completed yesterday and overall, the results were very consistent with the two sets of tests run last Spring.

Of none electrical note, the rust on my VTVM Testing Procedures is now shedding in huge chunks. Most of the red flag readings I took earlier that were ‘Infinity’ in nature produced excessively high, but real values this time around. This was primarily due to me focusing on taking advantage of the different testing ranges on the meter to see if and where I might actually get a useful reading. It is amazing what one can forget when being an infrequent user of helpful equipment.

The majority of the good readings were either identical to the earlier ones, or +/- very, very close, so that was nice to see as well. The red flags are all clustered in the same circuits as earlier and the other big plus was nothing new showed up that might have been related to the overheating event that happened a few weeks back, so I have inflicted no new damage…so far.

The dark side of all this, however, is my next step in the process. I now have to go back to the Sender Circuit Diagram and methodically trace out each red flag circuit to identify all the related components. There are likely a few resistors that have dropped off in value, but most of the problems are probably going to be with the PIO Capacitors that have transformed themselves into resistors. The problem now though is the 52-Set Circuit Diagram for the Sender is very compact for easy reading/tracing. One sooner or later has to resort to using a magnifying glass, or lamp, which narrows down your field of view, compounding the problem. A whole different experience from working with 19-Set diagrams.

The challenges don’t stop there either. Once I have identified all the components that need further investigation, I have to find them on the chassis and test each. The ones tied to valve socket terminals are the easy ones. It is the remote ones tied to a terminal panel, tucked behind another component, six inches away that create the nightmares.

Good thing it is a long Winter in these parts.


David