Wireless Set No. 52 Canadian - Project

[Mike K]

Originally Posted by Bruce Parker

Yet when I look at the pics I see all the old original paper components.

I noticed the same issue. Those old capacitors will not be reliable, they need to be replaced. I also don't like the exposed high voltage terminals on the power supply , over 500 Volts

The Wattmeter is not to be believed - it will be adding up and displaying all of the harmonic and spurious content of the transmitter, giving a false reading. The load impedance needs to be matched to the output impedance of the set otherwise there will be a false indication of the actual power output.

[David Dunlop]

Hi Bob.

I did see this one. Pretty nice looking Northern Electric from the outside and showing all the usual Mods with an interesting bit of service History, if the case is original to the set.

According to the Sellers description, all original caps and resistors were replaced, but the old ones were all left in situ and merely disconnected. I could see that working in Receive Mode but I am not sure i would trust modern, caps and resistors designed for solid state voltages with 80 year old valve driven equipment putting it into Transmit Mode for any length of time..

Lots of photos posted but I cannot see any modern caps of equivalent design to the original paper ones anywhere. Either they are all extremely well hidden, or perhaps small, button style were used and hidden under the originals.

Any interesting curiosity, but I would pass on it.


David

[Bob Carriere]

....had another closer look at the guts......and can't see where any modifications or parts replacement were done....... all the large paper condensers and not one "new" item added.......

Buyer beware!!!!!!

Bob C

[Bruce MacMillan]

having had a close look I can see many black Sprague TVA Atom series caps. These are fairly modern so I suspect some recapping has occurred.

[Mike K]

Originally Posted by Bruce MacMillan

having had a close look I can see many black Sprague TVA Atom series caps. These are fairly modern so I suspect some recapping has occurred.

Yes didn't spot those. Higher voltage rated axial packaged caps are becoming harder to find, the old stock new in the package capacitors or NOS can cause problems too - years of storage can degrade the dielectric materials. You can now buy modern made Chinese poly caps in axial form but they are usually a bright yellow colour ! I have noticed a Ebay seller here based in Canberra sells them in black.

In order to retain the original appearance, I have seen restorers resort to methods like drilling out the old caps and then placing a modern cap inside the old original.

[David Dunlop]

Hello Mike.

That may very likely end up being the way I go when it comes to a closer look at the paper caps in my 52-Set.

Have you ever noticed the cardboard ends on those old caps are folded in, in a manner very similar to what used to be accomplished with the reloading tools used with the old cardboard shotgun cartridges years ago? Down around the 410 size, or maybe even the cartridge size used in the wartime 2-inch Mortar rounds.

David

[David Dunlop]

Although the warmer weather re-activates all the exterior chores around ones home, it is still a perfect time to be sanding down old lead based paints outdoors. Better out than in they say, so I have now started restoration of my good Case, Spares for the 52-Set.

I thought it would be good to start with how the Case, Spares looks at the moment and these first three photos show the smaller left compartment which only has KimPak padding on the bottom of it (Not sure yet what was stored there.), the larger compartment on the right, which was fully padded and held the spare valves for the Main 52-Set, and the fully padded inside of the lid. Neither this Case, or my much rougher grey one, show any signs of a Contents List ever being glued anywhere on the inside. If anyone has such an original list, please contact me. It is possible this list my have existed in a free standing form as a folded sheet placed in the larger compartment with the valves.


David

[Chris Suslowicz]

Originally Posted by Mike Kelly

I noticed the same issue. Those old capacitors will not be reliable, they need to be replaced. I also don't like the exposed high voltage terminals on the power supply , over 500 Volts

The Wattmeter is not to be believed - it will be adding up and displaying all of the harmonic and spurious content of the transmitter, giving a false reading. The load impedance needs to be matched to the output impedance of the set otherwise there will be a false indication of the actual power output.

It's a very nice power supply, just missing the perspex/plexiglas sheet over the terminal strips and suitable DANGER - HIGH VOLTAGE labels.

As for the output power measurement, the EMERs specify a dummy load of (I think) 10 ohms and 30pF (plus a thermal ammeter) connected to the variometer output terminal in order to simulate an 8-foot whip aerial. Even that will include any harmonics, and you'd need modern test gear (spectrum analyser) to get any idea of the actual useful signal output - especially if using wire aerials or a different length of whip.

Chris. (I've got the "Dummy Aerial Set", but not the original Valve Voltmeter used with it (which is a little on the bulky side). Might try it with a later one at some point.)

[Mike K]

This is a good article by Dave Lawrence. From what I have read about variometers, they are not ideal in a electrical sense , the rotary inductor or roller tuner is a better method of electrically adding length to the antenna.

https://www.qsl.net/ve3bdb/antmeas.html

These days, you can buy a nanoNVA device for hobby use. The VNA has the ability to analyze the complex impedance of the 19 set variometer and antenna and give a direct result in various forms. The nanoVNA are easy to buy on most of the popular retail platforms . And small spectrum analyzers are available for hobby use as well.

https://www.aliexpress.com/item/1005...d=gkAQdhUhNQmF

https://www.aliexpress.com/item/1005...170019037756_1