Wireless Set No. 52 Canadian - Project

[David Dunlop]

Thanks, Chris.

When I read through the manual, I was left with the impression the Main Set Receiver and the Remote Receiver were virtually interchangeable. The only difference was the wording on their respective data plates. Wouldn’t be the first time I have been confused, however.

David

[David Dunlop]

Well, another 45 minutes of research and I think I have it sorted out.

As Chris stated, one needs +12 and the lower HT voltage (+150) feed, along with a suitable Ground/Earth connection to make the Remote Supply and the 52-Set Receiver play nice with each other. So basically three connections, either end.

The Supply Connector Cable assembly does, indeed have three tabs inside it at the receiver end box. Two feed the required plus voltages to the set. The third one goes nowhere at the receiver. Turns out this is absolutely correct for the 52-Set. Ground/Earth between the 52-Set Receiver and Remote Supply is achieved by the long burled locking screw that secures the Connector Plug to the Receiver Socket.

The mystery third tab in the Connector Cable Plug, going nowhere, is also correct. It feeds to the Aerial Terminal on the end of the Connector Cable Plug. Turns out the Connector Cable (CMC 106-560) was developed by Marconi for the Wireless Set No. 9 Mk I Cdn for it’s remote receiver. In that particular No. 9 Set Remote Receiver, that Aerial Terminal tab in the Connector Cable is functional. Totally redundant for the 52-Set Remote Receiver, but more efficient for Marconi not to bother changing the design.

Apparently there is a colour difference, however. If the cover on the back of the Remote Supply Connector Cable plug is wrinkle green, the cable was built for the WS No. 9 Mk I. If it is No. 2 Brown, the cable was part of 52-Set Cdn production.

As long as the Connector Cable is a CMC 106-560, it is good for either wireless set.

David

[Chris Suslowicz]

Ah, right... that explains my confusion.

Ron (M0WSN) has a Canadian WS9 remote receiver and has been looking for the connecting cable for a while. I thought I'd solved that problem with a box of WS52 bits from an auction, but the connectors are from the units and not the case.

I found the connectors and they're off a sender, so no use to man nor beast.

Chris.
(Also spent some time rummaging through the EMERs, trying to find the Remote Receiver section, with no success.)

[David Dunlop]

While doing a visual inspection of the chassis a little earlier, I spotted what I initially assumed was an old style solid fuse and clips assembly linked between the two Aerial Terminals and Ground. It seemed like a very odd place for a fuse initially but I didn't think much more of it, other than to make note to get back to it later and clean it off to see what rating information it was marked with. It was about 2.25 inches long and .375 inches wide. Standard fuse end caps and a brownish tan central body.

Well this afternoon I went back in to clean it up and have a closer look. Started wiping away the crude on the main body and was very surprised to discover a mirrored glass cylinder staring back at me, as per attached photo. I also became very reluctant to attempt removal of the item in case it broke.

My first thought was since it was glass, perhaps it had markings on it similar to those on glass valves, so I carefully applied some downward pressure to the nearest end cap in its clip. The oxidation accumulation between the clip and the end caps broke free and the cylinder could be slowly rotated in the clips. No markings to be found on the glass or anywhere on either end cap.

Next stop…the Circuit Diagram. A quick look at the Aerial Circuit finds a pair of small outlined half circles, curved sides facing each other across a small gap, and the words "DISCHARGE GAP" written next to it. A look at the components listed on the diagram shows no part identified as such.

So off to the main components listing in the 52-Set Manual. Nothing listed there either. Last possibility was to read through the Receiver section of the manual. And there it is, a very cryptic comment that a "gas filled discharge gap will be found linking the two aerial posts to ground".

All very well and good, but I cannot find much at all online about them, or there use in radio aerial circuits in receivers. More importantly, if one of these happens to break or stop working, how will one find a replacement? I am assuming two possibilities: (a) this item was simply missed in the components listings for the Wireless Set No. 52, or, (b) these things are tougher than God's Toenails and nobody at Marconi ever expected them to fail or break.

Can anyone shed any light on them? It might also be part of the WS No. 9 design and covered in those manuals (I'm hoping) or it was entirely new to the 52-Set design.


David

[Bruce MacMillan]

The Canadian Marconi CSR5 receiver also uses this device. It's purpose is to protect the receiver front end from damage by HV static. The one used in that receiver is described as:
antenna discharge gap Admiralty Pattern Type 8431 C.G.E.

It breaks down at 100V. It has no effect on the operation of the set. I suspect that as both sets were made by Marconi it could be the same part number.

I would guess that unlike a fuse it is a reusable part.

[Chris Suslowicz]

Originally Posted by Bruce MacMillan

The Canadian Marconi CSR5 receiver also uses this device. It's purpose is to protect the receiver front end from damage by HV static. The one used in that receiver is described as:
antenna discharge gap Admiralty Pattern Type 8431 C.G.E.

It breaks down at 100V. It has no effect on the operation of the set. I suspect that as both sets were made by Marconi it could be the same part number.

I would guess that unlike a fuse it is a reusable part.

Having noticed it on the circuit diagram while rummaging for the connector details further up the thread, it appears on the circuit diagram as "Spark Gap" and is noted in FZ522:

RECEIVER

R.F. Amplifier V1A (ARP3)

30. The input to the tuned R.F. amplifier is
taken from the P.A. tank circuit in the
sender. When the sender tank circuit is
tuned to the receiver frequency its resonant
characteristics contribute to the image
frequency attennuation and slightly to the
sensitivity. A gas-filled discharge gap,
SG1, is connected across the input terminals.

Under "Miscellaneous" in the receiver parts list it's described as:

"SG1 100W. neon discharge gap".

(I assume the 100W is a typo for 100V.)

Chris.

[David Dunlop]

Chris.

It seems a number of USAAF Command Set Receivers also used these Neon Tubes in their Aerial circuits as protection from 'external static discharge from either the aircraft or atmospheric sources". They were rated at about 60V.

David