Questions About Correct Transmitters For WE 51AL Candlesticks

[gandskueff]

I'm looking for some information about correct transmitters for WE 51AL candlesticks. I have a 51AL that has a 323 transmitter on it.  I'm wondering what transmitters the 51ALs were factory upgraded to besides with a bulldog transmitter.

Were they ever upgraded with a *329* transmitters? I know they are  called the insulated transmitter and I assume that means they have only one conductor that enters from the back of the back cup.  If this correct?  Can they also be used with the standard 2 conductor wiring?

Would anyone happen to have a picture of a *329* transmitter that could be posted so I would know if any of my transmitters are *329* transmitters.

I've got a few *329* transmitter face plates but I want to make sure I marry the correct transmitter with the *329* face plates.


Thanks a lot,
Gary

[loblolly986]

A good reference for various W.E. solid-back transmitter models, tag variations, etc., is here: http://www.classicrotaryphones.com/forum/index.php?topic=10927.0

I'll leave it to others to come up with a photo of 329 innards for reference, but the 329 is one of the early insulated models, and has a nut on the front of the diaphragm like earlier transmitters. It was superseded by the 323 (standard) and 337 (higher efficiency for long loops), which have the small embossed circle on the diaphragm instead of the nut.

"Insulated" transmitters and desk stands are the ones that use two wires to connect the transmitter. The earlier "uninsulated" models use only one wire, with the transmitter bridge, cup, and other metal components of the phone completing the other side of the circuit.

The 323 and 337 became the current models before the 51AL was introduced, so those are what they're normally found with (besides upgrades with the later 635A "bulldog" transmitter, which superceded them after the mid 1930s). In true Bell System form, though, some of these candlesticks were conversions from older/other models or otherwise assembled using remanufactured/recycled components, and the 329 was listed alongside the 323 and 337 in the AT&T Specifications (pre-B.S.P.) as late as spec. 4588 dated May 1928 (page 18), so I won't be the one to rule out untouched examples existing with older 329 transmitters that had been installed by Bell/W.E. or a field tech.

[loblolly986]

I'll leave it to others to come up with a photo of 329 innards for reference

Well, although I had looked on the forum for one, somehow it didn't occur to me to check eBay before posting that—and of course there would be listings of 329s showing the innards to be found in the completed listings, one of which is pictured below. (The rubber ring on the diaphragm was less intact on the others.) Note the wire strap installed on this specimen connecting the center terminal to one of the bridge screws, an adaptation for use as an uninsulated transmitter as prescribed on this page (source document unknown to me, but presumably by Bell or W.E.).

[TelePlay]

The 329 is basically the same as a 229 except for the insulated wire used on the 329 instead of the metal frame on the 229.

The WE 329 uses rubber washers on both sides of the metal diaphragm identical to all WE 200 series, and all other manufacturer's, candlestick transmitters (SC, Kellogg, etc).

All other WE 300 series transmitters use a single baked varnished muslin washer on the front side if the diaphragm, between the metal diaphragm and the faceplate.