Dunyach & Leclert, Type 24.

[FABphones]

....can you take a photo of these side by side so I can see the differences. Are the differences subtle, because the PTT 24 and the Type 24 look the same to me. I could use a stare and compare....

Side by side photos below showing columns and dial mounts.
Type 24 on left, PTT 24 on right.

Note also the angle difference on the dials.

[FABphones]

Does the original phone have a DC receiver?

Jack

Photo below.
Does this tell you what you are looking for?

That's a nice find - well done!

.......is there any indication of a date?....

Jack

My date range guesstimate taken via the cradle shape appears to be correct. Very small markings on the handset confirm 1944.
Zoomed in view on photo below.

[Jack Ryan]

Does this tell you what you are looking for?

Yes it does - it is not a DC receiver (the receiver has a permanent magnet).

I think it was about 1934 (I should look it up but I'm going to bed instead) that the receiver changed from DC to the conventional permanent magnet type.

Thanks for that.

Jack

[Jack Ryan]

Side by side photos below showing columns and dial mounts.
Type 24 on left, PTT 24 on right.
Note also the angle difference on the dials.

That is for this particular Type 24 - others are different.

Jack

[countryman]

They were made over a long time and in countless varations.
When the receiver was changed to the normal style with permanent magnet, the circuit layout must have changed as well?
The old DC receivers were pre-magnetized by the line current going through them.

[Doug Rose]

Side by side photos below showing columns and dial mounts.
Type 24 on left, PTT 24 on right.

Note also the angle difference on the dials.

thanks CJ....now I get it. Very nice indeed!.....Doug

[loblolly986]

Nobody copied anything. The PTT24 and its handset were developed by LMT with (I suspect considerable) support from Bell/Western Electric in the US. LMT was the French Western Electric research facility.

The PTT had asked for proposals for a standard telephone and LMT wanted to be the designer and supplier of that telephone. I think Bell/WE in the US helped LMT achieve that.

Having achieved that, Bell/WE made 400 of the same handsets and used them for testing in the US. The first thing Bell/WE dropped was the French DC receiver. Then it made some transmitter changes as it iterated towards the E handset.

It was 1927 by the tine the E handset was released - over 30 years since Ericsson introduced handsets in Europe. The problem Bell had was getting a transmitter to work efficiently over long distances. I don't think the Bullet transmitter lived up to expectations as it was replaced relatively soon after it was introduced. Kellogg eventually solved the positional transmitter issue and Bell (and others) paid Kellogg for the use of the technology.

Jack

Thanks for the insight, Jack. I wasn't aware of the Bell/W.E. involvement in the development of these. I had looked at an interesting excerpt from a Bell history book regarding early Bell System handsets, posted here, but had forgotten the context you mention regarding long-distance transmission that allowed European systems but not the Bell System to adopt handsets for general use earlier.

[Etienne]

Doug,

"Marche Du" on your phones is not showing the manufacturer but the production run date. That is "Run of 25-2-1942 Lot No. 53" in the case of your base. At least that is what I believe it means.

This reply is quite old now, but "Marché du" means: Public procurement. It gives a clue about the date, but not the production date. I have a PTT 1924, Marché du 15 Août 1928, which was produced only 2 years later. On the PTT 1924, the production date is stamped on the aluminium label near to the brass manufacturer's label on the phone's base. Stamped with "LT" ("Lignes téléphoniques", the PTT agreed for this phone to be plugged to its network) and a number ("30" for instance). If you are lucky there is also the month before the year (number, too).