Swiss PTT Model 50 desk phone

[countryman]

I just got this phone. I snagged it for 18 Euros delivered on a classified ad site. It's in nice condition and has it's original plug. The model was made from 1954 on, mine is from 1973 and made by Zellweger Uster AG. (Uster is the name of a town). It's a conventional design altogether, but with a plastic shell. I guess it is ABS? As it may be expected from Swiss workmanship, everything is solid and high-quality. The Model 50 was used extensively in Switzerland, but only there. Switzerland had an independent telephone industry and did not share many designs with it's neighbours. The "Zenith" dial with it's cam wheel mechanism for example is very uncommon in continental Europe. It runs smooth and effortless though and -of course- tested perfectly in the first attempt.
The handset caps look like there was a cover missing or something. But they are just like this...
The phone has a lot of capacitors and coils inside. In the lower left part of the diagram there is a high frequency filter visible. It's there to separate telephone audio and cable radio channels, the Swiss "Telefonrundspruch". Users could connect the antenna plug of a long wave AM radio to the line and receive up to 6 channels in (for AM!) high quality between 175 and 340 kHz. This was an easy way to supply radio programs to remote alpine valleys. It was used from1940 to 1997.

[tubaman]

That's a very pretty little phone in two-tone grey. At €18 delivered I think you need to add it to Find Of The Month.

[Key2871]

That actually looks pretty cool. And that plug! Boy they aren't messing around, that's rugged.

[RB]

The details are awesome.
Very well done

[LarryInMichigan]

I have a similar looking Swiss phone in brown bakelite.  There was a discussion about it several years ago here: forum link.  I just realized that the lion which is rubber stamped in a few places on this phone is the same logo that appears on a few Belgian phones that I have.  I think that we determined that the stamp had something to do with approval for use on a PABX.

Larry

[Doug Rose]

I have a similar looking Swiss phone in brown bakelite.  There was a discussion about it several years ago here: forum link.  I just realized that the lion which is rubber stamped in a few places on this phone is the same logo that appears on a few Belgian phones that I have.  I think that we determined that the stamp had something to do with approval for use on a PABX.

Larry

Nice looking phone Larry...Tis a beaut...Doug

[Stormcrash]

That's a really attractive looking phone!

Also interesting idea they had on broadcasting AM radio over the phone.  On first blush you'd think that avoiding wires in rural areas would be easier, but when you think about it they were already providing phone service and in far out areas where terrain or distance would require another transmitter, using the phone lines does seem a lot more cost effective

[ma_xyz]

Wow a swiss phone on CRPF - Congrats to the very nice phone!! and greetings from Switzerland :-)

some tidbits I can add:
- the "Modell 50" was developed by Autophon for Swiss PTT and then licensed from Swiss PTT to it's four telephone set suppliers Autophon, Hasler, Zellweger and Gfeller.
- In 1970 the successor "Modell 70" was introduced. They were very creative back then when defining the model names :-). But I believe manufacturing of the Modell 50 was continued up until the early 80ies.
- the "Modell 50" was supplied initially in Black, then also in Cream and somewhere in the 60ies your grey version was added, with a lighter grey for the case and a slightly darker grey for the handset.
- There was also a wall type "Modell 50" electrically identical but only offered in black, that was probably one of the most installed phones ever in Switzerland.
- The Handset is the "PTT 1946" which was allready used as an update for the predecessor phone the "Modell 29"
- The initial design used a 600ohm ringer (can be read on the diagram: "24.8.66 Wecker von 600 auf 1200"), the 1200ohm ringer was introduced to allow for parallel installation of phones or external ringers

... The "Zenith" dial ...

I believe the dial in your phone is the newer dial manufactured by "Sodeco" which was introduced in the 60ies. The "Zenith" dial used a design similar to the automatic electric dials.

... Swiss "Telefonrundspruch"...

As you mention "HF-TR" was introduced in 1940 and decommissioned by 1997 or 1998, HF-TR meaning "Hochfrequenz-Telefonrundspruch"  (High-frequency Telefon-line Radio-broadcast). There was a predecessor introduced in 1931 later called NF-TR to differentiate ("Niederfrequenz-Telefonrundspruch"  (Low-frequency Telefon-line Radio-broadcast) where the base audio signal was directly switched to the telephone line. The program selector in the CO (6 programs) could be changed by dial impulses between line and earth. The radio signal would then be interrupted when making a call.
In later year "Telefonrundspruch" was mainly used in Hospitality environments. When PTT decommissioned the service some hotels and hospitals did install there own HF-TR in-house modulator to continue using the receivers in the rooms (perhaps some are still in use).

... I have a similar looking Swiss phone in brown bakelite....

Larry: That's a cool phone. Looks to me like your phone is an Autophon Modell used in private installations (I believe Autophon did also export their solutions) which they then used as the mechanical blueprint for the PTT "Modell 50" design. The electrical design is much simpler than the "Modell 50". A rare thing. And brown Bakelite, so cool. I've never seen one of these.

sorry for the hijacking :-)
greetings
Michael

[LarryInMichigan]

Larry: That's a cool phone. Looks to me like your phone is an Autophon Modell used in private installations (I believe Autophon did also export their solutions) which they then used as the mechanical blueprint for the PTT "Modell 50" design. The electrical design is much simpler than the "Modell 50". A rare thing. And brown Bakelite, so cool. I've never seen one of these.

I am sure that mine was intended for private line use because it has the lion emblem rubber stamped onto it is a few places.  I have several phone, almost all Belgian, with that emblem on them.  We have discussed that topic here in the past, and the consensus was that it indicated some sort of certification for private systems.  My phone apparently came from a collection which was auctioned off in Chicago.  The phone was bought by an ebay seller in Chicago (who lives about a block from where my mother grew up) who listed it on ebay and sold it to me.

Larry

[Etienne]

I also have swiss PTT 50 phones, Tf-3-39-205 in black (same model as pictured above), and another one in ivory, Tf-3-39-215, which puzzles me. the hookswitch has some sort of heavy wheel attached to it, I cannot understand why. It makes the phone noisy. These phones were high quality and on the Tf-3-39-205, the hookswitch is almost silent. Then why add this?

[countryman]

Hmm I can't see what it actually does? Will it rotate when the hookswitch moves? Prevent tapping with it's inertia?

[HarrySmith]

I don't know for sure but my guess would be the handset was not heavy enough to fully engage or disengage the hookswitch?

[Etienne]

thanks for the replies. This phone was made on September 18th, 1967, though not made of ABS. The handset is quite heavy, nearly as heavy as the bakelite version. It is a heavy ivory resin, perhaps something like melamin.
The wheel has some inertia and moves when the switch does, but is not mechanically fixed to anything- just sitting on a part of the switch. It prevents from tapping, but just a little bit- and by doing that, creates as much noise as free tapping would... above pictures show wheel and switch up and down.