German T&N Telephone - Pictures Added

[LarryInMichigan]

I just bought this: ebay link for about $67 incl shipping.  I don't know if I got a great bargain, but these phones in good condition don't seem to appear very often.

Larry

[PhoneSeeker]

An interesting telephone. I don't know anything about it. Please post what you can about it. Or direct me to information source.  I'd like to learn more. Thanks

[LarryInMichigan]

The phone arrived this afternoon with no damage   It is smaller than I had imagined: about 6.5" x 5.5" x 5.5".  The bakelite is a bit dirty, but seems to be is excellent condition.  I did some quick tests with the phone and found that the transmitter was not working, and it loaded the line so much that I could not hear a dial tone from other phones on the line while this phone was off-hook.  I removed the transmitter and found that the problem was that the transmitter contacts in the handset are cleverly designed so that when the cap is tightened, the transmitter capsule pushes against one of the contacts and shorts it to the other contact!  A small piece of properly placed electrical tape solved that problem.  The sound quality of the phone is fair to good, but not what I would expect from a 1950s western European mainstream phone.  The dial works very well.  I have not yet tested the ringer.  I expect to connect a resistor in series with the ringer, and that looks like it should be easy to do.  There are three wires in the line cord.  They are connected to terminals marked "L_a", "L_b", and "W".  I am guessing the "W" is for "Wecker" (ringer).  Another terminal, not connected to anything, is marked "E".  I assume that it is "Erd" (earth/ground).  This phone does not have a ground-start button.

The cradle on this phone is not adjustable, so it cannot be converted in to a wall phone like at least one other German model.  I hope to clean it up and post some pictures soon.

Larry

[LarryInMichigan]

I found this wiring diagram on a piece of paper folded and tucked under some components.

Larry

[LarryInMichigan]

I did some experimenting with the ringer and found that it is not connected as I had hoped.  When the hook switch is in the on-hook position, L_a and W are connected directly to each other.  The total DC resistance of the ringer coils is about 630Ω.  If I want to add resistance to the ringer circuit, I will need to desolder one of the wires from the ringer coils, but that should not be difficult.  Is the the "W" terminal is intended for connecting an external ringer which is disconnected when the phone os off-hook?

Larry

[dsk]

This is a typical German diagram, and it was common with 600 ohms ringers. The load will be about 2,5-3 REN.
The resistor (100 ohms) and the capacitor forms a kind of filter for the dial pulse contacts, so modifications should be don on the ringer side of these components,
The good thing is: This ringer is sensitive still, and may ring at quite low voltages. Instead of putting in a resistor in series of the ringer, a capacitor would help to loose less power. A capacitor of 0.5 (0.47) uF will probably lower the REN no quite much, and it should ring soft and nice. (The clapper should move shorter than on a typical U.S. telephone.) To reduce the the loss at speech frequencies, you could even add 2 simple diodes in parallel, and opposite direction, and put them in series with the new extra capacitor.

dsk

[LarryInMichigan]

Below are some pictures of the phone after cleanup and polishing.  The bakelite is is amazing condition.  The lack of wear marks or scratches in the usual places and the fact that the handset caps were perfectly clean leads me to believe that this phone has had very little or no use.  The phone shell, handset, and finger wheel are bakelite, but the cradle is made of soft plastic.

Larry

[Dennis Markham]

Very nice, Larry.  It looks like brand new.

[Babybearjs]

cool pictures! though the schematics are kind of hard to read....unless you know german!

[dsk]

I have tried to "translate", some of it here.
To reduce the REN load, you could put in the circuit sketched in the upper right corner.

dsk

[Babybearjs]

larry, does it work? did you update the cord to use it here in the US??

[LarryInMichigan]

Yes, it works.  Like most of my European phones though, the sound quality from the transmitter is not great.

Larry

[unbeldi]

I did some experimenting with the ringer and found that it is not connected as I had hoped.  When the hook switch is in the on-hook position, L_a and W are connected directly to each other.  The total DC resistance of the ringer coils is about 630Ω.  If I want to add resistance to the ringer circuit, I will need to desolder one of the wires from the ringer coils, but that should not be difficult.  Is the the "W" terminal is intended for connecting an external ringer which is disconnected when the phone os off-hook?

Larry

This is the standard circuit for all S&H models and licensees.  Wires  (L)a and W should indeed be shunted when the set is on-hook, and indeed, the W terminal is for connecting an external ringer (W=Wecker).  You should only need the a and b terminals.

I have not found it necessary to modify this circuit for use on my lines and PBXs.

There were dozens of manufacturers of these telephone models. Your phone was made by a Siemens licensee, Telefonbau und Normalzeit GmbH., located in Frankfurt most likely. Look for an imprint in the Bakelite that reads 3N, which is the manufacturers identification (MPA code) by the German material testing institute. In fact each Bakelite part may have the imprint. There is another number for the material type in the same logo.  As these phones were made by so many companies, parts were often interchanged, and one may be able to test if the phone is still original.

The position of the connecting board and the induction coil is unusual though, and is reversed though from the common layout of the W48, and your line cord does not exit the phone in the rear center, as do the models starting with the W38.
Could you please show the bottom of this phone?

PS: Looking at the pictures again, this is not a licensed model, I think this is the model "Maingau" which was a separate development by the company, but it was never officially approved. It is very similar to the W48, but had to be purchased privately for PBX use or as extension phone.

[Haf]

It's a Maingau 46 by Telefonbau & Normalzeit Frankfurt.
Take a look here:

http://www.wasser.de/telefon-alt/datenbank/inhalt-download/d1000881/Maingau_46.pdf

http://www.wasser.de/telefon-alt/datenbank/inhalt.pl?tin=&kategorie=1000166&begriff=w%206

Nummernschalter= dial, different types used for that phone.

Not everything telephone related in Germany was developped by S & H

Haf