Siemens W28 telephone
 

I found this at an antiques centre marked as a French telephone but with the Siemens and Halske logo on the back obviously of German origin. It has a metal base and bakelite top section. Looking on line there is a lot of information on the W28 series of phones but the only one with a metal body and bakelite top was one for sale in Spain with no info.
I was thinking that the markings may mean a date of around 1942 which would correspond with the glass bells, as this saved on metal for the German war effort. The early versions of the phone had a Mazak top section which had the usual Mazak problems, so could this be a wartime rebuild with a new top?
Also I was wondering what is the purpose of the white push button and the line connections labelled W2 and E on junction box? Was E a safety earth?

Re: Siemens W28 telephone
 

I imagine the button served the same purpose as similar buttons on British phones, that of "Earth Leg Recall", so two subscribers could share a line. Search this forum for "Party line".

The earth connection was therefore "Functional", but I suppose it could have been used for lightning protection as well.

Re: Siemens W28 telephone
 

W 28 made in 1942 with glass gongs, really rare! The E was for the Earth signalling not to different from the more modern R or hook-flash used to transfer. Those were used in PABX systems. These phones had a dial that would be mechanical locked when you are on hook. The w2 terminal was used for an extra ringer and should keep that one silent when you dialed. The transmitter cap would often have lost some parts, it's fragile.

Re: Siemens W28 telephone
 

Wow, glass gongs!

Re: Siemens W28 telephone
 

Thanks for the replies, the bakelite microphone housing is intact although the capsule itself is missing and the screw thread on the ring which holds the housing to the handset does not mate well with that on the handset, difficult to start and tends to cross thread (a problem which I have noticed before with other bakelite handsets).

Re: Siemens W28 telephone
 

The w28 has a 200 ohm balance resistor in the windings, this makes the transmitter's voltage pretty limited, and you have to find a Local Battery (LB) transmitter capsule to get it working well, alternativly you have to do som soldering and add a resistor or Capacitor or even better a combination, I did so with another phone based on the same circuit: http://www.classicrotaryphones.com/f...6439#msg226439

Re: Siemens W28 telephone
 

Is there a circuit diagram for this version of the phone as none of the ones I have seen seem to correspond? Also what is the 0.3uF capacitor in the capacitor block used for (RF bypass for mic? ) and what are the functions of the terminals marked F2 and the link marked " Aus Ein" at the top left of the underside photo (slightly obscured by the flash).
Mike.

Re: Siemens W28 telephone
 

"Aus/Ein" means "Out/In" (in German) if that's any help.

Re: Siemens W28 telephone
 

I thought that's what it would mean but my German dictionary says ein is one, doesn't mention in.

Re: Siemens W28 telephone
 

In the context of an electrical switch I'm sure it simply means OFF / ON

Re: Siemens W28 telephone
 

Try to look at this page. http://52608462.fn.freenet-hosting.de/portrait_w28.htm

Re: Siemens W28 telephone
 

My antivirus wouldn't allow me to view that page!

Re: Siemens W28 telephone
 

Maybe because Ein here is an abbreviation (of Eingang, entrance vs Ausgang, exit)?

Re: Siemens W28 telephone
 

try to search for W28 schaltbild or W28 shaltplan. then you should find som diagrams.

Maybe your antivirus is to strict, or maybe I took a risk. :-)

Re: Siemens W28 telephone
 

Thanks for the link Dagskarlen. I think this diagram is closest to my phone. The aus-ein link puts the 0.3u cap in parallel with the 600 ohm resistor (anti-sidetone circuit?).

Re: Siemens W28 telephone
 

Hello,

Aus/Ein definitely means Off/On in this context. Nice phone, I do have a similar one. Glass bells were said to give a smoother sound than the metal bells.

Regards, Joe

Re: Siemens W28 telephone
 

Great, and if yoou have a 600 ohms resistance between 4 and 5 on the induction coil you may us about any transmitter capsule that fits in the handset.
More easy than the more common W28 with a 200 ohms resistance and no 0.3 uF capacitor.

I really like this and I have never seen one of those before.

dsk

Re: Siemens W28 telephone
 

Ein is short for Einschalten (to switch on) and Aus for Ausschalten (to switch off).

Nandu.

Re: Siemens W28 telephone
 

Thanks for all the replies. I tried a mic capsule from an incomplete Dictaphone handset in poor condition which fitted and actually worked quite well (from the state of the handset I was surprised it worked at all!).
Mike.