1940s modular Hell system

[Introduction]
[St.aps.31a]
[References]

Latest page update: August 2022 (updated ref. 4 pdf, associated text, Fig. 5, Fig. 6, and page title, added Fig. 7)

Previous update: 30 September 2020 (added Fig. 3-6, associated text, ref. 4); 10 February 2019.

INTRODUCTION

A 1941 Siemens-Halske patent (ref. 1) proposes a flexible modular "building block" ("Baukasten") Hellschreiber system. The concept comprises several modules (see Figure 1):

Hell-printer with motor
Vertically oriented paper-tape cassette
Keyboard-sender with built-in paper tape cassette-drawer
Punch-tape sender with built-in paper tape cassette-drawer

Fig. 1: the modular Siemens-Hell concept

(source: adapted from ref. 1)

The printer module includes the motor, so this module is always required. With it, the following three configurations can be made, by attaching one of the other modules:

Stand-alone "printer only" (item 1 in Fig. 2), as a possible replacement for the "Presse-Hell" printers.
"Printer + punch tape sender" (item 2 in Fig. 2)
Desktop "printer + keyboard sender" (item 3 in Fig. 2)

Fig. 2: three modular configurations

(source: adapted from ref. 1)

The printer-motor module in the patent has two output gears. The one on the right can drive a keyboard-sender or punch-tape-sender unit. The one on the left is for driving a callsign-generator module ("Namengeber", to transmit the station identifier). The latter is not detailed further in the patent. Note that such a callsign-generator is not particularly complicated: all it takes is a a small motorized stack of notched disks and associated switch contacts.

The same patent also also covers a portable modular printer-sender configuration with a radio/printer-amplifier module. See the "Next generation" Feld-Hell page.

THE PRINTER-PUNCH-TAPE-SENDER STATION "ST.APS.31A"

To date, only the development and production of two of the four modules can be confirmed: the motorized printer module and the punch-tape-sender module. They are part of the complete printer/sender equipment set that is referred to as "St.aps.31a". This set comprises the following items (ref. 4):

Printer/sender unit, consisting of:
Printer module St.empf.2a
Punch-tape sender St.send.1a, a.k.a. T.send.46
Power supply module St.bk.4a
In this type designator, the "bk" stands for "Beikasten" - an add-on box. It contains a simple power supply (125/220 volt AC transformer, rectifier bridge, smoothing capacitors). It has two 16-blade terminal connectors: one (male, on the side) that mates with the printer module. The the other connector (female, on top) serves to connect the cable from the keying amplifier.
Tone generator St.sum.1a
Regarding electrical circuitry and form-factor, it is a Siemens-Halske model T.sum.1, see the "Presse-Hell" tone generator section. It has an additional 16-blade connector terminal on the side, that mates with a connector on the side of the punch-tape sender, to provide it with power and connect its tone signal output without external cables.
The following tone frequencies can be selected (internal straps): 900, 1500, 2100, and 3180 Hz. It is preset to the "Hell" standard of 900 Hz.
Keying amplfier St.verst.1b
This is a Siemens-Halske model T.verst.1b, see the "Presse-Hell" keying amplifier section.
The standard Siemens-Halske keyboard punch-tape perforator T.loch.1m. , see the "Presse-Hell" tape perforator section.

Fig. 3: Complete system, referred to as "St.aps.31a"

(source: adapted from ref. 4)

The motor has a centrifugal speed regulator, similar to that of the Feld-Hell machine - but without an overspeed protection contact.

Fig. 4: Hellschreiber printer module St.empf.2a

(source: adapted from ref. 4; a second toggle switch is located below te ink roller arm, see Fig. 15)

Fig. 5: Front of the "St.send.1a" - cover removed

(source: adapted from ref. 4)

Fig. 6: Rear of the "St.send.1a" - cover removed

(source: adapted from ref. 4)

One Siemens-Halske customer for the "St.aps.31a" was the Swiss army, who procured 17 complete sets during the period 1942-1947 (ref. 4). This implies that the system components St.empf.2a, St.send.1a (T.send.46), St.bk.4a, and St.sum.1a were already developed and manufactured in 1942. It is unclear if Siemens Albiswerk Zürich AG in Switzerland was involved with the production of the system modules. This company was acquired by Siemens & Halske in 1922 as Protos Telephonwerke AG. In 1924 it was renamed to Telephonwerke Albisrieden AG, and to Albiswerk Zürich AG in 1935. They made not only civil and military telephone equipment, but also (militray) radio systems (until 1952), and Siemens teleprinters.

Fig. 7: The modular elements - combined with a radio receiver & transmitter

(source: adapted from ref. 4)

THE PRINTER-PUNCH-TAPE-SENDER UNIT "ST.EMPF.2A / ST.SEND.1A"

The German post-war news agency DANA initially operated under the direction of US Brigadier General Robert A. McClure. On 26 October 1946, DANA was officially handed over to an association of German newspaper publishers. An "St.empf.2/St.send.1a" unit was at the licensing ceremony:

Fig. 8: October 26, 1946 - licensing ceremony of DANA - with an St.empf.2a/St.Send.1a/St.sum.1a on the desk

(source: ref. 3)

Fig. 9: The "printer punch-tape-sender" configuration

(source: adapted from ref. 1)

Below are photos of some other "St.empf.2a/St.send.1a" units that have actually been in service.

Fig. 10: SH-Geber-Empfänger

Fig. 11: SH-Geber-Empfänger - restored by P. Trepte

(original unedited photo: © P. Trepte; used with permission)

The label on the front of punch-tape reader module only identifies it as an "SH GEBER-EMPF." I.e., a Siemens-Hell "Geber-Empfänger" ( = sender/printer):

Fig. 12: Label on a 1946 "SH Geber-Empfänger"

(source: courtesy P. Trepte)

The blank label (i.e., without embossed data entries) is identical to that of the Hell Feldfernschreiber, as is the drab color - it probably came from WW2 stock. There is no model number or designator marked on the label or elsewhere on the outside of the unit. However, T send 46 is marked inside the punch-tape-sender unit, on the casting of the chassis:

Fig. 13: "T send 46" boss on the cast chassis

(source: courtesy P. Trepte)

Per the label, this unit was built in 1946. The "46" in the type designator "T send 46" corresponds to this, as the year of entry into service of this model. It has a standard "Presse Hell" printer spindle module. A drawer for the roll of the printer's paper tape is located below the sender.

Fig. 14: SH-Geber-Empfänger "T.send.46" - cover removed

Fig. 15: top view of the "T.send.46" - selector bars and contacts of the character-drum clearly visible

(note the double gearing behind the motor on the far left)

The actual printer mechanism is the standard, unchanged "Presse Hell" model with the felt ink-roller on the lever above it:

Fig. 16: Close-up of the printer module with the standard "black box" Presse-Hell printer mechanism

In the photo above, two toggle switches are visible on the printer module. The up/down toggle "standby/on" switch is clearly visible at the top-right of the module. A left/right toglle switch is partly visible, just below the arm of the felt ink roller holder. It selects the system speed: 2.5 characters/sec (used when sending with a keyboard sender) vs. 5 char/sec (when sending with a punch-tape sender). As the motor in the printer module drives both the printer and the sender, both automatically run at the same speed.

On the front of the punch tape reader, note the start/stop buttons for sending the special E-shaped Feld-Hell pause-character:

Fig. 17: start/stop buttons for the E-shaped Feld-Hell pause-character

The Swiss army acquired at least one of these machines:

Fig. 18: S-H printer-punch-tape-sender of the Swiss Army

Fig. 19: S-H printer-punch-tape-sender of the Swiss Army - cover removed

There is a light-gray knurled wheel that partially sticks out of the top left of the printer-sender machine (behind the vertical lever of the printer module). This is the adjustment knob for the motor speed. Per the label, the unit is powered by 220 VAC.

Note that the printer-sender unit has the "St.bk.4a" power-supply module attached to the left of the printer module. It has binding posts on the back, for wires and banana plugs. On top of it, there is a small switch box, to toggle between sending and receiving via telephone wires.

Also note the black button with green dot at the center of the photo (also visible in other photos above, but not in the patent drawings). This is the "Morse" telegraphy key that is taken directly from the Feld-Hell keyboard.

The 1941 patent mentions one more configuration, combining three modules into a carrying case: the "printer + motor" module, the "keyboard-sender + paper tape cassette" module, and an electronics module ( = amplifier, tone-generator, power-supply). I.e., the next generation Siemens-Hell Feldfernschreiber. The patent actually references the existing Feld-Hellschreiber several times.

REFERENCES

Ref. 1: "Bildpunkschreiberstation, bei der Teile des Gerätes zu Einzelaggregaten zusammengefaßt sind" [modular Hellschreiber station], Rudolf Zimmermann, Wilhelm Heller, Otto Steiner, Siemens & Halske A.G., Reichspatentamt, Patentschrift Nr. 765857, filed: 28 November 1941.
Ref. 2: DC-DC chopper converters
Ref. 2A: "Wo steht die Wechselrichtertechnik?", H.-J. Wilhelmy, in Funkschau, Jg. 12, Heft 1, January 1939
Ref. 2B: "Repairing vibrators for DC to DC convertors", Moritz Bickel
Ref. 2C: "Die elektronische Anodenbatterie", Jochen Jirmann (DB1NV), January 2008, 8 pp.
Ref. 2D: "Die Wechselrichter und Umrichter, ihre Berechnung und Arbeitsweise" [Zerhacker], Walter Schilling, 27 May 1940, R. Oldenbourg Verlag., 160 pp., OCLC Nr. 6139075. Table of content.
Ref. 3: p. 12 in "40 Jahre dpa, DEUTSCHE PRESSE-AGENTUR GmbH", Hans Benirschke (ed.), dpa publ., Hamburg 1989, 127 pp.
Ref. 4: "Die SIEMENS-HELL-Schreiberanlage St. aps. 31a", Telefunken Zuerich AG, February 1946, 46 pp. Courtesy G. Hütter. [file size 19 MB]

Fig. 1: the modular Siemens-Hell concept

(source: adapted from ref. 1)

Fig. 2: three modular configurations

(source: adapted from ref. 1)

Fig. 3: Complete system, referred to as "St.aps.31a"

(source: adapted from ref. 4)

Fig. 4: Hellschreiber printer module St.empf.2a

(source: adapted from ref. 4; a second toggle switch is located below te ink roller arm, see Fig. 15)

Fig. 5: Front of the "St.send.1a" - cover removed

(source: adapted from ref. 4)

Fig. 6: Rear of the "St.send.1a" - cover removed

(source: adapted from ref. 4)

Fig. 7: The modular elements - combined with a radio receiver & transmitter

(source: adapted from ref. 4)

Fig. 8: October 26, 1946 - licensing ceremony of DANA - with an St.empf.2a/St.Send.1a/St.sum.1a on the desk

(source: ref. 3)

Fig. 9: The "printer punch-tape-sender" configuration

(source: adapted from ref. 1)

Fig. 10: SH-Geber-Empfänger

Fig. 11: SH-Geber-Empfänger - restored by P. Trepte

(original unedited photo: © P. Trepte; used with permission)

Fig. 12: Label on a 1946 "SH Geber-Empfänger"

(source: courtesy P. Trepte)

Fig. 13: "T send 46" boss on the cast chassis

(source: courtesy P. Trepte)

Fig. 14: SH-Geber-Empfänger "T.send.46" - cover removed

Fig. 15: top view of the "T.send.46" - selector bars and contacts of the character-drum clearly visible

(note the double gearing behind the motor on the far left)

Fig. 16: Close-up of the printer module with the standard "black box" Presse-Hell printer mechanism

Fig. 17: start/stop buttons for the E-shaped Feld-Hell pause-character

Fig. 18: S-H printer-punch-tape-sender of the Swiss Army

(©2016 M. Boesch; used with permission)

Fig. 19: S-H printer-punch-tape-sender of the Swiss Army - cover removed

(©2016 M. Boesch; used with permission)