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Last page update: 20 January 2017


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INTRODUCTION

Besides Hellschreiber machines, Rudolf Hell's company also developed and manufactured equipment for Morse-telegraphy: tape printers, punch-tape senders, and a special punch-tape perforator:

  • Morseschreiber printers, such as the military models "MS 3" and MS 5". Note that some other manufacturers also made Morse-printers with an "MS" model designator.
  • Übungsschreiber and Übungsmorsescheiber Morse-training printers, such as models  "ÜS 3" and "Üb.M.Schr."
  • Morsegeber mechanical tape-senders, such as models "MG 12", "MG 22", and "MG 23". These were also Morse training equipment ("Hell-Morsegeräte für Schulungszwecke")
  • Electronischer Geber electronic tape-sender, such as model "EG 21"
  • Recorder single & dual-channel high speed printers, such as models "RC 28" and "RC 30"
  • Unterricht-Recorder Morse-training printers, such as model "UR 39"
  • Tastenlocher tape-perforator ("Wheatstone code), model "TL 1". Note that some other manufacturers also had a tape perforator model "TL 1" (though 5-bit Baudot code).

Rudolf Hell Morse

Fig. 1: civil Morse-equipment product brochure of the Rudolf Hell company

(source: ref. 1)

Note that all of the recorders print the "raw" telegraphy signals (i.e., the dots and dashes, dits and dahs) onto paper tape. They do not print decoded characters. The Hell "Schnellmorseschreiber" models (high speed recorders) were suitable for machine-sent speeds of up to 500 words per minute (2500 characters per minute). "Übungsmorseschreiber" models were used in telegraphy training classes.

Some of the Hell-Morseschreiber printers are directly based on Hellschreiber printer technology (see p. 20 in ref. 2A). This is why I decided to expand my Hellschreiber website with this page. In particular, models MS 3 and MS 5 are look-alikes of the ubiquitous WW2 military Hell-Feldfernschreiber ("Feld-Hellschreiber") machine, which is why I refer to them as "Feld-Morseschreiber".

Contrary to other high-speed Morse recorders, the Hell recorder is not a so-called "siphon recorder". The latter type uses a moving-coil galvanometer with an attached ink-filled capillary tube (ref. 3). Instead, the Hell recorder uses the tried-and-true "Hell system": a special, fast electromagnet that taps the paper tape against a continuously spinning printer wheel that is kept wet with ink.

Rudolf Hell Morse

Fig. 2: the Hell-Morse printer system

(source: Fig. 2 in ref. 2A)

However, the printer wheel is not a Hellschreiber helix, but resembles a gearwheel with the teeth set at an angle:

Rudolf Hell Morse

Fig. 3: printer wheel of the Hell Morseschreiber

(source: Fig. 5 in ref. 2A)


Rudolf Hell Morse

Fig. 4: printer wheel of a Hell Morseschreiber model "MS 5"


As soon as - and as long as - a (Morse) tone signal is received, the electro-magnet of the printer is energized, and the paper tape is pushed up against the printer wheel. Unlike the conventional Morse recorders, the signals are not printed as thin line segments on the centerline of the paper tape, but as a heavy hashed wide line (better readability):

Rudolf Hell Morse

Fig. 5: hashed dits & dahs printed with the Hell system - the paper tape moves from right to left

(source: Fig. 5 in ref. 2A)


Rudolf Hell Morse

Fig. 6: print-out of a series of Morse "V" characters on paper tape

(source: Fig. 6 in ref. 2A)


Rudolf Hell Morse

Fig. 7: printer wheel of a Hell Morseschreiber


Rudolf Hell Morse

Fig. 8: printer wheel of a Hell Morseschreiber


This may appear to be similar to the original Morse recorders of the late 1800s, but it is not. First of all, such conventional electro-magnet Morse recorders do not perform well with low signal-to-noise levels. Also, those "ticker" recorders are not suitable for high-speed Morse signals that are sent by machines. Note that a Morse telegraphy speed of 500 words/min implies a shortest pulse duration of a mere 2.5 msec. This means that the armature of the electro-magnet must move up (down) well within 1 msec as soon as the magnet is (de)energized!


HELL MORSESCHREIBER MODEL "MS 3"

As the side-by-side photos below clearly show, the construction of Hell Morseschreiber model MS 3 is similar to that of the Hell Feldfernschreiber (a.k.a. "Feld-Hell") that was developed for the German military several years earlier. Same modular design, similar die-cast electronics box, same printer box and felt ink ring, two paper trays, etc. This is why I'd like to refer to it as the "Hell Feld-Morseschreiber". Model MS 3 can handle speeds from slow hand-sent, up to an average 300 words/min (1500 characters/sec) machine-sent speed. The speed of the paper tape is adjustable between 1.5 and 10 m/min (!) - i.e., 5-33 ft/min.

Rudolf Hell Morse

Fig. 9: Hell Feld-Morseschreiber "MS 3" and Feld-Hellschreiber side-by-side

(source: Fig. 8 in Ref. 2A (left), Fig. 9 in ref. 4)

Rudolf Hell Morse

Fig. 10: Hell "MS 3a" in its carrying case

(original unedited "MS 3a" photos are courtesy Pierre Destexhe; used with permission)

The MS 3 includes a winder for the paper tape ("Papieraufspulvorrichtung") - nice to have when the tape moves at 10 m/min! It is driven by a slip-clutch pulley on the shaft of the paper transport drive, via a belt.

Rudolf Hell Morse

Fig. 11: Hell "MS3 a" in its operating position - with paper tape winder installed


Rudolf Hell Morse

Fig. 12: principle diagram of a Morse and image telegraphy printer

(source: Fig. 1 in the 1937 Hell patent 694437)

Received Morse-signals are passed through a volume-control potentiometer and a band-pass filter. The filter can be switched off, and has two selectable center frequencies: 900 Hz and 1500 Hz. The output of the filter is transformer-coupled to the first tube (valve) amplifier stage, and then transformer-coupled to a solid-state full-wave rectifier (with two Siemens "Sirutor" cuprous-oxide diodes). The rectified signal is filtered and passed to the final amplifier. The anode current of this amplifier drives the printer's electromagnet. Both tubes are of type RV12P4000. See ref. 5 for the detailed schematic. Contrary to the Feld-Hell machine, the required DC anode voltage is not generated with a motor-generator ("dynamoto"), but with a so-called "Wechselrichter" (a.k.a. "Zerhackerpatrone"): an electro-mechanical DC-DC "chopper" converter.


Rudolf Hell Morse

Fig. 13: simplified schematic of the MS3

(source: Fig. 7 in ref. 2A)


Rudolf Hell Morse

Fig. 14: the amplifier box of a Hell "MS 3a" - very similar to that of the Feld-Hell


Rudolf Hell Morse

Fig. 15: top of the amplifier box of a Hell "MS 3a"

(left-to-right: "Zerhacker" DC-DC converter, 2x RV12P4000 tubes, fuse, battery/power supply switch)


Rudolf Hell Morse

Fig. 16: label on the front of the electronics box of a 1939 Hell "MS 3a"


After World War 2, the machine shown in the photos above (serial number 2831) was used in Mexico by an engineer of the Telefunken company, to "phone home".

Rudolf Hell Morse

Fig. 17: the label of a 1940 Hell "MS 3a"


The "Tornister" carrying case of the MS 3 measures 33.6x43.6x22.2 cm (WxHxD; ≈15x17x9 inch). That is slightly smaller than the case of the Feld-Hellschreiber: 39x45.5x24 cm (WxHxD, ≈15x18x9½ inch). Including the case, the MS 3 weighs about 18 kg (≈40 lbs). A 1-page operating manual is provided in ref. 6.


HELL MORSESCHREIBER MODEL "MS 5"

Model MS 5 is a successor to the MS 3. Again, it is a military system. The audio bandpass filter is different from that of the MS 3: it has a fixed center frequency of 900 Hz, but the bandwidth is now selectable (narrow vs. wide). The circuitry still comprises two amplifier stages, but now with an RL12P10 and an RV2P2000 tube. Also, the MS 5 can operate off 12 volt DC (again, with a "Zerhacker" DC-DC power-converter for the anode voltage of the vacuum tubes), as well as 220 volt AC power. Ref. 13.

Rudolf Hell Morse

Fig. 19: Hell "MS 5" in its carrying case

(original unedited "MS 5" photos (this one and the next 3) are courtesy Pierre Destexhe; used with permission)

The two compartments above the printer/electronics module are for "Schreibpapier" (spare rolls of paper tape) and "Ersatzteile" (spare parts such as fuses and ink rollers)

Rudolf Hell Morse

Fig. 20 Hell "MS 5" - in its operating position, with its upper paper cassette pull out


Rudolf Hell Morse

Fig. 21: label on the above 1941 Hell "MS 5 "


Rudolf Hell Morse

Fig. 22: the "Zerhacker", tubes and fuse are easily accessible on top of the printer/electronics module


Rudolf Hell Morse

Fig. 23: printer module of another "MS 5"


Rudolf Hell Morse

Fig. 24: label on the front of the above "MS 5"


Rudolf Hell Morse

Fig. 25: close-up of the printer module of the "MS 5" - note the printer wheel


Rudolf Hell Morse

Fig. 26: close-up of the printer module of the "MS 5" - note the similarity with the Feld-Hell printer


Rudolf Hell Morse

Fig. 27: A "Prüfkarte" (acceptance test tag) from the Rudolf Hell factory in Berlin-Dahlem - signed in 1939



HELL ÜBUNGSMORSESCHREIBER "ÜS3"

Rudolf Hell Morse

Fig. 28: Hell Übungsmorseschreiber "ÜS 3" - front & rear view

(source: ref. 7)

As shown in the schematic below, the connectors on the rear of the machine are marked (top to bottom): "Fernhörer", "Taste", "Fremdsummer", "+ 4 Volt -", and "Netz". I.e., "phone", "key", "external tone-oscillator", "+ 4 Volt -" and "mains / AC-power":

Rudolf Hell Morse

Fig. 29: schematic of the Hell Übungsmorseschreiber "ÜS 3"


Rudolf Hell Morse

Fig. 30: a 1938 Hell Übungsmorseschreiber "ÜS 3"


Rudolf Hell Morse

Fig. 31: rear of a "ÜS 3" - cover removed


Rudolf Hell Morse

Fig. 32: "HELL ÜS 3A2" is marked on the chassis casting


Rudolf Hell Morse

Fig. 33: "HELL ÜS 3 A1" is marked on the bottom of the cast base plate



HELL MASCHINENGEBER "MG 12"

Maschinen-Geber MG 12 is a punch-tape Morse sender. Ref. 7, 8.

  • Punch tape encoding: Wheatstone-code
  • Output: on-off keyed (relay) or tone pulses
  • Built-in tone generator frequency: selectable 960, 1540, 2560 Hz
  • Telegraphy speed: 15-340 characters/min (relay), 15-480 characters/min (tone)

Rudolf Hell Morse

Fig. 34: Hell Maschinengeber "MG 12"

(source original unedited photo: eBay)


Rudolf Hell Morse

Fig. 35: Hell Maschinengeber "MG 12"

(source original unedited photo: eBay)


HELL MORSEGEBER "MG 22"

Morse-Geber MG 22 is a punch-tape Morse sender for training purposes.

  • Punch tape width: 12 mm
  • Punch tape encoding: Wheatstone code
  • Built-in tone generator
  • Telegraphy speed: 39 - 150 characters/minute
  • Compatible with the practice recorder UR 39.

Rudolf Hell Morse

Fig. 36: Hell Morsegeber "MG 22"

(source original unedited photo: eBay)


HELL DOPPEL-RECORDER "RC 28"

Model RC 28 is a 2-channel Morse printer ("Doppel-Recorder"). It has two separate keying amplifiers, each with a printer system. Both printers print onto the same paper tape. It was specially developed for diversity reception on shortwave. That is: Morse signals were sent with two simultaneous audio tones, and separated upon reception, with narrow audio filters; this improved reception quality during noise and fading. The unit includes circuitry for noise suppression, automatic gain control, and adaptation for signal time constants (fast/medium/slow). Ref. 7, pp. 60-61 in ref. 9.

  • Paper tape width: 13 mm. Tape speed is continuously variable.
  • Telegraphy speed: 15 to 480 words/minute (75 - 2400 characters/min!)

Rudolf Hell Morse

Fig. 37: Hell "RC 28"


Rudolf Hell Morse

Fig. 38: Label on the back of a Hell "RC 28"

(original unedited "RC 28" photos below: courtesy J. Fastner, used with permission)

Rudolf Hell Morse

Fig. 39: top view of another "RC 28" - cover removed


Rudolf Hell Morse

Fig. 40: rear view of an "RC 28"- cover removed


Rudolf Hell Morse

Fig. 41: close-up of the connectors on the rear of an "RC 28"


Rudolf Hell Morse

Fig. 42: close-up of the vacuum tubes at the rear of an "RC 28"



HELL DOPPEL-RECORDER "RC 30"

The RC30 is the same as the RC 28 above, but for speeds of 10-200 WPM instead of 15-480 WMP.

Rudolf Hell Morse

Fig. 43: label on a Hell "RC 30"



HELL ÜBUNGSRECORDER "UR 39"

As the name suggests, this is a recorder (printer) for Morse training purposes (Übung, Unterricht):

  • Speed of the paper tape can be varied between 1 and 3 m/min (3.3-10 ft/min).
  • Input signal level: 0.25-3 volt (-9.5 to +12dB) at 600 ohm ( = standard phone line)
  • Frequency of the built-in tone-generator: 1000 Hz.
  • Output signal level: 2 volt at 600 ohm
  • Vacuum tubes (valves): ECC91, EL90
  • Paper tape width: 9.5 mm
  • Telegraphy speed: up to 300 characters/minute
  • Size (WxHxD): 29x24x24 cm (≈11.5x9.5x9.5"inch)
  • Weight: 11 kg (≈24.3 lbs)
  • 110/125/190/220/240 volt AC

Rudolf Hell Morse

Fig. 44: Hell "UR 39"

(source original unedited photo: eBay)


Rudolf Hell Morse

Fig. 45: Hell "UR 39"

(source original unedited photo: eBay)


Rudolf Hell Morse

Fig. 46: Rear view of a Hell "UR 39 C"

(source original unedited photo: eBay)


Rudolf Hell Morse

Fig. 47: Label on a Hell "UR 39 C"

(source original unedited photo: eBay)


HELL TASTENLOCHER "TL 1"

The Hell company also made keyboard punch-tape perforators for Morse telegraphy applications, primarily with Wheatstone encoding rather than Baudot (ref. 5). The keyboard of Hell model TL 1a has 40 keys, whereas general purpose teleprinter keyboards have 50 keys. These perforators were still built in the 1960s.

  • Punch tape width: 12 mm
  • Punch tape encoding: Wheatstone code
  • Typing speed: up to 650 characters/minute
Rudolf Hell Morse

Fig. 48: Hell Tastenlocher Typ 1

(source: Fig. 264 in ref. 3)

Rudolf Hell Morse

Fig. 49: Hell Tastenlocher model "TL 1a"

(source: Fig. 43 in ref. 9)


Rudolf Hell Morse

Fig. 50: Hell Tastenlocher model "TL 1a"

(source: Fig.4 in ref. 10)


PATENTS

Patent number Patent office Year Inventor(s) Patent owner(s) Title (original) Title (translated)
682595 RP 1937 Dr.-Ing. Rudolf Hell Dr.-Ing. Rudolf Hell Schaltung für Übungsmorseschreiber mit Motorantrieb, die wahlweise aus einem Wechselstrom- oder Gleichstromnetzt gespeist werden können Circuit for motorized practice Morse recorders, that can be AC or DC powered [tone generated by motor collector]
694437 RP 1937 Dr.-Ing. Rudolf Hell Dr.-Ing. Rudolf Hell Schreiber für Morsezeichen und Bildtelegrafenimpulse printer for Morse characters and image telegraph pulses
718017 RP 1939 Dr.-Ing. Rudolf Hell Dr.-Ing. Rudolf Hell Anordnung zur Aufzeichnung mehrerer im absatzweisen Mehrfachbetrieb gleichzeitig gegebener Telegramme Device for simultaneous recording of multiple telegrams
726257 RP 1939 Dr.-Ing. Rudolf Hell Dr.-Ing. Rudolf Hell Anordung für Schreibempfänger mit selbsttätigem Anlassen und verzögertem Stillsetzen des streifens Device for autonomously starting and stopping paper tape transport of a printer

Patent office abbreviations: RP = Reichspatentamt

Patent source: DEPATISnet, the on-line public database of the Deutsches Patent- und Markenamt (DPMA, German Patent and Trademark Office)


REFERENCES


External links last checked: March 2016


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©2004-2016 F. Dörenberg, unless stated otherwise. All rights reserved worldwide. No part of this publication may be used without permission from the author.