Last page update: 4 October 2018
©2004-2018 F. Dörenberg, unless stated otherwise. All rights reserved worldwide. No part of this publication may be used without permission from the author.
During the fall of 2011, László Veres (HA7XK), brought to my attention the existence of a Feld-Hell model that was built in Hungary. Note that this is not simply a standard German Hell Feldfernschreiber that was built during World War 2 by a Siemens-Halske subsidiary in occupied Hungary. This model actually dates to the early 1950s! However, the design, including the electronic circuitry and construction, very closely follows that of the "standard Feld-Hell".
The designator of this model is HTG-1, where "HTG" = Hellschreiber Távírógép = Hellschreiber ticker-tape machine. It was manufactured by the Telefongyár company ("Telephone Factory") in Budapest, between 1948 and 1954 (ref. 7). It is unclear if it was designed there as well.
The history of Telefongyár Rt. (TRT, Terta) goes back to the end of 1876, when János Neuhold officially registered his railway and Morse telegraphy equipment repair activities in Budapest/Hungary. During the following ten years, his repair business gradually expanded with production of telegraph equipment, a variety of small military equipment items, railway safety/signalling equipment. At that time, the company name is Vasúti szerelvény és elektrotechnikai gépgyár ("Railway assembly and electrical engineering factory"). Around 1890, he receives the first orders from the national postal company for telephones. After taking his company public 1891, the name is changed to Neuhold Vasúti Szerelvények és Elektrotechnikai Gépgyár Rt. ("Neuhold Railway Fittings and Electrical Engineering Factory"). After a steady decline in business and unsuccessful refinancing, Neuhold abandons the company mid-1894, and starts a new company later that year: Neuhold és Társa Vasútfelszerelési és Villamossági Gépgyár ("Neuhold and Co. Railway and Electrical Equipment Factory"). In 1900, they are acquired by the German company Telephon-Fabrik AG vormals J. Berliner (TEFAG, "Telephone Factory Ltd. formerly J. Berliner", founded by József Berliner, Jakob Hanover, and Hahn Miksa). Starting in the early 1900s, the Budapest company received large orders for telephone and signalling devices for the Royal Hungarian State Railway. By then, the company was commonly referred to as Telefongyár ("Telephone Factory"). János Neuhold died in 1904, while on a business trip to the Telephon-Fabrik AG head office in Hannover/Germany. His son Kornél Neuhold took over the management of the company. In 1911, Telefongyár becomes an independent Hungarian company. Its activities cover the manufacture of telecommunication and telegraphic equipment, mechanical engineering, metal industry, electrical engineering and related products.
During WW1, the company produces military items such as guns, ignition devices, snowshoes, and boots, as well as light bulbs and small radios. After the war, Hungary is occupied by the Soviet Union, and teh company is confiscated. Between WW1 and WW2, the company continues with railway signalling devices and telephones (incl. handset under license from Telefunken), and expands with batteries, radios, headphones, rail cart air brakes, fuel meters, audio recording equipment, and odd items such as potato-, tomato- and fruit-pulp thickening machines, zippers, spark plugs, refrigerators, and small boat engines. In 1928, the Standard Elektrizitätsgesellschaft (SEG, German part of the I.T.T. conglomerate) acquired a majority share in the company, but sold its share to the British Standard Co. in 1933. In 1939, the company is once again converted to produce war material, while telephone production continues. Early 1945, the company was placed under Soviet military command for about 6 months. In 1949, it was nationalized and renamed to Telefongyár Nemzeti Vállalat ("National Telephone Factory Company"), shortly thereafter simplified back to Telefongyár. Prodducts included telephone and telegraphy equipment, telephone exchanges, movie projectors, audio amplifiers, radio equipment, manufacturing machining, audio tape recorders, TVs, and pipeline inspection equipment. In 1990, Telefongyár entered into a joint venture with Siemens-Hungary. It was privatized in 1991 and became a wholly-owned subsidiary of Siemens. Ref. 8, 9. Note that Siemens & Halske already established its presence Budapest/Hungary in 1887, with a tramway company. Siemens has been present in Hugary ever since, ref. 10.
Two of these machines are in the collection of the Museum of War History (Hadtörténeti Intézet és Múzeum) in Budapest/Hungary (one is exhibited). About 15 thousand HTG-1 machines were built, but no more than about 20 are estimated to have survived (ref. 6).
THE HELLSCHREIBER TÁVÍRÓGÉP HTG-1
Fig. 1: Hellschreiber model HTG-1 (left) and the standard Feld-Hell
(all original unedited HTG-1 photos on this page: courtesy László Veres; used with permission)
Fig. 2: Hellschreiber model HTG-1 (left) and the standard Feld-Hell - paper tray cover opened
The amplifier box shows some major differences with respect to the standard Siemens-Halske Feld-Hell:
- The motor-generator turns at 3840 rpm (vs. 3600 in S-H Feld-Hell).
- The nominal generator voltage is 150 volt DC (vs. 165 in the S-H Feld-Hell)
- There is a volume control for the modulated output pulses, not only for the input signal.
- There is no rectangular bakelite connector block
- There is no 12-pin round connector, but 3 pairs of binding posts (wire or banana plug) - more practical!
- There is a 3-position toggle switch for the interface configuration / operation mode.
- The electronics are based on four tubes of type 6AU6 and 6AU8 - instead of four RV12P4000.
- The monitoring/headset output ("Mithören" in the Siemens-Halske Feld-Hell) is not transformer-isolated; instead, it is connected to the anode of the pre-amplifier tube, via a blocking capacitor.
- There is no separate phone jack for a field telephone.
- The push-button to select the range of the voltmeter (battery vs. anode voltage) is a separate switch in the front panel. In the S-H Feld-Hell, the switch is integrated in the bezel of the instrument.
- There is no equipment label with serial number, year of manufacture, etc.
Interestingly, the "battery / power-supply" toggle switch has been retained.
Fig. 3: front of the amplifier box
Fig. 4: front of the amplifier box - annotated
Fig. 5: translation of the labels & legends of the switches and connectors
Hungarian is a difficult language - for foreigners. Basically, signal names and switch positions that begin with a "K" (for "Kemény") have to do with transmitter "keying", those beginning with "M" (Modulált), with modulated tone pulses.
The two diagrams below show the close similarity between the schematics of the standard Feld-Hell and the HTG-1. A detailed schematic of the HTG-1 is provided in ref. 1A.
Fig. 6: simplified schematic of the standard Hell Feldfernschreiber
Fig. 7: simplified schematic of the HTG-1
Fig. 8: top of the HTG-1 amplifier box - tubes, fuse, and toggle switch are easily accessible
Fig. 9: labels next to the vacuum tubes in Fig. 8 above (left to right)
The 6AU6 tube is a 7-pin miniature pentode (RCA, 1953). Ref. 2. It was typically used in AF and RF amplifiers, e.g. in television sets. Equivalents are the CV2524 and EF94, and it is similar to the EF85. Tungsram in Hungary also manufactured this tube (under license). The tube has a large transconductance (4000-5000 μmho, depending on anode voltage), but a relatively low amplification factor of only 36.
- Transconductance is a measure of the change in anode current to a change in grid voltage, with anode voltage held constant; units: mho (old; "ohm" spelled backward), siemens.
- (Static) amplification is gain, expressed as the ratio of the change in anode voltage for a change in grid voltage; units: mu (μ).
Fig. 10: the "6AU6" compared to the "RV12P4000"
The 6AU8 tube is a 9-pin miniature triode-pentode (RCA, 1947). The pentode part is used for the tone oscillator. The triode part is not used. Ref. 1A.
The RV12P4000 tube of the standard Feld-hell has a large static gain (4000 max) as well as a large transconductance (2300 μmho). The Royal Hungarian Army (RHA) may also have used Tungsram tubes of type HP1220 in their German Feld-Hells, as a subsitute for the RV12P40000. The HP1220 is a high-frequency pentode with 12 volt heater voltage and 20x10=200 mA heater current.
Other components (capacitors, resistors, potmeters, possibly also the transformers) in the HTG-1 Hellschreiber were made by the company REMIX Radiotechnikai Vállalat [Radio Technology Company] in Budapest/Hungary. The company was founded in 1932 and changed its name to simply "REMIX" in 1937.
Fig. 11: rear of the HTG-1 amplifier box - cover removed
As in the Siemens-Halske Feld-Hell, all components have a small sticker with the component number from the schematic. However, here, the signal numbers are not screen-printed onto the circuit card, but stamped into the card. Resistors and diodes have a plastic sleeve.
As in the standard Feld-Hell, the vacuum tube sockets are mounted in a heavy U-shaped profile, to which the circuit card is also attached:
Fig. 12: the HTG-1 circuit card module, removed from the amplifier box
Fig. 13: the other side of the circuit card, with two audio transformers
Fig. 14: looking into the HTG-1 amplifier box from the rear - circuit card module removed
(the green and blue electrolytic capacitors are modern replacements)
Fig. 15: looking into the HTG-1 amplifier box from the rear - right-hand side of the box
(the blue electrolytic capacitors are modern replacements)
Fig. 16: looking into the HTG-1 amplifier box from the rear - left-hand side of the box
(the green electrolytic capacitors are modern replacements)
Fig. 17: looking into the HTG-1 amplifier box from the top - circuit card module removed
Fig. 18: side of the HTG-1 amplifier box with two connectors for cables to motor-generator & keyboard-drum
(same as standard Feld-Hell, though the latter also identifies each connector (and matching plug) with a colored dot)
Fig. 19: keyboard and printer-head of the Hellschreiber model HTG-1 - same as Feld-Hell
Fig. 20: Close-up of the standard Hell printer module of the HTG-1
Fig. 21: Label on the motor-generator of an HTG-1
Fig. 22: carrying case of Hellschreiber model HTG-1
During WW2, the Royal Hungarian Army (RHA) used standard German Feld-Hell machines, probably with Hungarian legends/labels:
Fig. 23: field telephone exchange unit of the Hungarian army, with "Klappenschrank" switch board and German Feld-Hell machines
(source: ref. 3, 1941)
Overall, the RHA used Hellschreibers from 1939 until 1958. The Magyar Államvasutak (MÁV, Hungarian State Railways) also used the Hellschreiber system, but with commercial "Presse Hell" printers.
- Ref. 1: "A HTG-1 távírógép műszaki leírása és kezelési utasítása" [Technical description and operating instructions of the HTG-1 tape teleprinter], issued by the Hungarian Ministry of Defence, 1954; 98 pp. price: 5 florint. (courtesy László Veres, HA7XK)
- Ref. 1A: HTG-1 wiring diagram (Figure 19 in ref. 1)
- Ref. 1B: "A 39 M. tábori távirógép részletes kapcsolása" [simplified HTG-1 schematic; lit. "Detailed wiring 39 M. of the field ticker tape"]
- Ref. 2: "6AU6 - 6AU6A", Datasheet, Tung-Sol Electric Inc., Electron Tube Division, August 1962, 4 pp.
- Ref. 3: "Bilder von der ungarischen und finnischen Nachrichtentruppe", Pleger, p. 230 in "Deutsche Nachrichtentruppen (Die F-Flagge)" [Zeitschrift für die Nachrichtentruppe und Truppennachrichtenverbände des Heeres, der Luftwaffe und der Waffen-SS - Nachrichtenblatt der Nachrichtenkameradschaften des NS-Reichskriegerbundes], Vol. 17, Issue 7, July 1941
- Ref. 4: "39 M. tábori távírógép műszaki leírása és kezelési utasítása (1942)" [Technical description and operating manual for field tape-teleprinter (1942)], Magyar Királyi Honvéd Híradó Kiképzőtábor Parancsnokság [Signal Corps School of the Royal Hungarian Army], 30 pp., 1942. The cover page of this document is here.
- Ref. 5: "Távírógép a katonai híradásban 1." [Military press tape-teleprinter], Vörös Béla, Haditechnika [Military Technology magazine], nr. 2, 1991
- Ref. 6: personal email exchange with Lázin Miklós András (HA5CBM), 5 December 2017.
- Ref. 7: "A magyar középgépipar - Hadiipar és haditechnikai termelés Magyarországon 1945 és 1980 közöt" [The Hungarian Central Machine Industry - Military and Military Technology in Hungary between 1945 and 1980], Pál Germuska, Argumentum Publishing & Printing, 2015, 613 pp.
- Ref. 8: "The Transformation of the Defense Industry in Hungary", Yudith Kiss, "brief 14" of the Bonn International Center for Conversion, July 1999, 34 pp. [pdf]
- Ref. 9: "History of the Telephone Factory from 1876 to 1991", Google-translation of the "factory history" pages of telefongyar.hu; accessed 4-Oct-2018.
- Ref. 10: "Milestones in the land of the Magyars - Siemens celebrates 130 years of success in Hungary", siemens.com global website; accessed 4-Oct-2018 [pdf]
External links last checked: March 2016