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Siemens R-II   R2
Intercept receiver - this page is a stub

The R-II or R2, was a communications intercept receiver, developed by Siemens in 1939/1940. The radio was in fact a copy of the American National HRO receiver, albeit with German valves (German: Stahlröhren), much like the Körting KST. The R-II was succeeded in 1940 by the R-IV.

Not much is currently known about the R-II, as there is no mention of it in the existing literature. The only hint to its existence was in personal notes [2] of the late Richard Auerbach (DL1FK) 1 , one of the founding fathers of the DARC 2 , that have recently be rediscovered by a collector [1]. According to Auerbach, about 50 R-II units were built for the Foreign Department (Auswertigen Dienst) and the German Secret Service (Abwehr). The following was taken from his notes:

The R-II was a copy of the National HRO receiver, developed at Siemens laboratories by Grünfeld. Instead of the original US valves (tubes), Grünfeld used German steel valves (Stahlröhren). The coil packs were inserted into the receiver from the top, rather than from the front as with the HRO. The R-II was housed in a die-cast aluminium case and used a PW-tuning unit and dial supplied directly by the National Company in the USA [3]. At the start of WWII, National stopped supplying PW-units to the Germans, and the R-II was replaced by the newly developed Siemens R-IV (1940).

So far, we've not been able to find any additional information about the Siemens R-II receiver or any other confirmation of its existence. As far as we know, there are no surving R-II units. From Auerbach's notes, it seems likely that the R-II resembled the later R-IV, which also has a die-cast aluminium case and on which the coil packs were also entered at the top (not the front). If you have any additional information or, better, a photograph of the R-II, please contact us.

 More about the later Siemens R-IV

  1. The callsign DL1FK is currently (2014) in use by someone else. The original owner however, was Richard Auerbach, who died on 19 October 1998 at the age of 89 years. His callsign was later reused.
  2. DARC is the German Amateur Radio Club.

  1. Günter Hütter, Siemens R IV featured on this page
    Personal correspondence. May 2014.

  2. Richard Auerbach (DL1FK), Notes about Siemens R-II and R-IV
    Personal notes, 17 April 1978. Retrieved June 2014. 1

  3. National Company Inc., National Precision Condensers
    Malden, Massachusetts (USA). Catalogue 1948. p. 31. 1
  1. Document kindly supplied by Günter Hütter [1].

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Crypto Museum. Created: Thursday 03 July 2014. Last changed: Saturday, 24 December 2016 - 21:26 CET.
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