Enclosure:   9    to Kriegstagebuch I Ship 33  
     
 
Radio Interference during the Sinking of the British
  
 
Steamer "DOMINGO DE LARRINGS/GMWK"
  
om 31 July 1940.
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          The radio interference took the form of radio traffic between the steamers ". . . . /KAFK" (not assigned) and the steamer "MARGARITA/SVMN". A Spanish and Greek name of the steamer was chosen. because  
 
1) These steamers appear in this sea area and here Spanish and Greek ships with spark gap radio transmitters were often heard on the 600-meter wavelength,
2) Because it is precisely the fist of the Greeks and often that of the Spaniards (everything run together, "smeared") that are particularly suitable for this intercourse. So the call signs could also be given so badly that different interpretations were possible, e.g. SVTG or SVOE etc.
3) Brazilians and Americans have been heard recently at the highest volume, so it was to be expected that steamers in the vicinity would intervene in traffic, so the call signs of these countries were not used.
 
  Radio communication between two steamers of different nations, i.e. international ship traffic, was chosen because others here were not sufficiently well known to set up a deceptive radio.  
          The following were used as disruptive factors:  
          In the bridge radio room the 0.5 KW spark gap transmitter as KAFK and  
          in the main radio room the 1.5 KW Marconi transmitter as SVMN.  
  At 10.24 hours ZZ (zone time) steamer DOMINGO DE LARRINAGA/GMWK transmitted on 600-meter wavelength tuning dashes of short duration afterwards the characters " Q Q " in succession.  (probably an agreed signal when approaching a suspicious ship, such as "R R").  Afterwards he gave his call sign " GMWK " and position.  When sending the first number of the position at 10.25 hours ZZ initiated the interfering radio in the form of alternating traffic between "SVMN" and "EAKK" (see enclosure).  The transmitter of GMWK was switched to "modulation - A2".  GMWK initially sent his report despite the interfering radio completely to the end.  In order not to transmit more than is absolutely necessary and to stop traffic immediately as soon as GMWK stops sending (. -...). Since GMWK was often the waiting signal  
     
     
Click the flag to view the above page from the original German KTB
     
 
- 2 -
  
     
  on its side, it waited for these pauses and then immediately tried to repeat its message, and the interference radio set in again at the same time as it did.  
          At 10.40 hours there were several dashes during the jamming traffic, probably for the auto-alarm device. The radio interference continued until GMWK was silenced by firing the first salvo. Thereupon, by giving an acknowledgment (nr 3 r r ok tu gm), the interference radio was ended at 10.57 hours ZZ.  
          Since the text at hand was not enough to interfere for more than half an hour, the interfering radio was dragged out by poor sending, constant inquiries and sticking of the key (continuous dash) with subsequent errors).  
        At 12.10 hours ZZ on 600-meters with QSA 3, this time "toneless A 1" "QQQQ" as well as the call sign "GMWK" and the position with "5.46S 18.06W.  Our interference transmitter gave a couple of key characters.  Nothing more was heard from the other station. Since, as far as was found here from and after coming alongside, the lifeboats did not have an emergency transmitter stations, it can be assumed that a steamer in Radio Message range that knew the group "QQ", which is not known in international traffic, so probably an Englishman, the "GMWK- emergency call repeated with his noon navigation fix and, in order to avoid the risk of tracking through us, did not send anything further.
        At 12.44 hours, the American "ILLINOIS / KUQU", who bearings had been taken on near us for the last few days, occupied 600 meters, gave his name and asked if something was happening. There was no answer.
          At 13.25 hours ZZ, Ascension Radio ZBI issued a GBMS with time group 1142/31 (also 10.42 hours ZZ):  
  - Encoded with Navy Merchant Code -  
  From Commander in Chief South Atlantic.  
  For (GMWK) DOMINGO DE LARRINAGA.  If you are not being fired on ship may be KLIPPAREN (Swedish Steamer) 3500 tons bound for Cape, from New York.  Make negative report if friendly identify established precipitous.  
          At 20.12 hours ZZ Freetown sent a GBMS with time group 1900/31:  
     
     
 
     
 
- 3 -
  
     
  For "DOMINGO DE LARRNAGA".  Nothing received since your description of suspicious ship.  Have you anything further to report.  From Commander in Chief South Atlantic.  
          This radio message 1900/31 was continually repeated on 1 July during the Program Time from Ascension Radio ZBI, lastly "immediately".  
          No traffic could be heard on the wavelengths observed after the sinking (600 - 800 meters, 24 meters and 18 meters), so it can be assumed that the GMWK message was not picked up by other ships.  
 
 
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
 
     
     
 
Excerpt from the Radio Message Log book (600 meters) 31.7.1940.
  
 
===============================================
  
     
10.24 hours ZZ   QQQQ  GMWK  . . . . . . . . . . .
    (interference radio)
     
10.25 hours ZZ A.) Sent long tuning dashes then . . . - .  EAFK  EAFK de SVMN
    sri sri nw nw rei 600 ii 600 k
  B.) . . . - .  SVOE SVTG de EAFK ok ok qrk?
  A.) ok - . . . - last group hr rd was hupoo ii hupoo nw go on pee qsz k +
  B.) r r - . . . - hupo hupo afkra afkra byrut byrut epbyf epbyf kyfaw kyfaw, gakra gakra bufaw bufaw gagoo gagoo ufsen ufsen uhfin uhfin erazl erazl ubteb ubteb abtaq abtaq dulfy dulfy afkra afkra diris diris
    abtaq abtaq echzy echzy eiken eiken drwry drwry + + hw
  A.) ii sri pse aa aa uhfin uhfin  ii uhfin +
  B.)  r - . . . - uhfn uhfn erazl erazl ubteb ubteb abtaq abtaq dulfy dulfy afkra afkra diris diris abtaq abtaq echzy echzy cikea cikea dywry dywry + hw
  A.) ii ii hr efm aa aa erazl 11
    erazl - . . . - ubtab ubtab abtaq abtaq dulfy dulfy afkra afkra diris diris abtaq abtaq ecszy ecszy cikca cikca dymry dymry + hw
  B.) . . . - . hr rpt last three - . . . -
    echzy echzy cikca cikca drwry drwry + hw
  A.) r r ok ok nr 2 r r tks tks +
  B.) r nw nil tu gm (gn)
  A.) gn zu
  B.) 1
     
10.57 hours ZZ   n 3 r r ok tu +
     
    Remark:  Since not yet sufficient, the traffic was still being dragged out by frequently putting out and sticking the key (continuous dash)
    The English text reads:
    Referring to the contract dating July 20 owners have agreed to payment - crew overtime only during the lay days in harbor - stop final agreement is still expected - stop further instructions will follow.
     
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
12.10 hours ZZ   QQQQ GMWK 5.46 S 18 06 W
    Interference radio key characters +
     
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
12.44 hours Z   (from American steamer "ILLINOIS/KUQM"
    CQ CQ CQ de KUQMgru?nil +