9 Jan 2012

SAQ VLF 17.2kHz test 10.1.12

The historic Grimeton VLF transmission over Christmas on 17.2kHz had to be abandoned because of an equipment failure but Lars (SM6NM) says they are planning another test tomorrow (Tuesday Jan 10th) at 1330UTC.  The sequence will be "VVV VVV VVV DE SAQ SAQ SAQ" running for about 30 minutes and no message. No QSL cards will be issued this time. More details see www.alexander.n.seOne possible receiver to use is SM6LKM's simple VLF SDR that can be downloaded from http://sites.google.com/site/sm6lkm/saqrx .

This was what they said about the Christmas failure:
 
"The reason for the trouble with SAQ on Christmas Eve was most probably a damaged fuse in the excitation circuit for the 500 V DC generator. The fuse was not completely blown but measured a very high resistance (150 ohm). When we lost the excitation current to the DC generator, we also lost the control current to the choke coils in the conductors to the main motor, and thereby the speed control of the alternator was lost.  It was confusing that the problem occurred exactly when we connected the running alternator to the antenna. We were actually on air a few seconds with decreasing frequency until the antenna was disconnected by the protection circuit in the speed control.
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