venerdì 6 gennaio 2012

Extra SAQ test transmission on Tuesday 10th January

Extra test transmission on Tuesday 10th January
We believe that we have found the trouble with the alternator on Christmas Eve and put it right. Probably we may use the antenna for a short while on Tuesday 10th January, so we are planning a test transmission at 13:30 UTC on 17.2 kHz CW. No message will be sent, we just send the test sequence VVV DE SAQ. We plan to be on air for half an hour, to give an opportunity to our listeners to test their equipment. Listeners'  reports will not be confirmed by QSL cards.
 
The problem with SAQ on Christmas Eve
The reason for the trouble with SAQ on Chrismas Eve was most probably a damaged fuse in the excitation circuit for the 500 V rectifier. 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 occured 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.