Hi group,
it seems that the old problem of spurious emissions on 153 kHz from Donebach
has returned this morning. At the moment, the annoying wideband-FM swish and
hiss is about 21 dBuV/m, 136km from the TX (25 mW EMRP). It is distributed
over a few kHz, depending on the modulation content, and identified best in
SSB mode. On average, my noise level is raised by 10 ... 15 dB.
These emission had suddenly increased on June 10th 2001 and were especially
strong on warm summer afternoons. After a couple of phone conversations with
an engineer at the TX site, it became clear that the Dynamic-AM modulation
controller of one of their two 250kW transmitters showed a
temperature-dependent fault. The problem could be solved on August 16th, when
the spurii were reduced to an insignificant level. Until today :-(.
Again, I would appreciate observations of others in south-west and south
Germany. For comparison, I can send a short .wav file directly to anyone
interested.
Regards
de Markus, DF6NM (JN59NK)
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