QRM on LF
Wed, 11 Feb 1998 21:09:14 -0500
has anyone heard of this new schem?
> Hello all,
> I am giving you some information about very strong signals in the
> range between 120-140 kHz originating from Germany:
> 138.820 (carrier freq with FSK bursts USB)
> The transmitter is located near Burg/Magdeburg SW of Berlin.
> It will/is(?) be used as part of an European network for power routing
> Unfortunately no more information is available right now.
> 128.930 (carrier freq with FSK bursts USB)
> Transmitter is located at Mainflingen/near Frankfurt (20 km from here),
> huge antennas, 125 kW.
> The actual centre freq of this transmitter is 129.100 kHz but the two
> transmitted frequencies are in the upper sideband with a shift of 340 cs.
> Lower freq: 128.930, higher freq 129.270 kHz (short burst). Sorry, the
> power mentioned before should be 100 kW.
> 123,700 kHz (centre freq): a wide bandwidth spectrum
> occupying the range between approx. 122.7... 123.8...(?) sorry cannot
> measure the upper edge well enough due to the enormous signal with its
> broadband information.
> Location also Mainflingen/Germany (near Frankfurt) running 125 kW into
> huge antenna.
> Both transmitters are so close to each other - as well as their frequencies -
> causing an intermodulation generated in one of the transmitters which is
> very noticeable between approx. 133.8 ...134.8... kHz.
> This is the reason why DA0LF is not able to copy any weak signals on LF.
> It is not an intermod generated in my RX! Others are hearing the intermod
> as well and they are about 200 km away from the transmitters!
> We have reported this problem to the German RegTP (new name for the
> authority responsible in DL now) asking them to help.
> Please check that situation in your countries as well, since it could
> help when someone in agreater distance complains as well.
> I want to make a statement: the German hams did not ask for 135.7 - 137.8!
> But we have to live with it at the moment until changes will be made -
> or this intermod problem disappears. The range below 132 kHz is very clean
> in DL - at least 2 kHz...
> Sorry for this information. We are the "bad guys" again...
> Peter/DJ8WL - also DA0LF on 137.1 kHz