[Lowfer] A clue about the jammer

[Garry]

Bruce, I've monitored 518 kHz since yesterday afternoon. The garbled 
text you decoded around 0500Z is from station $04E in Savannah, GA. I 
have pinned down the interference source around the mark frequency (518 
kHz -170/2Hz) as station $04G in New Orleans, LA.  As I noted at 
http://www.lwca.org/mb/index.html and David noted here, that station has 
often failed to properly shut down. But now there is a second failed 
station as well because there is also a constant carrier around the 
space frequency (518 kHz+170/2Hz).

The attached image shows the unwanted mark tone disappearing at 0900Z 
(sorry, forgot to correct spec lab for DST) when $04G begins its 
scheduled RTTY transmission, but the unwanted space tone continues and 
ruins decoding. Around 0917Z the strong mark tone returns when $04G 
finishes its traffic (yes, as usual it exceeds the 10 minute assigned 
window).

I see a clear drop in the low tone interference level when I aim a loop 
at about 95 degrees. That's consistent with New Orleans being the source 
since its true heading is 186 degrees. I also see a drop in the high 
tone interference level when aimed at 0 degrees, implying it's coming 
from the east, but the null direction isn't clear cut and I don't really 
know the source. It's present here even in daylight. Perhaps you or 
others to the east can firmly identify it.

73, Garry, K3SIW, EN52ta, Elgin, IL

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