A few weeks ago I noticed a new source of intense broadband RFI
had appeared on 160 meters and adjacent frequencies from
approximately 1500-2000 kHz. There is no trace of RFI on any
other frequencies or from any direction other than approximately
325 degrees azimuth.
This RFI is unusual, it appears to be nearly white noise with no
apparent spectral shape. I t sounds like white noise when received
with an SSB or AM detector, there is no trace of a 60 Hz component
or 60 Hz harmonics like AC power line noise and no spectral shape
like switching power supplies.
Using my 350 foot diameter 8 element 160 meter electrically
steerable 160 meter receiving array (thanks W8JI and W5ZN)
I determined that the RFI is arriving at my QTH at an azimuth
of approximately 325 degrees.
Using a Tecsun PL-660 handheld receiver, W3UR and I fairly
quickly determined that RFI source is a Travelers Information
Service transmitter near Interstate-70 on 1700 kHz about two
miles distant and at an azimuth if 318 degrees from my QTH.
The TIS transmitter has been operating for years with no trace
of RFI but obviously something has now gone badly wrong.
It uses a fifty foot vertical tuned to 1700 kHz.
The next step is to get the failed TIS transmitter turned off!
That's my task for tomorrow.
73
Frank
W3LPL
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