[RFI] New Noise

Frank N. Haas kb4t at arrl.net
Thu Oct 13 01:40:14 EDT 2005


If you can hear the noise during the day on 80 meters, I would be inclined 
to think that the source is within the same town. I would think that it 
would be easier to locate during the day when the signal seems weaker. If 
that's not possible, I would try doing an "expanding circle" search while 
listening to a mobile or portable receiver (assuming you can still hear it 
on such a receiver.)

When I'm faced with these situations, I use an ICOM R3 with a Miracle 
Ducker IL (Inline). The Miracle Ducker allows the receiver to hear much 
better at low frequencies with an easily managed VHF/UHF flex antenna. The 
Ducker has BNC connectors so I can't use my somewhat more sensitive 
SMA-equipped IC T90a mentioned in a previous message. I also have a loop 
antenna which fits nicely on top of the R3 or the Ducker. The loop is 
bi-directional but it's better than no directivity at all.

Since the signal has clearly identifiable and unique characteristics it 
should be easy to insure you are tracking the correct signal.

I'm curious if you can hear the signal at +/- 1.75 MHz or even +/- 875 
kHz?? If so, it may be easier to hear on your car's AM radio.

In any case, take a nice drive around the neighborhood or town and see if 
the signal is stronger elsewhere. If so, you may be able to mount a foot 
pursuit to zero in on the source.

Good luck!

Frank N. Haas KB4T

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