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Mystery signals 53.335kHz harmonics

Nov 11th 2013, 06:28

K3KXJ

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
For some time, I've been getting carriers at intervals of 53.335kHz in and around the 7MHz ham band. Tonight I'm hearing them at 7.14703MHz +/- multiples of 53.335kHz. I only hear these signals during night hours. I have not tried to determine the total frequency range affected, but it is considerably wider than the 7MHz band. Tonight the signals are S8 in the 7MHz band. This is not an artifact of my receiver, as both the Elecraft K3 and the Drake R8 receive the same signals at the same frequencies. My antennas are a Cushcraft R7 vertical and a 75ft B&W broadband folded dipole.

I've turned off the few Compact Fluorescent lights in our house, and disconnected the 3 dimmers, and it made no difference. The signals show a little QSB, though not as much as ham signals from respectable distances. This looks to me like they originate locally rather than getting here via ionospheric propagation.

Has anybody else observed these signals, and does anybody know what they are?

Tnx & 73,
John K3KXJ
Jun 17th, 19:35

AC0XU

Joined: Oct 30th 2011, 02:35
Total Topics: 0
Total Posts: 0
This is typical of noisy switching power supplies. The signal gets into house wiring, plumbing, coax, etc and can be difficult to DF. Power off everything at the main breaker in your house. Run your radio by battery - if you are still seeing the RFI then it is not coming from your house equipment. If the RFI goes away, turn on the breakers one by one until you track down the culprit.

I have seen this kind of RFI from cable modems, satellite TV equipment, and other folks have reported it from lighting systems, electric blankets, fence chargers, and wall warts.

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