ARRL

Secure Site Login

Forum Home - Rules - Help - Login - Forgot Password
Members can access, post and reply to the forums below. Before you do, please first read the RULES.

Strange RFI on 10 meters and 6 meters

Jun 19th 2014, 17:12

AB3FN

Joined: Jun 5th 2007, 14:11
Total Topics: 0
Total Posts: 0
I've recently started hearing noise at approximately 57.3 KHz intervals. The noise is strongest on 6 meters, slightly weaker on 10 meters, and continues to weaken all the way down to 40 meters. This seems "backwards" to other RFI situations. I plan to swap power supplies, use ferrite cores on various lines, etc., but would welcome any thoughts. Thanks.
Jun 19th 2014, 20:25

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

It is likely that you have a wire that is resonant near 6 meters, hence the strongest signal on that band. A switching supply could have a strong signal on the output, but be quiet on the input, so that the power cable going to an electrical device would be an antenna, while the much longer AC mains wiring would not.

Zack Lau W1VT
ARRL Senior Lab Engineer
Feb 6th, 09:49

WB3FTF

Joined: Jun 28th 2017, 11:29
Total Topics: 0
Total Posts: 0
I have an RFI problem on 6 meters of a noise that slowly wanders frequencies and make a noise like: "swish, swish, swich, swish, etc." Any ideas? Doug WB3FTF
Feb 6th, 13:20

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
The first thing to do is to power a receiver off batteries and cut the main breaker. The next step is to try direction finding.

https://www.nk7z.net/category/info/rfi-mitigation/i-have-rfi-series/
An SDR connected to a computer can also be useful for characterizing the noise in the time domain.

Zak W1VT
ARRL Senior Lab Engineer

Back to Top