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eHam Forums => Long Wave / Medium Wave => Topic started by: KG4LAC on September 06, 2022, 04:41:57 PM

Title: Terrible QRM 660 kHz until around 700 kHz
Post by: KG4LAC on September 06, 2022, 04:41:57 PM
Not in my shack.

Harmonic from power line?

Any ideas?

Title: Re: Terrible QRM 660 kHz until around 700 kHz
Post by: K7AAT on September 06, 2022, 08:23:17 PM
Get a portable AM radio and track it down....
Title: Re: Terrible QRM 660 kHz until around 700 kHz
Post by: WA7OPV on September 06, 2022, 08:41:40 PM
That is right where my fluorescent lighting used to show up when I was on those frequencies a lot.

Title: Re: Terrible QRM 660 kHz until around 700 kHz
Post by: KG4LAC on September 09, 2022, 04:35:00 AM
After turning off main power to QTH, I walked around with a portable AM radio. Still hearing QRM.

Outside, still hearing QRM.

We don't have any new fluorescent lights, but good idea and I'll keep in mind.

Next task is to walk the neighborhood to determine source of noise.
Title: Re: Terrible QRM 660 kHz until around 700 kHz
Post by: RENTON481 on September 19, 2022, 08:34:30 PM
Check individual LED lights and any CFLs. They can operate correctly and give out light OK, but still decide to spew RFI in the lower MW ranges. I have had at least 2 LED lights do that, and one CFL also did that.
Title: Re: Terrible QRM 660 kHz until around 700 kHz
Post by: KH6AQ on September 21, 2022, 07:54:16 AM
If the signal frequency drifts it is almost certainly a switching power supply.
Title: Re: Terrible QRM 660 kHz until around 700 kHz
Post by: KG4LAC on September 23, 2022, 02:05:47 PM
I found the problem. Please see post here
https://www.eham.net/community/smf/index.php/topic,137197.0/topicseen.html