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General Category => General Radio Discussion => Topic started by: ultravista on June 02, 2018, 1736 UTC

Title: Rolling QRM - Grow Lights RFI?
Post by: ultravista on June 02, 2018, 1736 UTC

https://youtu.be/4XyqMayYElc

Rolling QRM. It starts fast, slows, then stops. When it stops, the interference is present for 12 hours. Some have suggested this is Grow Lights RFI.

The fast rolling begins at roughly at the 2 minute mark

It lasts approximately 5 minutes before stabilizing, just like the ARRL states.

http://www.arrl.org/grow-light-rfi

Grow lights tend to exhibit several unique and identifiable characteristics. So far, they typically produce a broad band noise, particularly across the 40m band. It propagates over much greater distances than one might expect from devices that meet the applicable FCC limits. Other clues include:

• Generally grow lights are set by a timer for 12 hours on and 12 hours off but this can vary
  

• Once you have established the turn on time, listen to the noise as the lamp turns on. It’s generally noisier with less of a flat spectrum. This generally lasts about 5 minutes until the lamp is warm

Now ... how do I locate the source in a densely populated neighborhood? Homes, homes, everywhere ..

Title: Re: Rolling QRM - Grow Lights RFI?
Post by: Pigmeat on June 02, 2018, 2352 UTC

Check my post on the other thread. Do an online search of county and state permits for legal grows in your area. If one is close, it's a prime candidate. Stay safe as your RF source may be coming from an illegal grow nearby.

Title: Re: Rolling QRM - Grow Lights RFI?
Post by: n3umw on November 13, 2018, 1723 UTC

Does anyone know of any way to cure the RFI? I have a 300W light and have to turn it off when listening to the radio. I've tried putting a couple of 31 ferrites on the AC cord at the light and it didn't help at all.

Title: Re: Rolling QRM - Grow Lights RFI?
Post by: Traveling Wave on November 13, 2018, 1825 UTC

What wattage is the light approved for ?
Did you try changing the bulb to a lower wattage?

Title: Re: Rolling QRM - Grow Lights RFI?
Post by: Josh on November 13, 2018, 2001 UTC

Some have found relief from rfi induced by touch lamps by installing ac line rated bypass caps in the lamp, I suppose this would take care of new ones too but might affect their function, dunno.

Title: Re: Rolling QRM - Grow Lights RFI?
Post by: n3umw on November 26, 2018, 1450 UTC

Adding caps is a good idea, THANKS! Three .01uF 5kv disk caps between each of the AC lines might help. Probably not room for anything bigger. The "light" is a 300W bank of LEDs.
https://www.amazon.com/gp/product/B00XC3LBI2/ref=oh_aui_search_detailpage?ie=UTF8&psc=1