The American Radio Relay League (ARRL), the national association for amateur radio, has filed a formal complaint against a certain type of lighting system used to cultivate marijuana after determining it interferes with MF and HF radio bands.
The ARRL said that the ballasts in certain lighting devices like the Lumatek LK-1000, which are increasingly popular among marijuana growers, drastically inhibit amateur radio communications, especially in Colorado and California.
Grow lights, which consume a large amount of electricity, are integral to indoor marijuana growing operations because they allow the plants to be grown in a controlled environment, leading to the production of a higher-quality product compared to outdoor operations. Since the legalization of pot in certain states, these indoor growing systems, known as “grow houses,” have increased in number, along with the number of grow lights.
According to ARRL General Counsel Chris Imlay, “ARRL has received numerous complaints from Amateur Radio operators of significant noise in the medium and high frequency bands between 1.8 MHz and 30 MHz from ‘grow lights’ and other RF lighting devices generally…The level of conducted emissions from this device is so high that, as a practical matter, one RF ballast operated in a residential environment would create preclusive interference to Amateur Radio HF communications throughout entire neighborhoods.”
Laboratory testing completed by the ARRL revealed that the Lumatek LK-1000 did not comply with FCC standards. The Conducted Emissions Test Report that detailed the study concluded that “from the conducted emissions tests…the six highest emissions from the device in the HF band vastly exceed the quasi-peak limit specified in Section 18.307(c) of the Rules.”
“We’re not concerned about what people are using the grow lights for,” said Sean Kutzko, ARRL Media and Public Relations Manager. “We just want to make sure the manufacturers are in compliance with FCC laws.”
As Imlay put it, “Marked increases in the noise floor at MF and HF, year-over-year, are well-known to active Amateur Radio licensees, and it is devices such as the Lumatek LK-1000 and its progeny that are major contributors to this noise pollution.”
Tom Thompson, a retired electrical engineer and HAM enthusiast, experienced this noise pollution firsthand several years ago after he became unable to communicate with friends in the amateur radio community. Using a portable antenna system, he discovered the grow lights in nearby grow houses to be the source of the interference.
“I have heard radiations from these systems up to about one-half mile away,” said Thompson on his blog. “With the increase in legalized medical and recreational marijuana comes an increase in RFI due to electronic grow light ballasts. These ballasts are usually switching power supplies, capable of lighting 600 to 1000 W high-pressure sodium or metal halide lamps. The switching frequency is usually 50 to 70 kHz and is rich in harmonics.”
After procuring a lamp ballast for testing from a willing grower, Thompson developed a filter to reduce interference from the grow lights in question. He then distributed this filter to operators of nearby marijuana “grow houses” that emit interference.
“When the plants are young the lights are on 24/7,” Thompson said. “After about two weeks the lamps are on for 12 hours and off for 12 hours. The systems are usually on a timer so you can easily predict when the RFI will ensue once you have determined the turn-on time.”
In response to Thompson and the ARRL’s concerns, FCC representative Kim Hart stated that she “couldn’t address the specific complaint filed by AARL” at this time, but that “the FCC is aware of the problems caused by certain grow lights.”
-Melanie Abeygunawardana
