QST de W1AW
ARRL Bulletin 22 ARLB022
>From ARRL Headquarters
Newington CT June 30, 2016
To all radio amateurs
SB QST ARL ARLB022
ARLB022 FCC's OET Clarifies Emissions Compliance Testing for RF LED
The FCC's Office of Engineering and Technology (OET) has clarified
that all RF LED lighting devices falling under Part 15 rules as
'unintentional radiators' must meet conducted and radiated emissions
limits set forth in those rules.
'Operation of Part 15 unintentional radiators is subject to the
condition that no harmful interference is caused,' the OET reminded,
in a knowledge database paper released on June 17. 'Manufacturers
and users should therefore note that lighting devices are required
to cease operation, if harmful interference occurs.'
The OET said radiated emissions measurements must be performed at
least from 30 MHz to 1000 MHz to adequately demonstrate compliance
with Part 15 (15.109). Its guidance, the OET continued, applies to
RF LED lighting devices that, in the past, have been considered to
operate on frequencies below 1.705 MHz. Previously, devices
operating between 9 kHz and 1705 kHz had to be tested only for
radiated emissions up to 30 MHz, where no specified radiated
emissions limits exist, and were exempt from testing from 30 MHz to
1000 MHz. The OET said it recognizes that routine radiated emissions
measurements are needed under Part 15, based on the highest
frequency generated or used in the device.
'[W]e have found that emissions from RF LED lighting devices are
non-periodic, broadband in nature, and are produced as a byproduct
of the internal driver circuitry within the RF LED lighting device,'
the OET 'knowledge database' paper said. 'These types of emissions
have adequate energy and potential to generate radiated emissions
well above 30 MHz.'
The ARRL Lab's Electromagnetic Compatibility Engineer Mike Gruber,
W1MG, said he was pleased to see the FCC's OET clarify the test
measurement requirements. He said ARRL is generally hearing more RFI
complaints stemming from RF LED bulbs.
'Not only are the emissions limits higher for Part 15 LED bulbs - as
opposed to Part 18 fluorescent and CFL bulbs, they seem to be
winning out in terms of consumer popularity,' Gruber said. 'Higher
limits and more bulbs probably make for more complaints.' Gruber
said the Lab has seen LED lighting devices causing problems in the 2
meter band. 'Since conducted emissions limits do not apply above 30
MHz, radiated emissions limits can be the first line of defense
against RFI at these higher frequencies.'
Gruber pointed out that noise generated by street and traffic
lighting can be widespread. In such instances, he suggested that
Part 15b limits for residential areas should apply. 'These limits
are lower than Part 15a limits, which are intended only for
commercial and industrial environments,' he explained. 'This is
especially critical in cases where a pole transformer connected to
the lighting device also feeds a home or residence. The 240 V
split-phase secondary system can conduct RF into a residence through
the service entrance panel.' He suggested that the lower limits may
benefit mobile users.
The OET noted that the ANSI Accredited Standards Committee C63-EMC
is drafting measurement procedures for lighting devices. 'When
complete, we expect it will address in greater detail the
measurement procedures and configurations to be used in determining
compliance,' the OET said.
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