The FCC has revised the power level thresholds to trigger a routine Amateur Radio station RF exposure evaluation, and the changes will be welcome news for most hams. When the FCC first decreed a year ago that ham radio stations would have to comply with RF exposure guidelines, it set a 50-W threshold level. The updated guidelines, announced August 25, increase that threshold level on all HF bands except 10 meters, where it remains at 50 W. The FCC made no changes in the RF exposure limits it announced last year.

The new RF safety guidelines are scheduled to become effective January 1, 1998, for Amateur Radio stations.

The FCC went along in part with a request by the ARRL to establish a sliding scale for threshold levels, depending upon frequency. The revised thresholds are 500 W for 160 through 40 meters, 425 W on 30 meters (where the maximum legal power is 200 W), 225 W on 20 meters, 125 W on 17 meters, 100 W on 15 meters, 75 W on 12 meters and 50 W on 10 meters. The threshold for all VHF bands is 50 W. On UHF, the threshold level is 70 W on 70 cm, 150 W on 33 cm, 200 W on 23 cm, and 250 W on 13 cm and above. Stations operating at or below these respective power levels are categorically excluded from having to perform a routine RF radiation evaluation. However, all stations, regardless of power level, still must comply with the RF exposure limits.

Along with its August 25 Second Memorandum Opinion and Order announcing the changes, the FCC released the "core" text of its long-awaited Office of Engineering and Technology (OET) Bulletin 65, Evaluating Compliance with FCC Guidelines for Human Exposure to Radio Frequency Electromagnetic Fields. The bulletin contains generic equations that can be used to analyze fields due to almost all antennas, although the FCC warns that "the resulting estimates for power density may be overly conservative in some cases." Hams leery of formulas might opt to wait for the easier-to-use Supplement B to OET Bulletin 65, which will include information designed specifically for evaluating Amateur Radio installations. The supplement promises to detail how hams can determine more simply if their individual stations comply with the new regulations. The FCC says the supplement will contain "information on projected minimum exclusion distances from typical amateur antenna installations." The FCC said it would issue Supplement B "as soon as a review of the current draft is complete." When it's ready, Supplement B will be available to download from the FCC's Web site (listed below). The FCC directed inquiries as to the availability of the supplement and other RF-related questions to its RF Safety Program, 202-418-2464; e-mail rfsafety@fcc.gov.

Last year, the FCC established time-averaged maximum permissible exposure (MPE) limits for RF fields in two tiers--for controlled environments (i.e., a ham's immediate household, including visitors) and uncontrolled environments (i.e., neighbors, the general public). If a routine evaluation of a ham station indicates that human exposure to RF fields could be in excess of the FCC's MPE limits, the licensee must act to correct the problem and ensure compliance. This could include changing operating patterns, relocating antennas, restricting access, changing frequency, output power or emission type or any combination of these and other remedies.

The FCC says that ham radio facilities "represent a special case for determining exposure, since there are many possible antenna types that could be designed and used for amateur stations."

The revised regulations categorically exclude most mobile installations, including those in the Amateur Radio Service, from having to comply with the RF-exposure or station evaluation guidelines. Since the FCC issued its guidelines, additional questions on RF safety have been added to the Amateur Radio examination question pool.

OET Bulletin 65 and the FCC Second Memorandum Opinion and Order are available at http://www.fcc.gov/oet/dockets/et93-62/. More details on the FCC's latest announcement on RF safety will appear in the October issue of QST. TNX: ARRL Letter

WWW: http://www.fcc.gov/oet/rfsafety

e-mail: rfsafety@fcc.gov

Editor's Note: If you have any other questions or concerns pertaining to this announcement please bring them to the next monthly meeting. We feel very confident that Richard Sandell, WK6R, would be more than qualified to help you out.