{"data":{"id":"us/47-cfr-87.71","jurisdiction":"us","citation":"47 CFR 87.71","heading":"Frequency measurements.","body":"A licensed operator must measure the operating frequencies of all land-based transmitters at the following times:\n(a) When the transmitter is originally installed;\n(b) When any change or adjustment is made in the transmitter which may affect an operating frequency; or\n(c) When an operating frequency has shifted beyond tolerance.","path":["Title 47—Telecommunication","CHAPTER I—FEDERAL COMMUNICATIONS COMMISSION","SUBCHAPTER D—SAFETY AND SPECIAL RADIO SERVICES","PART 87—AVIATION SERVICES","Subpart C—Operating Requirements and Procedures"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-47.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:28Z","sha256":"f8fecc99026f114d4b9c36323eb447d81270bd9550d4ec96da6f8aaedd8692c3","source_id":"us-cfr","stale":true,"prev":"us/47-cfr-87.69","next":"us/47-cfr-87.73"},"notice":"GroundRules: Original legal text. Not legal advice."}