47 CFR § 24.135 - Frequency stability.

---
identifier: "/us/cfr/t47/s24.135"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "47 CFR § 24.135 - Frequency stability."
title_number: 47
title_name: "Telecommunication"
section_number: "24.135"
section_name: "Frequency stability."
chapter_name: "FEDERAL COMMUNICATIONS COMMISSION"
subchapter_number: "B"
subchapter_name: "COMMON CARRIER SERVICES"
part_number: "24"
part_name: "PERSONAL COMMUNICATIONS SERVICES"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "47 U.S.C. 154, 301, 302a, 303, 309 and 332."
regulatory_source: "58 FR 59183, Nov. 8, 1993, unless otherwise noted. Redesignated at 59 FR 18499, Apr. 19, 1994."
cfr_part: "24"
---


# 24.135 Frequency stability.

(a) The frequency stability of the transmitter shall be maintained within ±0.0001 percent (±1 ppm) of the center frequency over a temperature variation of −30 °Celsius to + 50 °Celsius at normal supply voltage, and over a variation in the primary supply voltage of 85 percent to 115 percent of the rated supply voltage at a temperature of 20 °Celsius.

(b) For battery operated equipment, the equipment tests shall be performed using a new battery without any further requirement to vary supply voltage.

(c) It is acceptable for a transmitter to meet this frequency stability requirement over a narrower temperature range provided the transmitter ceases to function before it exceeds these frequency stability limits.