---
kind: "section"
citation: "47 C.F.R. § 73.875"
title: "47"
number: "73.875"
heading: "Modification of transmission systems."
url: "https://uscodex.org/cfr/47/73.875"
---

# §73.875. Modification of transmission systems.


The following procedures and restrictions apply to licensee modifications of authorized broadcast transmission system facilities.

- (a) **The following changes are prohibited—**
  - (1) Those that would result in the emission of signals outside of the authorized channel exceeding limits prescribed for the class of service.
  - (2) Those that would cause the transmission system to exceed the equipment performance measurements prescribed in [§ 73.508](/cfr/47/73.508.md).
- (b) The following changes may be made only after the grant of a construction permit application on FCC Form 2100, Schedule 318.
  - (1) Any construction of a new tower structure for broadcast purposes, except for replacement of an existing tower with a new tower of identical height and geographic coordinates.
  - (2) Any change in station geographic coordinates, including coordinate corrections and any move of the antenna to another tower structure located at the same coordinates.
  - (3) **Any change in antenna height more than 2 meters above or 4 meters below the authorized value.**
  - (4) **Any change in channel.**
- (c) The following LPFM modifications may be made without prior authorization from the Commission. A modification of license application (FCC Form 2100, Schedule 319) must be submitted to the Commission within 10 days of commencing program test operations pursuant to [§ 73.1620](/cfr/47/73.1620.md). For applications filed pursuant to [paragraph (c)(1)](#c-1) of this section, the modification of license application must contain an exhibit demonstrating compliance with the Commission's radiofrequency radiation guidelines. In addition, for applications filed solely pursuant to paragraphs [(c)(1)](#c-1) or [(2)](#c-2) of this section, where the installation is on or near an AM tower, as defined in [§ 1.30002](/cfr/47/1.30002.md), an exhibit demonstrating compliance with [§ 1.30003](/cfr/47/1.30003.md) or [§ 1.30002](/cfr/47/1.30002.md), as applicable, is also required.
  - (1) Replacement of an antenna with one of the same or different number of antenna bays, provided that the height of the antenna radiation center is not more than 2 meters above or 4 meters below the authorized values. Program test operations at the full authorized ERP may commence immediately upon installation pursuant to [§ 73.1620(a)(1)](/cfr/47/73.1620.md?p=a-1).
  - (2) Replacement of a transmission line with one of a different type or length which changes the transmitter operating power (TPO) from the authorized value, but not the ERP, must be reported in a license modification application to the Commission.
  - (3) Changes in the hours of operation of stations authorized pursuant to time-share agreements in accordance with [§ 73.872](/cfr/47/73.872.md).

## Notes

### Amendments

[65 FR 7640, Feb. 15, 2000, as amended at 78 FR 66298, Nov. 5, 2013; 91 FR 29046, May 19, 2026]

### Source

Source: 65 FR 7640, Feb. 15, 2000, unless otherwise noted.

### Authority

Authority: 47 U.S.C. 154, 155, 301, 303, 307, 309, 310, 334, 336, 339.

### Amendments

[65 FR 7640, Feb. 15, 2000, as amended at 78 FR 66298, Nov. 5, 2013; 91 FR 29046, May 19, 2026]