Millions of people in Yorkshire will be unable to watch daytime television for up to two weeks while work is carried out on the Emley Moor transmitter.
The 256m-high tower, near Huddersfield, is running on reduced power while aircraft warning lights are installed.
Analogue television services will be affected from 0900 to 1500 BST.
National Grid Wireless said it hoped to complete the work by Friday but it could last until 4 August if the weather conditions deteriorated.
About five million people could lose their analogue services, but cable and satellite signals should not be affected.
The work has been planned to avoid major events that are covered on television and will only be carried out on weekdays, the spokesman added.