johnbasalla said:
How long can a station be off-air (remain dark) before they have to surrender their license or become at risk of losing their license?
Is there a difference between taking a station off-air temporarily as opposed to permanently in relation to when the FCC has to be informed? Any differences between AM and FM?
Without special authorization to do so (as in continuing to provide a subcarrier service), how long can a station have a dead carrier on-air before it becomes illegal to have the transmitter on without any modulation?
From 73.1740(a)(4):
"...the station may limit or discontinue operation for a period of not more than 30 days without further authority from the FCC. Notification must be sent...not later than the 10th day of limited or discontinued operation."
From 73.1740(c):
"The license of any broadcasting station that fails to transmit broadcast signals for any consecutive 12-month period expires as a matter of law at the end of that period, notwithstanding any provision, term, or condition of hte license to the contrary."
(the latter rule rises from an Act of Congress - the Commission cannot repeal that regulation)
So, the answer to your first question is one year. You can take a station off the air temporarily for up to a year; at that point the license is lost and the off-air condition becomes permanent... If you want to intentionally take the station off the air permanently, you can surrender the license to the FCC for cancellation.
There is no difference between AM, FM, or TV.
It's illegal to leave a dead carrier on for more than an hour, because 73.1201(a) requires an hourly station identification announcement. As long as you run an ID on the hour, it would be fine with the FCC if you ran silence for the other 59 minutes and 57 seconds.. Oh, you would also have to run the EAS Required Weekly Test and relay the Required Monthly Test. I have not heard of the FCC granting authority to operate without IDs and EAS to keep a subcarrier service on the air, but I suppose it's possible.
(I have a vague recollection of that happening with 89.7 in Miami, when they were transferred from the religious organization to Minnesota Public Radio? I wonder if they did in fact run legal IDs and the EAS stuff but were dead air the rest of the time?)