Sec.  90.215   Transmitter measurements.

   (a) The licensee of each station shall employ a suitable procedure to
   determine that the carrier frequency of each transmitter authorized to
   operate with an output power in excess of two watts is maintained within the
   tolerence prescribed in  Sec. 90.213. This determination shall be made, and the
   results entered in the station records in accordance with the following:

   (1) When the transmitter is initially installed;

   (2) When any change is made in the transmitter which may affect the carrier
   frequency or its stability.

   (b) The licensee of each station shall employ a suitable procedure to
   determine that each transmitter authorized to operate with an output power
   in excess of two watts does not exceed the maximum figure specified on the
   current station authorization. On authorizations stating only the input
   power to the final radiofrequency stage, the maximum permissible output
   power is 75 percent for frequencies below 25 MHz and 60 percent of the input
   power for frequencies above 25 MHz. If a non-DC final radiofrequency stage
   is utilized, then the output power shall not exceed 75 percent of the input
   power. This determination shall be made, and the results thereof entered
   into the station records, in accordance with the following:

   (1) When the transmitter is initially installed;

   (2) When any change is made in the transmitter which may increase the
   transmitter power input.

   (c) The licensee of each station shall employ a suitable procedure to
   determine that the modulation of each transmitter, which is authorized to
   operate with an output power in excess of two watts, does not exceed the
   limits specified in this part. This determination shall be made and the
   following results entered in the station records, in accordance with the
   following:

   (1) When the transmitter is initially installed;

   (2) When any change is made in the transmitter which may affect the
   modulation characteristics.

   (d) The determinations required by paragraphs (a), (b), and (c) of this
   section may, at the opinion of the licensee, be made by a qualified
   engineering measurement service, in which case the required record entries
   shall show the name and address of the engineering measurement service as
   well as the name of the person making the measurements.

   (e) In the case of mobile transmitters, the determinations required by
   paragraphs (a) and (c) of this section may be made at a test or service
   bench: Provided, That the measurements are made under load conditions
   equivalent to actual operating conditions; and provided further, that after
   installation in the mobile unit the transmitter is given a routine check to
   determine that it is capable of being received satisfactorly by an
   appropriate receiver.