Sec.  101.131   Transmitter construction and installation.

   (a) The equipment at the operating and transmitting positions must be so
   installed and protected that it is not accessible to, or capable of being
   operated by, persons other than those duly authorized by the licensee.

   (b) In any case where the maximum modulating frequency of a transmitter is
   prescribed by the Commission, the transmitter must be equipped with a
   low-pass or band-pass modulation filter of suitable performance
   characteristics. In those cases where a modulation limiter is employed, the
   modulation filter must be installed between the transmitter stage in which
   limiting is effected and the modulated stage of the transmitter.

   (c) Each transmitter employed in these services must be equipped with an
   appropriately labeled pilot lamp or meter which will provide continuous
   visual indication at the transmitter when its control circuits have been
   placed in a condition to activate the transmitter. In addition, facilities
   must be provided at each transmitter to permit the transmitter to be turned
   on and off independently of any remote control circuits associated
   therewith.

   (d) At each transmitter control point the following facilities must be
   installed:

   (1) A carrier operated device which will provide continuous visual
   indication when the transmitter is radiating, or, in lieu thereof, a pilot
   lamp or meter which will provide continuous visual indication when the
   transmitter control circuits have been placed in a condition to activate the
   transmitter; and

   (2) Facilities which will permit the operator to turn transmitter carrier on
   and off at will.

   (e) Transmitter control circuits from any control point must be so installed
   that grounding or shorting any line in the control circuit will not cause
   the transmitter to radiate: provided, however, That this provision will not
   be applicable to control circuits of stations which normally operate with
   continuous radiation or to control circuits which are under the effective
   operational control of responsible operating personnel 24 hours per day.