§  73.57   Remote reading antenna and common point ammeters.

   Remote reading antenna and common point ammeters may be used without
   further authority according to the following conditions:

   (a) Remote reading antenna or common point ammeters may be provided by:

   (1) Inserting second radio frequency current sensing device directly in
   the antenna circuit with remote leads to the indicating instruments.

   (2) Inductive coupling to radio frequency current sensing device for
   providing direct current to indicating instrument.

   (3) Capacity coupling to radio frequency current sensing device for
   providing direct current to indicating instrument.

   (4) Current transformer connected to radio frequency current sensing
   device for providing direct current to indicating instrument.

   (5) Using transmission line current meter at transmitter as remote
   reading ammeter. See paragraph (c) of this section.

   (6) Using the indications of the antenna (phase) monitor, provided that
   when the monitor is used to obtain remote reading indication of
   non-directional antenna base current, the monitor calibration can be
   independently made and maintained for each mode of operation.

   (b) Devices used for obtaining remote reading antenna or common point
   current indications, except antenna monitor coupling elements, shall be
   located at the same point as, but below (transmitter side) the
   associated main ammeter.

   (c) In the case of shunt-excited antennas, the transmission line
   current meter at the transmitter may be considered as the remote
   antenna ammeter provided the transmission line is terminated directly
   into the excitation circuit feed line, which shall employ series tuning
   only (no shunt circuits of any type shall be employed) and insofar as
   practicable, the type and scale of the transmission line meter should
   be the same as those of the excitation circuit feed line meter (meter
   in slant wire feed line or equivalent).

   (d) Each remote reading ammeter shall be accurate to within 2 percent
   of the value read on its corresponding regular ammeter.

   (e) All remote reading ammeters shall conform with the specifications
   for regular antenna ammeters.

   (f) Meters with arbitrary scale divisions may be used provided that
   calibration charts or curves are provided at the transmitter control
   point showing the relationship between the arbitrary scales and the
   reading of the main meters.

   (g) If a malfunction affects the remote reading indicators of the
   antenna or common point ammeter, the operating power may be determined
   by a method using alternative procedures as described in § 73.51.

   [ 41 FR 36817 , Sept. 1, 1976, as amended at  48 FR 38477 , Aug. 24, 1983;
    49 FR 49850 , Dec. 24, 1984;  50 FR 32416 , Aug. 12, 1985;  60 FR 55480 ,
   Nov. 1, 1995]