Sec.  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  Sec. 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]