27 of 31
Testing
Note: To be conducted by qualified service personnel only.
Operation of the 2018 can be checked using an optically isolated RF current meter (contact Barrett
Communications for the appropriate equipment).
The unit consists of a toroidal sensor head attached by an optical cable to an analog meter movement.
The instrument is only capable of taking relative measurements and generally calibrated against a
known light source. It can be used to determine the magnitude of the antenna current in the radiating
arm of the antenna.
To perform the test, undo the bolt holding the high voltage cable fitted between the tuner box and the
antenna arm (at the rear). Slide the toroidal sensor over the cable and refit it securely in place. Attach
the optic fibre to the meter. Choose a frequency within the 2018's operational band, initiate a tune
sequence and observe the reading on the meter. Take measurements over the band noting the
deflection remains greater half scale of the meter display. Once tuned, key the radio and talk into the
microphone noting the deflection continues to remain within specification.
Low meter readings could be a sign of tuner failure, problems with the interconnecting cabling, poor
grounding or transceiver output.
Alternately a VSWR power meter (e.g. Bird or Daiwa CN-801 cross needle) with DC feed through
capability can be inserted in-line with the RF cable to take more accurate measurements. Ensure the
meter chosen does not bypass DC to ground.
