INSTALLATION
MOBILE STATIONS
406 ENVOY™ TRANSCEIVER REFERENCE MANUAL
On-air testing
On-air testing gives a better indication of antenna operation, particularly if the
operator is familiar with the signal strengths normally received within an HF
communication network. Certain types of test calls can be used to test the installation.
With on-air testing, the difference in equipment between stations must be taken into
account when determining the quality of the transmission. For example, a 100 W
mobile station may be in contact with a base station using a full-size antenna and
high-power transceiver.
Any testing on an automatic tuning antenna should be made on all frequencies of
operation. A failure to tune on a particular frequency indicates the antenna base
impedance at this frequency has pushed the VSWR outside the acceptable tuning
range.
This may be corrected by:
• improving or extending the existing earth system
• altering the length of the coaxial feeder cable (only if the VSWR measurements
were made at the transceiver rather than the base of the antenna)
NOTE: It is recommended that the VSWR measurements are made at the base
of the antenna. In this case, altering the feeder length has little effect.
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