User's Manual

INSTALLATION
FIXED STATIONS
382 ENVOY™ TRANSCEIVER REFERENCE MANUAL
Standing wave ratio
WARNING: Before using the antenna system see the safety information provided.
An SWR meter measures the forward and reflected powers between a transceiver and
its antenna load, and represents these in a ratio called the SWR. To ensure correct
installation, the power and SWR assessment should be performed with the transceiver
working in its normal antenna system. Press TUNE to see the SWR, then press PTT
to manually tune the antenna.
If the impedance of the antenna is equal to 50 , no power is reflected. This is the
ideal situation, which gives an SWR reading of 1:1. An SWR equal to or lower than
1.8:1 is acceptable. If the SWR is greater than 1.8:1, the ALC circuitry in the
transceiver reduces the output power. With some combinations of frequencies and
antenna design, it may not be possible to achieve the desired figure on all channels.
CAUTION: The SWR should never rise above 2:1.
Related links:
Radiation safety (non-EU installations) on page 439
Radiation safety (EU installations only) on page 437
Using SWR to test the installation
To test the installation using SWR:
 Select the highest operating frequency of the transceiver.
 Press PTT to tune the antenna.
If the antenna installation parameters are within the satisfactory operating range,
tuning will be successful and the SWR reading will be less than 2:1.
 Select the lowest operating frequency of the transceiver, then repeat the test.
 If a particular channel frequency does not tune, check the:
• length of the antenna (for long wire antennas)
• conductivity of the earthing system
• orientation of the antenna
 Alter these slightly in an attempt to achieve better tuning.