5
Measure the VSWR at the center of the operating
band. Tune the antenna (according to the antenna
manufacturer’s tuning instructions) so that the VSWR
is as close to 1 to 1 at the center of the operating band.
Next, measure the VSWR at the lowest and highest
frequency of the transceiver. If the antenna has a
wide enough frequency range and band-pass, the
VSWR readings should be below 1.5 to 1 across the
entire operating band. If at the lower or upper end of
the transceiver operating frequency, the VSWR
measures more than 1.5 to 1, it is recommended that
the antenna be re-tuned before operating on those
frequencies.
If you are experiencing unusual VSWR readings
check for the following possible problems:
1) Make sure that the antenna is installed properly
and grounded.
2) Check all coaxial cable and connectors for defects
and poor routing.
3) If testing a vehicle installation, make sure that all
vehicle doors are closed when testing.
4) Do not test near or around large metal objects or
buildings.
7. Ignition Noise
In certain vehicle installations, electrical noise or
interference may be present in the receive audio of
the transceiver. Typically the vehicle’s ignition system
or more specifically the alternator generates this
noise. The MAGNUM 1 is equipped with a noise
blanker circuit that is designed to reduce, and in many
instances eliminate, this electrical noise.
In extreme cases, the noise blanker may not eliminate
all the electrical noise. In such cases, an alternator /
ignition noise filter can be used. The XLF Series by
RF Limited is designed for use with the MAGNUM 1
and is an effective way to eliminate alternator and
ignition noise problems. Contact RF Limited or your
local dealer for information.
