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(Refer to Selcall (Selective Call) section of this manual for full details on Beacon
Call operation.)
Time of Day
As a rule, the higher the sun, the higher the frequency that should be used. This
means that you will generally use a low frequency to communicate early morning,
late afternoon and evening, but you will use a higher frequency to cover the same
distance during times when the sun is high in the sky (e.g. midday). You will need
to observe the above rule carefully if your transceiver has a limited number of
frequencies programmed into it, as you may only be able to communicate
effectively at certain times of the day.
Weather Conditions
Certain weather conditions will also affect HF/SSB communications. Stormy
conditions will increase the background noise as a result of ‘static’ caused by
lightning. This background noise could rise to a level that will blank out the signals
you are trying to receive.
Man-made Electrical Interference
Interference of an electrical nature can be caused by overhanging power lines, high
power generators, air-conditioners, thermostats, refrigerators and vehicle engines,
when in close proximity to your antenna. The result of such interference may cause
a continuous or intermittent increase in the level of background noise.
System Configuration and Installation
The method in which your system is configured and installed will also affect the
success of your HF/SSB communications. Your choice of antenna system and
power supply is critical. Correct installation is also extremely important. An HF/SSB
transceiver is generally installed using different rules to those used to install VHF or
UHF transceivers. Failure to correctly install an HF/SSB system will greatly affect
the communications quality you will obtain. Refer to the installation section of this
manual for details.
Your local Barrett representative will be able to assist with your system
configuration and/or installation.
Special Note - HF Communications Compared with VHF or UHF Short Distance
Communications
Communications on any HF/SSB transceiver will sound different to that on a VHF
(Very High Frequency) radio or UHF (Ultra High Frequency) radio or telephone.
This is because of the nature of HF propagation and the modulation methods used.
On HF/SSB transceivers there will always be background noise evident behind the
signal you are receiving and this will increase when there is electrical interference
or thunderstorm activity in the area.
Summary of Contents for 2090
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