RADIO CONSIDERATIONS FOR 4X4 DRIVERS:
These high-power radios
operate on low RF frequencies, typically between 1.8 ~ 30MHz, at
RF levels of about 100W. They offer greatly extended operation,
but they do have pitfalls. The operating range varies with a local
ground-wave signal providing about 30Km radius, but this is in general
not too reliable and nor is the radio designed for ground-wave communications.
HF comes into its own with the reflected Sky-wave signal, which
signal that is reflected off the Earth’s Ionosphere, which
is constantly varying in height from above the Earth’s surface.
The RF path can be compared to a tennis ball bouncing up and down
as it is thrown hard into the ground.
The distances obtained
by HF are virtually anything from 300Km upwards but the operating
frequency (and therefore operating range) is very much influenced
by the height of the Ionosphere at the time of transmission and
therefore these radios are generally allowed to operate on three
or four frequencies to allow for the changing conditions. Weather
conditions play a major part in obtaining clear reception, as the
system is essentially an AM one. Atmospherics and Lightning would
cause difficult reception, as would electrical impulses.
Because of the need for
various operating frequencies, you will have to consider using an
“Automatic Antenna Tuner”. Each operating frequency
requires the antenna to be a certain fixed length to provide for
maximum signal transfer and also to prevent damage to the radio.
This is done either by the use of an Automatic Antenna Tuner, or
you could carry four stainless steel whips & HF Coils and change
them as you change frequency – not too practical!
HF/SSB licences, although
obtainable, are fairly restricted due to the limited number of available
frequencies. This is not a bad thing in itself, as it is comforting
to know that there might be other users on the same frequency should
you be stranded in a remote area and in need of assistance. You
are allowed to use HF across borders, provided you have the necessary
Radio Communications Licence from both Country’s Regulatory
Successful HF radio operation
requires a learning curve, but for those traveling long distances
where there is no other means of communication, it is a blessing.
Greatly enhanced RF coverage
Price, adversely affected by bad weather, long antenna/s
TK90 HF/SSB Radio