AOR AR800 Operating Manual

AR8000 operating manual
111
Typical usable coverage starts from about 25 MHz and extends continuously
to 500 MHz 1300 MHz or even 2000 MHz.  The coverage peaks and dips
throughout it’s range as the elements interact to provide the widest possible
coverage.  Due to their necessary construction discone aerials are a little prone
to “wind noise” due to vibration and possible damage in severe gales.
Stub filters
Should you encounter “breakthrough” when using an external aerial (and the
attenuator does not...

AR8000 operating manual
112
This provides a screen for potential incoming interference and passes any
noise down the cable away from the receiver and toward the earth rod.
(23)  Propagation - shortwave bands
VHF and UHF transmissions generally only propagate relatively short
distances when compared to short wave signals.  For all intensive purposes
they may be considered as line-of-sight plus a bit.
Where as point to point communication between mobile users or when in built
up areas may only be a couple...

AR8000 operating manual
113
If the transmitted frequency is too high for to be reflected by the ionosphere,
or the angle too steep,  transmissions will simply pass straight though the
ionosphere without being reflected and will travel upward to the next
ionosphere layer.
“E” layer
Above the “D” layer is the “E” layer located at a height of about 100 kilometres.
The “E” layer tends not to absorb signals as much as the “D” layer but refracts
some signal back to Earth where it may be received some distance...

AR8000 operating manual
114
You will note that large areas of the Earth’s surface lays between the point of
transmission and reflection,  in this area there will be little or no reception.  For
this reason “F” layer propagation is often referred to a “SKIP” and the reflected
signal as “SKY WAVE”.
Generally speaking only frequencies below 30MHz are reflected by the
ionosphere.  Higher frequencies pass straight through even the “F” layers and
will continue outward into space for ever.
Choice of frequency...

AR8000 operating manual
115
* Specifications subject to change without notice due to continuous
development of the receiver. E&OE.
(24)  Specification
Frequency Range: 500 kHz to 1900 MHz
Receive Mode: AM, NFM, WFM, USB, LSB, CW
Frequency Step Size: 50, 100, 200, 500 Hz, 1, 2, 5, 6.25, 9,
10, 12.5, 20, 25, 30, 50, 100, 200,
250, 500 kHz or any multiple of 50Hz
up to 999.995 kHz
Receive Sensitivity:500 kHz to 2.0 MHz
SSB by field signal strength
AM   by field signal strength
2.0 MHz to 30 MHz
SSB  1.0uV...