Other Features - Palstar R30A Owner's Manual

16 Radio Propagation (continued)
The upper atmosphere of the Earth contains layers of electrically
charged or ionized gasses. These ionized layers are caused by
the action of light and energy from the Sun on the atmosphere.
The ionized layers act as reflectors of radio waves, causing them
to bounce back toward the Earth. By bouncing back and forth be-
tween the Earth and the ionized layers, it is possible for radio
waves to travel all the way around the world. This is called sky
wave reception.
The study of shortwave radio propagation is a scientific discipline
in itself, but, fortunately for us, it can be simplified. Because the
nature and location of the ionized layers in the atmosphere are
caused by the action of light and energy from the Sun, it is easy to
understand that the differences vary between day and night, and
between summer and winter. In the day and during summer, radio
reflective ionized layers are at higher altitude, and the maximum
frequency that the layers will reflect (called the Maximum Usable
Frequency, abbreviated MUF) is higher. At night, and more so in
the winter when the days are shorter, the reflective layers are at
lower altitudes, and the MUF is lower. Frequencies in the lower
VHF range and higher usually penetrate right through the ionized
layers and are only able to be reflected under rare conditions.
The basics of shortwave radio propagation can be summarized in
a few statements:
1. The higher frequencies are better during daytime and in the
summer months.
2. The lower frequencies are better during night time and in the
winter months.
3. Periods of high sunspot activity favor the higher frequencies,
periods of low sunspot activity favor the lower frequencies.
4. Solar flares and other disturbances on the Sun can cause geo-
magnetic storms that upset normal propagation for hours and days
at a time. These disturbances are more frequent during times of
high sunspot activity.
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Tilt Bail - A fold-down wire bail is provided to tilt the R30A to a
more convenient angle, as illustrated on the front cover.
Internal Battery Pack - The Palstar R30A has provision for inter-
nal battery operation. Operation from the battery pack is enabled
by the Power Source switch on the back panel. The internal bat-
tery pack uses 10 "AA" size penlight cells (not provided). Alkaline
cells are recommended for maximum battery life. If rechargeable
cells such as Nicad or NiMH are used, they must be recharged in
a separate charger. Access for installing or changing the batteries
is gained by unscrewing the 6 screws located on the sides of the
unit and removing the top cover. Next, remove the battery restrain-
ing strap by removing the screw at one end and then pivot it up
until the other end unhooks. Be sure to observe proper polarity
when installing the batteries. Once the batteries are in place, se-
cure them with the battery restraining strap and replace its screw,
then reinstall the top cover.
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Other Features

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