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The SGC Building, 13737 S.E. 26th St. Bellevue, Washington 98005 USA
P.O. Box 3526, 98009 Tel: (425) 746-6310 Fax: (425) 746-6384
© 1997 SGC Inc.
The military, marine, and aeronautical services typically operate on specific channels.
A channel is a frequency that has been chosen for specific operations. For example, the
television and CB channels are all frequencies that are spaced a certain distance to avoid
interference with each other. In these circumstances, it is easier to flip through the
channels, rather than have a standard tuning dial to adjust and readjust. HF transceivers for
these purposes have certain channels to flip through, which makes operation, especially for novices, easy.
One of the important, but often neglected, aspects of HF communications is the power supply (both the actual
power supply of the transceiver and the power source that provides power to the power supply). Most modern
transceivers run on 12 Volts DC (direct current). With the exception of AC mains power supplies, many other
systems directly supply suitable DC voltages to run a radio. However, voltage regulators
might be necessary for solar and wind-powered systems because their regulation is
difficult. Solar, wind, and human-powered systems are all interesting because they can
provide a creative and cost-effective approach to powering an HF station.
Another important consideration is how the power is moved from the power supply to the radio. This route can
have a very high impact on radio performance--especially when transmitting.
Regardless of the type of power supply used, you should design cabling from the power supply to the radio to
minimize the voltage loss. This loss occurs because wire is not a perfect conductor of electricity. The longer the
distance between a power supply and a radio, the greater the voltage drop will be.
SGC does not recommend placing a power supply more than 25 feet from a radio.
There are two reasons for this: First, the voltage drop that is experienced over 25 feet,
even when large conductor cabling is used, is not acceptable because the performance
(such as a lowered transmitter output power) can decline. Second, the longer the power
cabling, the more chance that it will fail because of any number of unforeseen circumstances.
The electricity in wire behaves somewhat like water in a garden hose. The pressure of the water is analogous to
Most modern SSB
transceivers run on
12 volts DC.
POWER SUPPLIES
CABLING
Keep the Power Supply
within 25 feet of the
radio, preferably
within 6 feet.
CHANNEL OPERATION
Channel Operation: A
frequency that has
been chosen for
specific operations
(military, marine, etc.).
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