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between Japan, Europe and the USA) so that the AR-ALPHA will automatically select the appropriate
tuning step size and mode for the frequency chosen. This greatly simplifies operation of the AR-ALPHA.
The factory pre-programming of step size can be manually overwritten so you may choose alternative
settings at will, or when band plans are updated.
To change the default tuning step size, press the STEP key. The frequency step will be highlighted at the
top right of the LCD (in reverse color), showing it is ready to accept a new parameter setting.
For your convenience, the following tuning step frequencies have been preprogrammed at the factory:
1, 5, 10, 50, 100, 500Hz, 1, 2, 5, 6.25, 8.333, 9, 10, 12.5, 20, 25, 30, 50, 100, 500 kHz
Rotate the sub dial to select the desired receive step. To accept the displayed tuning step size, press
the MHz key.
The tuning step size may also be programmed in 1 Hz increments (via the keypad) so that unusual step
sizes other than those stated are possible. The acceptable step size range is between 1 Hz and 1 MHz
in 1 Hz steps. Using the numeric keypad, enter the desired tuning step frequency in kHz. Then press the
MHz key to confirm entry.
2-7 IF Bandwidth
The IF bandwidth feature specifies how SELECTIVE the receiver will be when monitoring signals.
However, it is not simply a case of using the narrowest filter at all times. Particular modes require
sufficient amounts of bandwidth in order to operate, otherwise the received signal may not produce
intelligible sound.
The correct receive mode and IF bandwidth must always be selected for optimum reception. If the
bandwidth selection is too narrow, distortion or signal break-up may occur. If the bandwidth selection is
too wide, adjacent interference may be encountered.
For this reason, a selection of commonly used IF filter bandwidths are pre-programmed.
Typical examples of receive mode and IF bandwidth are:
300 kHz -- VHF FM broadcast
200 kHz -- VHF FM broadcast
100 kHz or 30 kHz – Wireless microphone, etc. (example: 30 KHz for satellite FAX)
15 kHz – PMR, amateur band, etc. FM 6 KHz may also be used
6 kHz – VHF/UHF airband, short wave broadcast, medium & long wave, PMR, etc.
3 kHz – Short wave amateur band SSB, short wave utility such as oceanic airband etc.
1 kHz, 500 Hz, 200 Hz – Morse code used by radio amateurs and some marine traffic on SW.
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