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You may toggle between the Fast Filter mode and normal mode by continuing to press
the BW button.
D. Exceptions: The receiver's Notch function is not available in the Fast Filter mode
and is automatically deactivated. Also, in ISB mode, IF bandwidth is fixed at 3.2 kHz.
Minimum bandwidth for FM mode is 600 Hz, and 4 kHz for SAM mode. Notch only
works for CW, CW1, LSB, and USB.
4-17 BFO (Beat Frequency Oscillator) button: In the CW detection mode, the
receiver's BFO (Beat Frequency Oscillator) may be adjusted to select sideband (CWU or
CWL) and offset frequency. To enter the BFO Edit function, place the receiver in CW
mode and press the BFO button. The button will illuminate and the Edit Knob will be
assigned to function as the BFO frequency offset control. Offset frequency is displayed
continuously in Hz in the BFO area of the display window:
A. Set BFO Offset via the Edit Knob: Rotate the Edit Knob to select both the desired
Sideband and Offset frequency. Offset may be adjusted continuously from -8 kHz to +8
kHz, a frequency span which takes in both upper and lower sidebands:
1. To select LSB-CW: A positive Offset number (+) places the receiver in CW-
LSB mode.
2. To select USB-CW: A negative Offset number (-) places the receiver in CW-
USB mode.
For CW reception, the offset frequency is normally adjusted to correspond with the
operator's preferred CW listening pitch (400 Hz for example). For digital signal
reception, offset is normally set to the median frequency between the highest and lowest
AF tones required by the modem. When the PBT function is disengaged, BFO offset
frequency relates to the center of the receiver's selected bandpass filter (BW).
Activating another edit parameter switch will disengage the Edit Knob from the offset
function and exit the BFO Edit mode. The displayed offset remains selected until a new
choice is made.
B. Set BFO Offset via the Keypad: Enter the desired Offset frequency (in Hz) via the
keypad followed by the desired sign (+ or -). Your keypad entry will appear in the main
display window. Next, press the BFO button to complete the edit operation. Your
selection will then transfer to the Auxiliary Parameter display, become activated, and the
main display will automatically restore to the receiver's operating frequency.
4-7
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