DE
DANIELS
ELECTRONICS
2-2
VT-3A130VHF AM Transmitter Instruction Manual
2.2
Frequency Selection
2 . 2 . 1
BCD Switch Option.
For operation in this mode, the external channel select must be set to channel 01. Transmitter
channel selection is achieved by setting a decimal number on four BCD frequency select switches,
FSW1 through FSW4. The switch settings are scanned by the synthesizer module when the
transmitter is first powered up, and the desired frequency is generated. Refer to the following
equations or the channel designation tables for simplified channel number and frequency
information.
For VT-3A130 model 118-138 MHz:
• 8.333 kHz channel increments (BCD settings from 0000 to 2400):
CHNL# =
Tx
118 MHz
8.333 kHz
frequency
−
or
Tx
= CHNL# .333 kHz
118 MHz
frequency
×
[
]
+
8
2 . 2 . 2
Frequency Select Handle Option.
For operation in this mode, the external channel select must be set to channel 16. Transmitter
channel selection is achieved by pushing the buttons
Ø
(frequency increase)
Œ
and (frequency
decrease) on the Frequency Select Handle. The Frequency Select Handle is located on the Front
Panel. The user interface consists of an 8 digit display and 3 pushbuttons. On power up or key
press, the synthesizer is interrogated for the current channel number and channel frequencies. This
information is used to generate the display, and update the synthesizer. The module communicates
with the synthesizer using a standard 2 wire serial interface (9600 Baud, 8 bits, no parity, 1 stop
bit). The command protocols are simple ASCII, both to and from the synthesizer.
The frequency value and the channel are displayed on the Front Panel for several seconds only, in
order to conserve the power. Another dedicated line allows the handle to temporarily wake up the
synthesizer if it has been powered down. (This is currently only used on the transmitters)
For detailed information about changing frequency, see the "Frequency Select Handle Instruction
Manual".
