Parts List

VHF Enhanced Transmitter Instruction Manual VT-3 132 - 174 MHz 2-3
2.2 Frequency Sel ection
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2.2.1 Synthesizer Transmitter
Eight backplane connections are used to communicate with the synthesizer unit. Pins D28, D30,
and D32 are used (in house) to program the synthesizer. Channel select lines (pins D20, D22,
D24, and D26) are used once the synthesizer is programmed to select one of 16 channels. If the
channel select lines are all low (channel 0) the frequency for the synthesizer is read from switches
FSW1 (most significant), FSW2, FSW3, and FSW4 (least significant). Refer to the VT-3/150
Channel Designation Table Manual for the simplified channel number and frequency information.
For all VT-3/140 models (132-150 MHz) with:
• 5 kHz channel increments (BCD settings from 0000 to 4999):
CHNL#=
Tx
frequency
− 128 MHz
5 kHz






or
Tx
frequency
= CHNL#× 5 kHz [ ] +128 MHz
• 6.25 kHz channel increments (BCD settings from 5000 to 9999):
CHNL#=
Tx
frequency
− 128 MHz
6.25 kHz






+ 5000
or
Tx
frequency
= CHNL#-5000 ( ) × 6.25 kHz
[ ]
+ 128 MHz
For all VT-3/160 models (150-174 MHz) with:
• 5 kHz channel increments (BCD settings from 0000 to 4999):
CHNL#=
Tx
frequency
− 150 MHz
5 kHz






or
Tx
frequency
= CHNL#× 5 kHz [ ] +150 MHz
• 6.25 kHz channel increments (BCD settings from 5000 to 9999):
CHNL#=
Tx
frequency
− 150 MHz
6.25 kHz






+ 5000
or
Tx
frequency
= CHNL#-5000 ( ) × 6.25kHz
[ ]
+ 150 MHz